Allocation of space for 3-Way Mirror

A picture paints a thousand words, so I painted. Far easier than tying myself up in knots of words.
Many thanks.

Hi,
A1: 450GB is correct.
A2: The 2 disks requirement is not static. See the explanation in following article, that why it needs 5 disks for a 3-way mirror:
http://blogs.technet.com/b/tip_of_the_day/archive/2013/08/29/tip-of-the-day-3-way-mirrors.aspx
The reason is that a 3-way mirror uses a quorum. In order to keep running, the mirror space must keep over 50% of the disks functioning. So a 3-way mirror must have at least 5 physical disks to be able to survive the loss of up to 2 physical
disks.
Below is my personal view: With 9 disks act as 3-way mirror, we could lost 6 disks in maximum. As it must keep over 50% of disks in running, we need more than 4.5 disks which is 5, so we need 2 more disks.
Please remember to mark the replies as answers if they help and un-mark them if they provide no help. If you have feedback for TechNet Support, contact [email protected]
Thanks for this, Shaon Shan.
When it comes to a 3-way mirror, is a better way of calculating the total amount of enclosure storage for the desired amount of usable storage, to multiply your desired usable storage by a factor of 5?
So, if using 500GB drives, to have 1TB of usable storage from a 3-way mirrored virtual disk, I would need to have 5TB of total storage, so a complete total of 10 drives?

Similar Messages

Clustered Storage Spaces - 3 disk minimum for 2-way mirror?

Why will a 2 disk, 1 column, 2-way mirrored space work fine outside of a cluster? Yet, when I want to use clustered storage spaces I need a minimum of 3 physical disks for a 2-way mirrored space? Killing me...
I mean if I add 2 additional disks and do a 4 disk, 2 column, 2-way mirrored space it's ok. What would be the purpose of using 3 disks as a minimum?
Thanks,
Scott

Hi,
Could you please give us more detailed explanation to help us understand your question?
“Cluster storage space” did you mean “Cluster Share Volume” for Hyper-V Cluster?
What did you mean “mirrored space”, did you mean software mirrored volume? For a cluster, we recommend you use a shared storage and configure disk fault tolerance with hardware RAID.
Give us more information of your questions for further troubleshooting.
For more information please refer to following MS articles:
Mirrored Volumes
http://technet.microsoft.com/en-us/library/cc938487.aspx
How to Configure a Clustered Storage Space in Windows Server 2012
http://blogs.msdn.com/b/clustering/archive/2012/06/02/10314262.aspx
Understanding Requirements for Failover Clusters
http://technet.microsoft.com/en-us/library/cc771404.aspx
Hope this helps!
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Three-way mirror disk requirement

In Windows 2012 Storage Space, why 3-way mirror requires minimum 5 disks instead of 3? How does 3 way mirror works? I tried to find the tech paper on MS website but either I didn't try hard enough or the info is not there.

Hi,
The reason is that a 3-way mirror uses a quorum. In order to keep running, the mirror space must keep over 50% of the disks functioning. So a 3-way mirror must have at least 5 physical disks to be able to survive the loss of up to 2 physical disks.
For more detailed information, please refer to the links belwo:
Tip Of the Day: 3-way Mirrors
http://blogs.technet.com/b/tip_of_the_day/archive/2013/08/29/tip-of-the-day-3-way-mirrors.aspx
mirror in storage pool
http://social.technet.microsoft.com/Forums/windowsserver/en-US/2e6955b7-b293-4880-8fb3-8b4ce0e02ec9/mirror-in-storage-pool?forum=winserver8gen
You could also refer to the article below to know more about three-way mirror:
Windows Server 2012 SMB 3.0 File Shares: An Overview
http://www.petri.co.il/windows-server-2012-smb-3-file-shares.htm
Please Note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
Regards,
Mandy
We
are trying to better understand customer views on social support experience, so your participation in this
interview project would be greatly appreciated if you have time.
Thanks for helping make community forums a great place.

How to calculate the disk failure level for a 3-way mirror pool?

