Disadvantage of Partition?

Hi ALL
wHAT is tha disadnantage of Partition?

I'm assuming you're asking about DB (physical)partitions rather than logical partitioning of an InfoCube.
For InfoCubes, each Request is loaded to a new partition of the F fact table. You don't control that - it's automatic. Some partition issues are unique to the DB in use. Generally, you would be compressing an InfoCube regularly so you would not normally ever have so many partitions on the F fact table that it should ever become an issue. If you don't compress your cubes, having several hundred partitions in the F fact table will begin to effect query performance, and would certainly effect any index rebuild time if you are dropping and rebuilding indices on a cube as part of your load process.
As for partitioning the E fact table, that is optional. It can only be done if the InfoCube is empty. Currently, you can only partition a cube on 0FISCPER or 0CALMONTH, so it is difficult to ever see a problem with having too many partitions of the E fact table. Even 10 years of data is only at most, about 120 partition. Partition Pruning is the a process the DB uses when it is going to run a query on a partitioned cube. Let's say you have a cube that has 5 years of data 2001 - 2005. If you created monthly partitions on 0CALMONTH, you would have 62 partitions, 12 per year, plus 2 that the BW generates, one for any data that might have come before 2001 and a partition for any data coming after 2005. Now if you run a query that selects data from 001/2005 - 12/2005, the DB prunes (excludes) all the partitions outside of this range, from consideration - so now it only needs to consider 12 partitions of data for the query instead of all 5 years. Now if your queries usually select on just 0CALYEAR,or 0FISCPER, or 0FISCYEAR, then the DB must look at all the partitions. Queries MUST restrict on the partitioning characteristic for the DB to take advantage of pruing to speed to the query.
Now you can partition the E fact table, but if your queries don't restrict on the partitioning characteristic (fiscper or calmonth) you won; see any query benefit. Partitions can provide some data administration benefit if you perform deletions or archiving based on the partitioing chracteristic - allowing the BW to perfrom a quick Drop Partition rather than having to run a resource intensive Delete query.
If the cube is very small, it probably isn't worth partitioning, but determining he size to consider partitioning might depend on your quereis and how often they'll run.
Partitioning a large ODS would have the same type of benefits. You need to have your DBA partition an ODS since it can not be doen from the Admin Wkbench. An ODS can be partitioned on oher chars, e.g.Business Area so you have more flexibility.

Similar Messages

What are the advantages / disadvantages of partitioning?

I was wondering if there were any advantages to partitioning the hard drive. Seems this choice needs to be made when you first setup your Mac, and as mine is on its way the time to ask is now.
Has anyone partitioned their drive? Why? Why not?

James,
The greatest advantage to having a secondary volume is that this will allow you to store much of your data on that secondary. For example, my iPhoto and iTunes libraries (by far the largest disk-eating portions of my data) are both stored on my secondary volume.
This helps me manage the size of my HOME folder, and thus makes the maintainance of a comprehensive backup very much easier for me. In the event that I must format my startup disk and reinstall OS X, I will have less to worry about. You see, a secondary volume is much less likely to suffer from a crippling disk error than is a boot volume, and one volume can be formatted independently, without affecting the other.
In addition to providing the constant protection for certain portions of my data, as outlined above, the secondary volume can be used to make or keep a backup of the rest of my HOME folder. I normally use an external drive to handle this, but that secondary volume can be used in a pinch. It's just one extra layer of protection.
The only limitation to this scheme is that it doesn't provide any protection at all from a hardware failure of the drive, itself; it only helps reduce the pain of a file system catalogue failure on the boot volume.
Scott

How to choose the partition in oracle tables?

Dear all,
i m in need to create the partitions on prod.db tables since i m not aware of creating partitions?i just go through some theroy concepts and understood the range and list partitions (i.e)Range is normally used for values less than like jan,feb,march or values less than 50,000 values less than 1,00,000 like that each partition is having separate tablespaces to increase the performance. and for list is used to denoting the directions like west,east,north,south like that.
Now what i want to know is ?
1.)when will i can go ahead with partitions?
2.)before creating partitions is it advise to create index or not needed?
3.)if i started to create partition what is the leading column have to create partition and which partition has to choose?
pls let me know and pardon me if i did any mistakes.
thanks in advance..