On another post in this forum, the following information regarding a 3-way mirroring storage pool is given:
Pool requires a quorum of 50% plus drives to be present to survive.
with 3 way mirror - we have a guarantee of surviving 2 disk failure.
Maintaining the above requirements and providing the guarantee -
mandates us to have minimum 5 disks in pool. As if we loose 2, we still
have 3 in the pool (>50%) for pool to maintain it's quorum.
Just to be sure, I would like Microsoft to confirm that the following calculation applies to any number of disks in a 3-way mirroring pool.
If the number of disks in a 3-way mirroring pool is n, INT(n/2) disks can fail without data loss.
Examples:
With 5 disks, INT(5/2)=INT(2.5)=2 disks can fail.
With 6 disks, INT(6/2)=INT(3)=3 disks can fail.
With 9 disks, INT(9/2)=INT(4.5)=4 disks can fail.
Am I right in this assumption?
Thanks for your answer.

Hi,
>>Am I right in this assumption?
Based on my understanding, it’s not this case.
Mirror spaces are designed for increased performance and protect your files from drive failure by keeping more than one copy. Two-way mirror spaces make two copies of your
files and can tolerate one drive failure, while three-way mirror spaces can tolerate two drive failures.
Regarding this point, the following thread can be referred to for better understanding.
Storage Spaces - Disk resiliency
http://social.technet.microsoft.com/Forums/en-US/8f13ecf3-61c8-4505-90da-e8a01023c62d/storage-spaces-disk-resiliency?forum=winserverfiles
In addition, regarding storage spaces, the following article can be referred to for more information.
Storage Spaces Overview
http://social.technet.microsoft.com/wiki/contents/articles/15198.storage-spaces-overview.aspx
Best regards,
Frank Shen

2 Way mirror via Storage Spaces using 2xJBODS

Looking to setup 2xJBODS connected to a cluster File Servers & use 2-WAY mirror for the pool. Its clear that w. a 2way mirror that it can only handle 2 drives failing before seeing data loss but is that 2 drives between both JBODS or is that 2 driver
per JBOD? Also I know that if 1 JBOD were to completely go offline that I would need a total of 3 JBODS in order for vms,etc to not be affected but what is the expected behavior. A jbod goes offline and we lose vms but data is not loss? Once the jbod
comes back data will be back to normal?