I had to research on same topic. One of my teammates suggested few points that might help you also.
Advantages of partitioning:
1) Partitioning enables data management operations such data loads, index creation and rebuilding, and backup/recovery at the partition level, rather than on the entire table. This results in significantly reduced times for these operations.
2) Partitioning improves query performance. In some cases, the results of a query can be achieved by accessing a subset of partitions, rather than the entire table. Parallel queries/DML and Partition-wise Joins are also got benefited much.
3) Partitioning increases the availability of mission-critical databases if critical tables and indexes are divided into partitions to reduce the maintenance windows, recovery times, and impact of failures. (Each partition can have separate physical attributes such as pctfree, pctused, and tablespaces.)
Partitioning can be implemented without requiring any modifications to your applications. For example, you could convert a nonpartitioned table to a partitioned table without needing to modify any of the SELECT statements or DML statements which access that table. You do not need to rewrite your application code to take advantage of partitioning.
Disadvantages of partitioning:-
1) Advantages of partition nullified when you use bind variables.
Additional administration tasks to manage partitions viz. If situation arises for rebuilding of index then rebuilding should to be done for each individual partition.
2) Need more space to implement partitioning objects.
3) More time for some tasks, such as create non-partitioning indexes, collection of “global" statistics (dbms_stat’s granularity parameter to be set to GLOBAL. if sub partition are used then we have to set it to ALL).
4) Partition would implies a modification (of explain plan) for ALL the queries against the partitioned tables. So, if some queries use the choosing partition key and may greatly improve, some other queries not use the partition key and are dramatically bad impact by the partitioning.
5) To get the full advantage of partitioning (partition pruning, partition-wise joins, and so on), you must use the Cost Based Optimizer (CBO). If you use the RBO, and a table in the query is partitioned, Oracle kicks in the CBO while optimizing it. But because the statistics are not present, the CBO makes up the statistics, and this could lead to severely expensive optimization plans and extremely poor performance.
Message was edited by:
Abou

Why not partition every table

Hi ,
In our project we propse to partition all the tables(Even though they are small which are in MBs) in order to use exchange partiion feature.
But Our DBAs are saying that Maintainance will be a problem if we create partitions for each and every table.We said ,single tablespace is fine for all the partitions as We thought maintaining different tablespaces is a problem.
But Still DBAs are not approving it.
I just want to know what are the disadvantages of partitioning.Why DBAs in general are against the idea of creating partitions.If we use same tablespace for all partitions is there any down side for creating partitions for every table ?
Is there are disadvantage ?
Thanks
Pramod Garre

Pramod Garre wrote:
We are planning to use range partitioning (on quarters).
There is requirement to delete one quarter data from the table and then refresh with new data as and when user update some recored from frontend.this should happen in real time.Sounds like you are having the app trigger partition management ... which doesn't strike me as a good idea.
It also sounds like you really only have justification for partitioning on a few tables. Far from the "every" table you asked about. And even at that it sounds like your concept of the usage of those partitions may be flawed.
Why not work with your DBAs instead of looking to strangers for justification to fight them. Sounds to me like they are doing exactly what they were hired to do.
We thought instead of delete and insert , if we use excahnge partitions , this will be real quick as exchange partition just update the dictionary.
On these lines,do you think will there be any disadvantages of using partitioning ?
Note : Delete and Insert is working OK (2 Mins ) as compared to exchange partition ( 20 ms ).
And Yes,Every table has PK.
Thanks
Pramod Garre

Best way to cofigure/format/partition a new 500GB external HD.

I have a new 500GB Seagate Firewire/USB HD. I want to do this right the first time so I'm asking for advice. I'm sure there are different philosophies on "what's best" and I'ld like to hear some suggestions and different options and why or why not, to do or not to do...advantages and disadvantages on:
Partitions, formats, configurations, RAID, striped RAID, mirrored RAID, concatenated RAID, etc..

The fastest your drive will be able transmit or recieve will be about 40 MBytes a second (or about 320 Mbits/sec) assuming you are running it USB 2.0
Your seagate has a top speed of around 68-72 MB/ sec at the beginning of the drive and slows to half that for the last third.
If this was an internal drive I would recomend partitioning it with a 1:2 ratio (166:333) and put your OS, applications and all your current files on the first partition and using the second for storage. That way all the often accessed files are at the front/outer/faster part of the drive. This ensures that even after multiple updates, defrags, and reinstallations of the OS those files remain on the "zippy" part of the drive.
BUT
Because this is an external drive the USB speed limitation negates MOST of the speed advantage gained by partitioning. If you want to make a seldom used OS-boot partition put it at the end of the drive (slowest part).
Having the option to boot several different OSX versions is in the realm of Apple fetishism, and OS9 is for Luddites. You have OS 10.4.8 now and we can only hope that each new OS has been better than the last. The only time an older OS can be an advantage is sometimes 3rd party hardware becomes "unsupported" by OS updates.
For better data security go journaled.
If you really want to get the most out of your drives take the new seagate out of the external enclosure and install it as your internal drive. Hard drives are the slowest piece of hardware in your computer. (and the slowest to get faster - CPU speed has at least quadrupled in the last 4 years, hard drives have about doubled their speed) The seagate is a smoking fast drive and you would get an immediate and noticable overall performance improvment over your stock 80Gig drive due to faster access/reads/writes and faster virtual memory. Applications will load faster and boot time will be practically cut in half.
Given the choice of two drives you should always use the newer of the two as the opperating drive and the older as the backup. (just like with car tires newer=less chance of needing a backup)
I realize taking apart your snowcone may be daunting but switching your internal drive will really make a big performance difference, and put your newer, more reliable drive where it can do the most good.
Just some thoughts.

Recommendations on partitioning a large external hard drive.

Hello
Well, I'm stepping up and purchasing a new Western Digital MyBook 500 GB external hard drive.
What's the current thinking on partitioning something like this? I thought at least making one or two 50 GB partitions in case I want to load parallels and run windows from one section. Otherwise, will be using this largely for backups and media files (music, films). Any thoughts on advantages/disadvantages of partitioning would be great.
Thanks in advance!
MBP 2.16 2GB Mac OS X (10.4.9)

Hi,
I do have the same drive (actually 2, one for each) and had them partitioned in a way to have one partition with 50GB as a sort of 'disaster boot' with a OSX system on it (made with SuperDuper) and the rest for backup purpose.
As for Parallels, the main app must be on your boot-up system, whereas the VM could very well be put on another, even external, drive.
So far no problems.
Regards
Stefan

Help needed in tuning this query

This is the SQL i would like to tune for performace...
The table structure is given below.
The table has about 2 million rows.
From the second day onwards only around 10% of records will be between Load_Start_Time and Load_End_Time. Among these around 50% will have THAMES_URN_WITH_ROLE_SUFFIX as 'TP%'. At present there are unique and primary key indexes on THAMES_URN_WITH_ROLE_SUFFIX .
I'm sure that we need a b-tree index on STG_UPDATE_DATE_TIME as it is the column with good selectivity.
I'm primarily concerned about the substr, instr and reverese on THAMES_URN_WITH_ROLE_SUFFIX.
Also pls. let me know if the order of predicates is right.
Thanks in advance.
SELECT TPD_STG_TL_SF_LEGAL_OWNER.THAMES_URN, TPD_STG_TL_SF_LEGAL_OWNER.UPDATE_SOURCE, TPD_STG_TL_SF_LEGAL_OWNER.SOURCE_EXTRACT_DATE_TIME, TPD_STG_TL_SF_LEGAL_OWNER.LEGAL_OWNERSHIP_ISSUE_IND, TPD_STG_TL_SF_LEGAL_OWNER.CONTACTABLE_INDICATOR, TPD_STG_TL_SF_LEGAL_OWNER.ADMIN_CONTROL_INDICATOR, TPD_STG_TL_SF_LEGAL_OWNER.BANKRUPTCY_INDICATOR, TPD_STG_TL_SF_LEGAL_OWNER.ASSIGNED_INDICATOR, TPD_STG_TL_SF_LEGAL_OWNER.IN_TRUST_INDICATOR, TPD_STG_TL_SF_LEGAL_OWNER.DIVORCE_CASE_INDICATOR, TPD_STG_TL_SF_LEGAL_OWNER.POA_COP_INDICATOR, TPD_STG_TL_SF_LEGAL_OWNER.CLEANSING_STATUS, TPD_STG_TL_SF_LEGAL_OWNER.CATEGORY
FROM
TPD_STG_TL_SF_LEGAL_OWNER
WHERE
((TPD_STG_TL_SF_LEGAL_OWNER.STG_UPDATE_DATE_TIME > '$$Load_Start_Time'
AND
TPD_STG_TL_SF_LEGAL_OWNER.STG_UPDATE_DATE_TIME <= '$$Load_End_Time')
OR
(TPD_STG_TL_SF_LEGAL_OWNER.TPDB_PROCESSED_IDENTIFIER != 'Y') )