if you are going to mirror the 2 of them yes
What are the resiliency levels provided by Enclosure Awareness?
Storage Space Configuration
All Configurations are enclosure aware
Enclosure or JBOD Count / Failure Coverage
Two JBOD
Three JBOD
Four JBOD
2-way Mirror
1 Disk
1 Enclosure
1 Enclosure
3-way Mirror
2 disk
1 Enclosure + 1 Disk
1 Enclosure + 1 Disk
Dual Parity
2 disk
2 disk
1 Enclosure + 1 Disk
REF: Storage Spaces Frequently Asked Questions (FAQ)
Storage Spaces, JBODs, and Failover Clustering – A Recipe for Cost-Effective,
Highly Available Storage
This post is provided AS IS with no warranties or guarantees, and confers no rights.
~~~
Questo post non fornisce garanzie e non conferisce diritti

Space Allocated and Space used for Table.

Hi,
Is there any way, we can find Space Allocated and Space used for Table wise.
I know USER_TABLESPACES help use to find table space wise. But I would like to know, the space utilized by each table in the specific table space.

Check this link from Tom Kyte about it.
http://asktom.oracle.com/pls/asktom/f?p=100:11:2092735390859556::::P11_QUESTION_ID:231414051079

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If Other (the yellow bar) is too big something is corrupted. The only solution (that I know of) is to restore from your most recent backup using iTunes (see http://support.apple.com/kb/ht1766).

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Another possibility is exporting to MXF OP1a using the AVC-I codec. It's not lossless, but it is Master quality. Plus the file size is a LOT smaller, so it may suit your needs.

HT1296 is there a way to NOT synch album artwork - I'd rather save the space for music...

is there a way to NOT synch album artwork - I'd rather save the space for music...I have an Ipod Nano 4GB (yes it's old)

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Note that the artwork associated with your albums is probably less than 1% of the size of your media files themselves.

Quick way to change "Optimize for" setting when "mirror displays" is on?

Is there a quick way to change "Optimize for" setting when "mirror displays" is on?
I have two displays on my Mac Mini for totally different areas; I can't see the first monitor when I'm on the second. One is 1280x1024, one is 1920x1200. As I switch fairly often I'm wondering if there is a built-in or 3rd-party-utility way to quickly toggle the "optimize for" setting that is under "System Preferences" -> "Displays" -> "Display" tab -> "Optimize for:" dropdown box.
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I'm thinking that, Display Menu from the Mac App Store will help.

Have two ipads one account, to facetime with wifes ipad i need to make a differant id the way i understand it,my ipad has a space for another contact but on hers it only has sign in and pass. do i cancel my id on hers and enter her own email

on her ipad there is only my id and a space for password, do I cancel my id and put in her email , then and her email to my ipad where it says another contact, confused;

Apps are forever tied to the Apple ID under which they were purchased. If your friend wants to be able to manage apps on their device using their own Apple ID, they will need to delete all the apps purchased using your Apple ID and buy their own.
Hopefully, you just updated your own Apple ID with the new email and didn't make the mistake of creating a new Apple ID. If you created a new ID, stop using it now, don't buy anything using it and go back and update the ID under which you purchased your apps.

Allocation of disc space for CS5 on custom 6-core PC

I have upgraded to a 6 core PC with Windows 7 Professional as follows:
ASUS P9X78 Deluxe Motherboard
Intel i7 3930 CPU
DDR3 1600 32G RAM
1 Samsung MZ-7PD256BW R 256G SSD (C drive)
2 1TB 7200rpm SATA HD RAID (E drive)
2 1TB 7200rpm SATA HD RAID (F drive)
Nvidia GTX660 2G Video
The D drive was allocated to the LG Super Multi DISC drive but, apart from the C drive, the others can be realloacted.
I understand that that read/writes to SSD drives should be minimized if possible for a longer life span. My Documents can be reallocated from the SSD drive to one of the other 2 drives. I have started a project to find that the Scratch Discs are subject to allocation to My Documents under what appears to be a Private restriction.
I do not have experience on the better allocation of resources for speed on the 6-core PC as shown. I have spent a number of years allowing the default allocation of files while attempting to distribute concurrent reads and writes to 4 1TB drives on a 4-core PC without much experience.
Perhaps some allocations are fixed by Premier Pro. How should I allocate the following on the E and F drives?
- Source files for Video and Audio
- Project Files
- Scratch Discs
- Preview Files
- Encoded Files
- Rendered Files

I prefer to do that outside of Premiere and use http://www.scootersoftware.com/moreinfo.php?zz=moreinfo_compare
It allows me to compare the contents of different directories on different drives or computers, even over a network or VPN and copy left to right, right to left or synchronize left and right. For me that is far easier.
Example, I have CS5.5 installed with various plug-ins. Now I install CS6 and want to continue using the same plug-ins. I then use BeyondCompare to find the missing plug-ins in the fresh CS6 installation and copy from CS5.5 to CS6 those missing plug-ins. That makes all those plug-ins available in CS6 as well, instead of reinstalling them again for CS6 only and entering my license keys for all of them. Much faster and easier.