AND
SUBSTR(TPD_STG_TL_SF_LEGAL_OWNER.THAMES_URN_WITH_ROLE_SUFFIX,1,2)='TP'
AND
SUBSTR(REVERSE( TPD_STG_TL_SF_LEGAL_OWNER.THAMES_URN_WITH_ROLE_SUFFIX),INSTR(REVERSE( TPD_STG_TL_SF_LEGAL_OWNER.THAMES_URN_WITH_ROLE_SUFFIX),'-',1)-1,1)!='S'
========================================
CREATE TABLE TPD_STG_TL_SF_LEGAL_OWNER
THAMES_URN VARCHAR2(35 BYTE) NOT NULL,
UPDATE_SOURCE VARCHAR2(3 BYTE),
SOURCE_EXTRACT_DATE_TIME DATE,
LEGAL_OWNERSHIP_ISSUE_IND CHAR(1 BYTE),
CONTACTABLE_INDICATOR CHAR(1 BYTE),
ADMIN_CONTROL_INDICATOR CHAR(1 BYTE),
BANKRUPTCY_INDICATOR CHAR(1 BYTE),
ASSIGNED_INDICATOR CHAR(1 BYTE),
IN_TRUST_INDICATOR CHAR(1 BYTE),
DIVORCE_CASE_INDICATOR CHAR(1 BYTE),
POA_COP_INDICATOR CHAR(1 BYTE),
THAMES_URN_WITH_ROLE_SUFFIX VARCHAR2(39 BYTE),
THAMES_LEGAL_OWNERSHIP_IND CHAR(1 BYTE),
PRODUCT_HOLDING_ROLE_TYPE VARCHAR2(21 BYTE),
OWNERSHIP_SPLIT_PERCENTAGE NUMBER(3),
SOURCE_SYSTEM VARCHAR2(3 BYTE),
TITLE VARCHAR2(50 BYTE),
FIRST_NAME VARCHAR2(50 BYTE),
MIDDLE_INITIAL VARCHAR2(50 BYTE),
SURNAME VARCHAR2(50 BYTE),
GENDER CHAR(1 BYTE),
BIRTH_DATE DATE,
DEATH_INDICATOR CHAR(1 BYTE),
DEATH_RECORD_DATE DATE,
NATIONAL_INSURANCE_NUMBER VARCHAR2(9 BYTE),
GONE_AWAY_INDICATOR CHAR(1 BYTE),
ADDRESS_LINE_1 VARCHAR2(50 BYTE),
ADDRESS_LINE_2 VARCHAR2(50 BYTE),
ADDRESS_LINE_3 VARCHAR2(50 BYTE),
ADDRESS_LINE_4 VARCHAR2(50 BYTE),
ADDRESS_LINE_5 VARCHAR2(50 BYTE),
POST_CODE VARCHAR2(12 BYTE),
COUNTRY VARCHAR2(50 BYTE),
OVERSEAS_ADDRESS_INDICATOR CHAR(1 BYTE),
ORGANISATION_NAME VARCHAR2(50 BYTE),
TPDB_PROCESSED_IDENTIFIER CHAR(2 BYTE),
CLEANSING_STATUS VARCHAR2(30 BYTE),
CATEGORY VARCHAR2(50 BYTE),
SCHEME_NAME VARCHAR2(50 BYTE),
STG_CREATE_DATE_TIME DATE,
STG_UPDATE_DATE_TIME DATE,
LAST_UPDATED_DATE_TIME DATE
TABLESPACE TPDBS01A_DATA
PCTUSED 0
PCTFREE 10
INITRANS 1
MAXTRANS 255
STORAGE (
INITIAL 128K
NEXT 128K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
LOGGING
NOCOMPRESS
NOCACHE
NOPARALLEL
MONITORING;
CREATE UNIQUE INDEX TPD_STG_TL_SF_LEGAL_OWNER_PK ON TPD_STG_TL_SF_LEGAL_OWNER
(THAMES_URN_WITH_ROLE_SUFFIX)
LOGGING
TABLESPACE TPDBS01A_DATA
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 128K
NEXT 128K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
NOPARALLEL;
ALTER TABLE TPD_STG_TL_SF_LEGAL_OWNER ADD (
CONSTRAINT TPD_STG_TL_SF_LEGAL_OWNER_PK
PRIMARY KEY
(THAMES_URN_WITH_ROLE_SUFFIX)
USING INDEX
TABLESPACE TPDBS01A_DATA
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 128K
NEXT 128K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
));