Another example. I have a lot of audio tracks on my old system and I don't want them on the server, but do want them on my new system, so I use synchronize to keep them in sync. We are talking about more than 100 GB of material. In just a few clicks both machines are synchronized and it has the side effect of being a nice backup. Now I add a new album to machine A and synchronize with machine B, job done. Material is available on both machines.

A workaround to get open documents in different Spaces to the allocated PS space

A small workaround for Spaces CS5 Mac.
If you have CS5 documents spread over different Spaces due to clicking them in the finder and want to get them all back in to the allocated PS Space, here's a workaround.
You do need one doc open in the correct space I'm afraid for it to work. Create a new doc in there if you have to. I tend to leave one small doc open in the right Space all the time now.
Go to the allocated PS space. Select the menu option "Consolidate all to tabs" from the Window>Arrange menu.
This will bring all the open docs from their spaces to the correct space as tabs.
That might be enough for you but you can't drag adjustments layers and layers with alphas etc to another doc in Tab view, something I do all the time when I'm retouching 20-30 shots and I'm trying to match them.
Hard to do that with tab view obviously.
Next select "Float all in windows" and you'll have your docs viewable, side by side in the right space.
If you assign a key command to those options, it becomes a quick tap 1-2 and you're done.
As far as I can tell, if you want floating windows, and all your docs in the right place, and don't want to open your images from the PS open dialogue (who does when you have 6 windows of 50 images on your dual 30" monitor setup?) then this will do it.
It's not great for all things but it's better than "It's all Apple's fault"

there is certainly no built in way to do it. In fact Dock Spaces is the only program I've ever heard of that allows you to have different docks in different spaces. if it can't do it, it's impossible.

How to calculate the percentage of free space for a table in Oracle

okay, I am a little confused here. I have been searching the web and looking at a lot of documents. What I basically want to find out is this, how do I calculate the difference between the number of bytes a table is using and the total bytes allocated to a table space (going that way to get percent free for a particular table). So I need a byte count of a table and total table space and the percentage difference. I have been looking at the DBA_TABLES DBA_TABLESPACES and DBA_SEGMENTS views. I have tried to calculated the space as num_rows * avg_row_len (if I am wrong, let me know). I have been trying to compare that calculation to the number in DBA_TABLESPACES and DBA_SEGMENTS. I am just looking for the total space allocated to the table space that the table sits in (seem logical right now) to make the percentage value work. Thus I want to be able to track the table as it grows as compated to the table space it sits in to see a value as it changes over time (days, weeks, etc.) each time I run this script I am working on.
Can someone get me straight and help me to find out if I am looking in the right places. Any advice would help.
Edward

You can use a little modified version of dbms_space from Tom, show_space. Have a look,
SQL> create table test222 as select * from all_objects;
Table created.
SQL> delete from test22 where rownum<=100;
delete from test22 where rownum<=100
ERROR at line 1:
ORA-00942: table or view does not exist
SQL> delete from test222 where rownum<=100;
100 rows deleted.
SQL> analyze table test222 compute statistics;
Table analyzed.
SQL> create or replace procedure show_space
2 ( p_segname in varchar2,
3    p_owner   in varchar2 default user,
4    p_type    in varchar2 default 'TABLE',
5    p_partition in varchar2 default NULL )
6 -- this procedure uses authid current user so it can query DBA_*
7 -- views using privileges from a ROLE and so it can be installed
8 -- once per database, instead of once per user that wanted to use it
9 authid current_user
10 as
11      l_free_blks                 number;
12      l_total_blocks              number;
13      l_total_bytes               number;
14      l_unused_blocks             number;
15      l_unused_bytes              number;
16      l_LastUsedExtFileId         number;
17      l_LastUsedExtBlockId        number;
18      l_LAST_USED_BLOCK           number;
19      l_segment_space_mgmt        varchar2(255);
20      l_unformatted_blocks number;
21      l_unformatted_bytes number;
22      l_fs1_blocks number; l_fs1_bytes number;
23      l_fs2_blocks number; l_fs2_bytes number;
24      l_fs3_blocks number; l_fs3_bytes number;
25      l_fs4_blocks number; l_fs4_bytes number;
26      l_full_blocks number; l_full_bytes number;
27
28      -- inline procedure to print out numbers nicely formatted
29      -- with a simple label
30      procedure p( p_label in varchar2, p_num in number )
31      is
32      begin
33          dbms_output.put_line( rpad(p_label,40,'.') ||
34                                to_char(p_num,'999,999,999,999') );
35      end;
36 begin
37     -- this query is executed dynamically in order to allow this procedure
38     -- to be created by a user who has access to DBA_SEGMENTS/TABLESPACES
39     -- via a role as is customary.
40     -- NOTE: at runtime, the invoker MUST have access to these two
41     -- views!