> If indexes don't help, is the only way to gain REAL
performance gain on this type of query is to
partition the table
If a Full Table Scan on a table takes "too long" (and
this is purely subjective - "too long" is different
for every problem) and indexes can't help, and we
need <100% of the rows, and if partitioning will give
us the performance we desire, is it OK do it ? Also
would STG_UPDATE_DATE_TIME be the best column to do a
index partion ?
For this type of query, partitioning on STG_UPDATE_DATE_TIME would be good.
However, partitioning is not done just for one query. It has to fit in your total design. For example, if you are also doing queries with a predicate like <column with a local unique index but not the partition key> = <constant>, it would have to visit all partitions instead of just one, and those queries would take much longer to execute. You can make the index global, but there all kind of maintenance issues with that. In short: be careful about partitioning and think it through first.
> But is it a good option to partition tables with
total no. of rows between 2 million and 5 million ? I
thought partitioning is better done for tables > 20
million.
Please throw some light on that.
Generally, partitioning is done on bigger tables, yes. But it is not about some specific number of rows. You partition a table when all forecasted use of the table is known, so you can make a good judgement which usages will benefit, which ones won't be affected and which ones are likely to suffer. When the benefits outweigh the disadvantages, you partition...
Above I had an example about queries that are going to suffer. Partitioning is beneficial for example when once in some period you'd have to delete A LOT of old rows. Or when you have some data warehousing queries that need like 10% of only the most recent data in a huge table.
The decision is yours.
Regards,
Rob.

How do I copy a TM backup to an external HDD with an existing TM backup (for another machine)?

Hi,
My question relates to the use of Time Machine for two different Macs ... I have two Macs: a MacBook Pro (ML) and an iMac (SL). I use Time Machine for both.
Unfortunately, the external HDD (A) drive I use for the backup of my MacBook Pro is on the way out. I am now in a situation where I need to copy this Time Machine backup to another external HDD (B) which I use for the backup of my iMac.
I have decided that I would like to use external HDD B for all future backups of both machines from now on. It is a 2Tb LaCie drive with one partition. Therefore, I would like to copy the Time Machine backup data from external HDD A to external HDD B. Since both TM files/directories have identical names, I am looking for some advice of how to do this without 'deactivating' any of the backups or corrupting them, or screwing with permissions.
In case this is known to be problemmatic, would it be 'better practice' to partition the external 2Tb HDD drive into two partitions, then just use one partition for each backup? Is there an advantage/disadvantage to partitioning the drive? Will this approach make it 'less confusing for Time Machine' and reduce potential problems?
Any advice would be great!
Thanks,
Mark.

Don't bother trying to copy a TM backup file. Just connect the other good drive to your MBP and create a new full TM backup on that drive. I do suggest you create a separate partition on that good drive for each Mac you will be backing up to it.

How many copies of 10.2.8 can I have on one HDD? To partition or not to ...

Hi,
I hope that this makes sense to those who read it. If, it doesn't then, please - someone say so. In case some of you recognize my monicker it has been a good while since I visited and asked for help.
Kappy, I didn't understand everything - had some health issues thus, I couldn't followup?
I have finally installed my Seagate internal, thus my return visit.
I have just installed a Seagate Barracuda 7200, 120 GB HDD. I've made it my master drive. I've partitioned it into four parts. 1) for OS 10.2, 2) for 10.3, 3) for 10.4 and 4) for OS 9. I have not yet put it to use. I made my original Deskstar 40GB the slave, it has three partitions. 1) for 10.2, 2) for OS 9 and legacy 3rd party apps and 3) for photos and videos. I also have an Maxtor One-Touch II External 300 GB FW for backup. Long story - it has 4 partitions, 1) 10.2, 2) 10.3 and .4, 3) for video and photo storage and 4) for OS 9.
I have several questions.
1) How many copies of OS 10.2.8 can I have on any one drive - is my Seagate and my Deskstar now considered to be one drive?
1b) Can I have OS 10.2.8 (on both? of them)?
1c) Can I have 10.2.8 on that/both of those drives without causing conflicts or any other problems?
2) I've been reading through the discussions to see if I could find an answer to any of these questions. What I did find was several different topics that include references about not partitioning new drives.
2a) What are the advantages to partitioning and what are the potential problems/disadvantages created by partitioning a new HDD?
2b) Isn't it necessary to partition a HDD if I'm going to have 10.2, 10.3(maybe), 10.4 and OS 9 all on the same HDD?
2c) Aren't there going to be conflicts especially because of OS 9 and 10.4 being on the same partition?
I will appreciate all replies, corrections, suggestions and requests for clarifications and/or request for additional info.
Thanks,
J Ivan
P.S. I'm now going to bed and I won't be back on-line until late this afternoon.
PowerMac G4 Dual 500 Gigabit Ethernet, ATI Rage 6 w/16 MB, Rage 128 w/32MB, iMic USB Mac OS X (10.2.x) HP's Laserjet & Scanjet, APC Back-UPS LS 500 USB
PowerMac G4 DP Gigabit Ethernet Mac OS X (10.2.x)