42     -- this query determines if the object is a ASSM object or not
43     begin
44        execute immediate
45            'select ts.segment_space_management
46               from dba_segments seg, dba_tablespaces ts
47              where seg.segment_name      = :p_segname
48                and (:p_partition is null or
49                    seg.partition_name = :p_partition)
50                and seg.owner = :p_owner
51                and seg.tablespace_name = ts.tablespace_name'
52               into l_segment_space_mgmt
53              using p_segname, p_partition, p_partition, p_owner;
54     exception
55         when too_many_rows then
56            dbms_output.put_line
57            ( 'This must be a partitioned table, use p_partition => ');
58            return;
59     end;
60
61
62     -- if the object is in an ASSM tablespace, we must use this API
63     -- call to get space information, else we use the FREE_BLOCKS
64     -- API for the user managed segments
65     if l_segment_space_mgmt = 'AUTO'
66     then
67       dbms_space.space_usage
68       ( p_owner, p_segname, p_type, l_unformatted_blocks,
69         l_unformatted_bytes, l_fs1_blocks, l_fs1_bytes,
70         l_fs2_blocks, l_fs2_bytes, l_fs3_blocks, l_fs3_bytes,
71         l_fs4_blocks, l_fs4_bytes, l_full_blocks, l_full_bytes, p_partition);
72
73       p( 'Unformatted Blocks ', l_unformatted_blocks );
74       p( 'FS1 Blocks (0-25) ', l_fs1_blocks );
75       p( 'FS2 Blocks (25-50) ', l_fs2_blocks );
76       p( 'FS3 Blocks (50-75) ', l_fs3_blocks );
77       p( 'FS4 Blocks (75-100)', l_fs4_blocks );
78       p( 'Full Blocks        ', l_full_blocks );
79    else
80       dbms_space.free_blocks(
81         segment_owner     => p_owner,
82         segment_name      => p_segname,
83         segment_type      => p_type,
84         freelist_group_id => 0,
85         free_blks         => l_free_blks);
86
87       p( 'Free Blocks', l_free_blks );
88    end if;
89
90    -- and then the unused space API call to get the rest of the
91    -- information
92    dbms_space.unused_space
93    ( segment_owner     => p_owner,
94      segment_name      => p_segname,
95      segment_type      => p_type,
96      partition_name    => p_partition,
97      total_blocks      => l_total_blocks,
98      total_bytes       => l_total_bytes,
99      unused_blocks     => l_unused_blocks,
100      unused_bytes      => l_unused_bytes,
101      LAST_USED_EXTENT_FILE_ID => l_LastUsedExtFileId,
102      LAST_USED_EXTENT_BLOCK_ID => l_LastUsedExtBlockId,
103      LAST_USED_BLOCK => l_LAST_USED_BLOCK );
104
105      p( 'Total Blocks', l_total_blocks );
106      p( 'Total Bytes', l_total_bytes );
107      p( 'Total MBytes', trunc(l_total_bytes/1024/1024) );
108      p( 'Unused Blocks', l_unused_blocks );
109      p( 'Unused Bytes', l_unused_bytes );
110      p( 'Last Used Ext FileId', l_LastUsedExtFileId );
111      p( 'Last Used Ext BlockId', l_LastUsedExtBlockId );
112      p( 'Last Used Block', l_LAST_USED_BLOCK );
113 end;
114
115 /
Procedure created.
SQL> desc show_space
PROCEDURE show_space
Argument Name                  Type                    In/Out Default?
P_SEGNAME                      VARCHAR2                IN
P_OWNER                        VARCHAR2                IN     DEFAULT
P_TYPE                         VARCHAR2                IN     DEFAULT
P_PARTITION                    VARCHAR2                IN     DEFAULT
SQL> set serveroutput on
SQL> exec show_space('TEST222','SCOTT');
BEGIN show_space('TEST222','SCOTT'); END;
ERROR at line 1:
ORA-00942: table or view does not exist
ORA-06512: at "SCOTT.SHOW_SPACE", line 44
ORA-06512: at line 1
SQL> conn / as sysdba
Connected.
SQL> grant sysdba to scott;
Grant succeeded.
SQL> conn scott/tiger as sysdba
Connected.
SQL> exec show_space('TEST222','SCOTT');
BEGIN show_space('TEST222','SCOTT'); END;
ERROR at line 1:
ORA-06550: line 1, column 7:
PLS-00201: identifier 'SHOW_SPACE' must be declared
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored
SQL> exec scott.show_space('TEST222','SCOTT');
PL/SQL procedure successfully completed.
SQL> set serveroutput on
SQL> exec scott.show_space('TEST222','SCOTT');
Unformatted Blocks .....................               0
FS1 Blocks (0-25) .....................               0
FS2 Blocks (25-50) .....................               1
FS3 Blocks (50-75) .....................               0
FS4 Blocks (75-100).....................               1
Full Blocks        .....................             807
Total Blocks............................             896
Total Bytes.............................       7,340,032
Total MBytes............................               7
Unused Blocks...........................              65
Unused Bytes............................         532,480
Last Used Ext FileId....................               4
Last Used Ext BlockId...................           1,289
Last Used Block.........................              63
PL/SQL procedure successfully completed.
SQL>http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:5350053031470
I use this to find the space allocations.
Just read your post again,this is not going to show you the percentage of the free/used space. This is going to be the number of blocks which are free/used. For the growth trend, you can look at (in 10g) Oracle EM. It has added now,Segment Growth Trend report which can show you for each object,comparing to the allocated space to the object,how much space is being used by it.
HTH
Aman....

Allocation of space for 3-Way Mirror

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