1) How many copies of OS 10.2.8 can I have on any one drive - is my Seagate and my Deskstar now considered to be one drive?
1b) Can I have OS 10.2.8 (on both? of them)?
1c) Can I have 10.2.8 on that/both of those drives without causing conflicts or any other problems?
You cannot have more than one copy of OS X on a single volume (partition), but you can install any number of versions of OS X on separate volumes (partitions.)
2) I've been reading through the discussions to see if I could find an answer to any of these questions. What I did find was several different topics that include references about not partitioning new drives.
2a) What are the advantages to partitioning and what are the potential problems/disadvantages created by partitioning a new HDD?
There are no inherent advantages to partitioning in general except that it may provide a convenient means for organization. However, if you desire to install multiple operating systems, partitioning is necessary to keep each OS separate and to enable you to use OPTION booting. The exception to this is installing OS X and OS 9 on the same volume.
2b) Isn't it necessary to partition a HDD if I'm going to have 10.2, 10.3(maybe), 10.4 and OS 9 all on the same HDD?
Yes. See previous answers.
2c) Aren't there going to be conflicts especially because of OS 9 and 10.4 being on the same partition?
No. And there would be no problems having OS 9 and 10.4 on the same volume. If they are on the same volume you simple cannot use OPTION booting to switch between them.

How to create multi volume partition

Hi
I'm trying to figure out how I can create one single partition accross multiple disks so that I basically can extend the partition at the moment I'm running out of diskspace. The disks that I use are western digital mybook daisychained via firewire 800.
I tried to find option in diskutil but couldn't find it, possible that this might be doable on the command line but I'm too unfamiliar with it.
Any suggestions are highly appreciated.
Thanks in advance,
Frans van Wessel

Matt Clifton wrote:
The only way to do what you want with Mac Extended format is to use RAID to stripe a volume across multiple disks. However, it is not dynamic in that you cannot add space later in the way you describe.
I feel I must add that in addition to missing "dynamics" and a few other disadvantages, RAID 0 is highly dangerous due to zero fault tolerance. If only one of the partitions/drives goes bad, none of the data on all of the partitions can be accessed anymore!
fvwessel, you better locate large portions of your data, such as videos, music, photos, onto separate, individual and independent drives. It'll make it safer, and typically all apps are supporting it.

Time Machine Backup Generations on several partitions

I used an iMac for almost a year. At the beginning I established Time Machine Backup to a large WD FireWire drive and then I let it on its own, satisfied to have a safe backup system. After that year, I bought a new iMac and selected the option to restore my data from the said TM Backup. So far, this worked fine, except for certain applications, which showed that data were missing (the worst was iPhoto with many photos disappeared).
Since this experience (and a similar experience I made earlier), I don't trust TM fully. TM for me is still a convenient tool which helps to revert to certain situations after inadvertent deletions or changes.
What I'm planning to do now, is to use a large (2TB) drive and to partition it into 6 partitions (A, B, C, D, E, F, all of the same size, each of them will be large enough for a TM Backup of my data for many months). Every 2 to 3 month I intend to start a new TM Backup, to a new partition in each case. After partition F has been used, partition A will be erased an then used again for backup (and so on), or I might even buy a new backup drive. This is to avoid Time Machine Backups to the same destination for a very long time period.
Now my question: Let's assume the current TM backup is made to partition D, when I find out, that I need a file from the backup in partion B a few months ago. Is it possible, to access an old TM backup after new TM backups have been started?
Thanks for your answer.

First of all: Thanks for your response!
Pondini wrote:
... feel free to tell Apple at: http://www.apple.com/feedback/timemachine.html
I'm going to do that.
... But it should "catch up" with the changes on a subsequent backup when iPhoto is not open.
It certainly should, but I doubt it does. Before I put the old iMac out of operation, I stopped all applications (including iPhoto) and then I forced a TM backup - with the result that iPhoto data were missing.
... but a much better solution may be making separate, independent backups to a separate HD via a separate app. See #27 in Time Machine - Frequently Asked Questions (or use the link in *User Tips* at the top of this forum), for some suggestions.
Of course, I additionally make separate, independent backups from time to time. For that I create a Disk Image by means of the Disk Utility, booted from the Install DVD. This seems to me the only way to be sure, that no files are open. The disadvantage of this method however ist, that it might not work to be used for backup to another Mac (different drivers), unless the other Mac it is identical.
But I believe, that the longer TM runs to a certain backup set, the more vulnerable it becomes. That's why I want to keep the backup period to the same backup set relatively short (2 to 3 months). Something else: The longer TM runs to the same backup set, the slower it becomes (that's something I have definitely observed).
Yes. Use the +*Browse . . .+* option, per #17 in the FAQ.
This answers my question. I appreciate it.

How much room should be partitioned for Windows XP?

Alright, I have a different install disc for XP with SP3 which should work. Since I'll only be using XP for a couple of things (mainly small programs, but also for office and such), how much room should I leave for XP on my 320 gig HD so that both OSs have some breathing room (most of my other stuff like music and pictures are on the Leopard side of things)?

But I hear that it has better compatibility to run FAT32 than NTFS. Does it really matter too much?
While OSX is able to read and write to FAT32 partition, it can only read from NTFS partitions.
With the help of apps like NTFS-3G http://www.ntfs-3g.org/ and/or NTFS for Mac http://www.paragon-software.com/home/ntfs-mac/ OSX can also write to NTFS partitions.
To me personally this is no problem, since I want OSX and Windows to seperated (I even have Windows on a harddisk of its own in my Mac Pro) and for file exchange between OSX and Windows I use an external FAT32 HD.
But the advantage of the newer, better and more robust NTFS file system outweighs these 'disadvantages'.
And FAT32 has a file-size limitation for single-files of 4GB.
Also, not to be pessimistic, but what if something goes wrong with the partition or install? Can I restart my Mac and would it be unaffected? This disc should work, but I want to know just in case...
Before 'fumbling' with any kind of partitioning on a harddisk I always make a backup of my important files, or better said I use SuperDuper to make a bootable clone of my OSX.
While the chances that something goes wrong are quite slim (I have made the partitioning with the BootCamp Assistant for about 10 times now), the possibility is always there.
Stefan

Boot Camp Partition Size/External HDD recommendation

After updating software, hardware, downloading Boot Camp Asst, and installing Windows XP Pro (have not yet downloaded Mac drivers or software, nor have I submitted registration of my WinXP Pro software, still have 29 days), I realized that I set the partition size too small and need to resize it. I read in other postings that I can copy the Windows partition to an external HDD from the Mac OSX side, then run Boot Camp again, delete the "too small" Windows partition, then run Boot Camp again and reset the partition size larger. Does anyone have detailed instructions to do this?
Also, can anyone suggest an external HDD for this purpose? I need to be able to share files between a PC and my 17" MBP running OS X 10.4.6. Specifically, I need to share (for editing purposes) audio files created with PC-based software with the Windows side of my MBP. The PC has XP Pro and MacDrive6 for Windows installed. I read the "Sharing a FireWire drive between Mac and PC" document on "The X Lab" website and, based on this, am leaning toward getting a FW (not USB) HDD and formatting it in Mac OS Extended format (not sure how to do this but cross that bridge when I get there). Does this sound reasonable? When I run Boot Camp again and have to choose between NTSF and FAT32 should I choose NTSF? Will I also need "SharePoints" or other software to share the Mac's FW drive with the PC?
I may have the option to share and backup files over the workplace network (if I take the time to set it up). Does anyone know if there advantages/disadvantages to this option?
Thanks for answers to these questions. Any help would be very much appreciated. Best!

Frank,
You might want to check the Boot Camp discussions:
http://discussions.apple.com/forum.jspa?forumID=1165
In case no one in this part of the board knows.

What is a bootable backup and do i need one? what are partitions good for?

hello,
please excuse my ignorance...
i just got a new lacie external firewire hard drive and it has some software which i was wandering if i have any use for... - SilverKeeper and LaCie Backup Software. i'm not sure if they can give me anything that time machine doesn't do better... SilverKeeper gives the option of cloning a bootable backup. i'm not exactly sure what's the advantage of this and in what case i may need it.
when i got my last computer i was able to transfer everything from the old computer, including applications, to the new one without having to find all the serial numbers and reinstall them. i thought that time machine will be able to do the same thing if i lose all the data on my computer. is that not so? is that what a bootable clone is for? or what is it for?...
my other question is what are the advantages of making partitions in my new drive (i understand i have to if i want a bootable backup, but is there any reason to partition otherwise?
thanks!
dannah

SilverKeeper gives the option of cloning a bootable backup. i'm not exactly sure what's the advantage of this and in what case i may need it.
A bootable backup is an exact copy of your hard drive's contents on another drive, that can be used for booting up the machine. The advantage of a bootable backup is that, in the event something bad happens to your internal drive, you can very quickly get up and running with the backup drive, and can copy that back to a replaced/fixed internal drive very quickly. Time Machine backups are not bootable.
The disadvantage of a clone of any kind, bootable or not, is that there's only one version of any particular file stored. So if a file gets damaged and then backed up, you're pretty well screwed with the clone, while Time Machine stores many versions of the file, so you just "roll back" to the last working copy.
when i got my last computer i was able to transfer everything from the old computer, including applications, to the new one without having to find all the serial numbers and reinstall them.
Bad idea... while this will work for most apps, different machines have different architectures, so some apps may not be installed correctly for the new machine, plus you may not have properly copied some components. You should have reinstalled them.
i thought that time machine will be able to do the same thing if i lose all the data on my computer. is that not so?
If you have Time Machine back up the entire hard drive, without excluding anything, then Time Machine should be able to restore your drive to exactly the way it was at any particular moment in time at which it made a backup, including apps, system files, preferences, etc.
my other question is what are the advantages of making partitions in my new drive (i understand i have to if i want a bootable backup, but is there any reason to partition otherwise?
You do not have to partition to make a bootable backup. However, you'll be using the entire drive... trying to store additional files on the same drive as a bootable clone is confusing at best. Using a partition allows you to create multiple "virtual" drives... say, one for a bootable backup, one for a Time Machine backup, one for movie files, etc. Of course, this is only advisable if the drive is much larger than the one you're backing up, and note that if you store original files on a partition (like a bunch of movie files), you need a backup of those somewhere else.
Time Machine will want it's own full drive or partition to play with, which should be larger than the drive being backed up, and will eventually fill it. A bootable clone probably also should go onto its own partition, but you wouldn't need to make this partition larger than the drive being cloned. Other than that, don't worry about partitioning unless you have a specific need.

About: making RAID sets - partition independant?

(the querry made simple: look last 2 lines)
When making a RAID set, whatever the type it is, will it rely on the partitions or on the disk itself?
In the Disk Utility help it keeps mentioning "disk", and when I was about to create a set, it also asked me about "disk".
I have set up 2 partitions for the purpose of testing RAID for me, being about the same size on a big backup drive.
The drive itself also has a bit of free space filled with original files.
So I wanted to mirror, say, RAID test 1 and RAID test 2, both of them being on the same disk.
Will it work?
Or will it wipe my disk?

A RAID may be constructed using individual partitions on separate drives although using the whole drive would be preferred for speed. You could actually RAID multiple partitions on the same drive, but of course what would be the point.
I've actually used two drives each with three separate partitions and created three separate RAIDs of two partitions each. Not particularly efficient but it does work.
There is really no point to creating a RAID of two partitions on the same drive. And, certainly no point creating a mirrored RAID this way.
Any RAID you create with Disk Utility will erase the drives used (or partitions.)
RAID Basics
For basic definitions and discussion of what a RAID is and the different types of RAIDs see RAIDs. Additional discussions plus advantages and disadvantages of RAIDs and different RAID arrays see:
RAID Tutorial
RAID Array and Server: Hardware and Service Comparison>.
Hardware or Software RAID?
RAID Hardware Vs RAID Software - What is your best option?
RAID is a method of combining multiple disk drives into a single entity in order to improve the overall performance and reliability of your system. The different options for combining the disks are referred to as RAID levels. There are several different levels of RAID available depending on the needs of your system. One of the options available to you is whether you should use a Hardware RAID solution or a Software RAID solution.
RAID Hardware is always a disk controller to which you can cable up the disk drives. RAID Software is a set of kernel modules coupled together with management utilities that implement RAID in Software and require no additional hardware.
Pros and cons
Software RAID is more flexible than Hardware RAID. Software RAID is also considerably less expensive. On the other hand, a Software RAID system requires more CPU cycles and power to run well than a comparable Hardware RAID System. Also, because Software RAID operates on a partition by partition basis where a number of individual disk partitions are grouped together as opposed to Hardware RAID systems which generally group together entire disk drives, Software RAID tends be slightly more complicated to run. This is because it has more available configurations and options. An added benefit to the slightly more expensive Hardware RAID solution is that many Hardware RAID systems incorporate features that are specialized for optimizing the performance of your system.
For more detailed information on the differences between Software RAID and Hardware RAID you may want to read: Hardware RAID vs. Software RAID: Which Implementation is Best for my Application?

Disadvantage of Partition?

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