Buffer data before chart it and block size
I hope you can help me with this situation because I have been stoped in this situation for two days and I think that I won't see the light in the short time and the time is a scarce resource.
I want to use a NI DaqCard-AI-16XE-50 ( 20KS/s accordig to specifications). To acquired data in DasyLab I've been using OPC DA system but when I try get a chart from the signal I get awfull results.
I guess the origin of the problem is the PC is not powerfull to generate a chart in real time, so Is there a block to save the data, then graph the data without use "Write Data" Block to avoid write data to disk?
Another cause of the problem it could be an incorrect set value of Block size, but in my piont of view with the 10Khz, and 4096 of block size is more than neccesary to acquire a signal of 26[Hz] (showing in the photo). If I reduce the block size to 1 the signal showing in the graph is a constant of the first value acquire. Why could be this situation?
Thanks in advance for your answers,
Solved!
Go to Solution.
Attachments:
data from DAQcard.PNG 95 KB
Is there someone who can help me
I connect CN606TC2 and Dasylab 11... using the RS232 cable, and have done the instruction manual of the book cn606tc2.
In dasylab RS232 module, there is a box:
1). Measurement data request,
2). Measurement data format ...
what should I write in the box is so modules dasylab Digital meters can be read from CN606TC2.
To start communication, the Command Module must send alert code ASCII [L] hex 4C.
Commands requesting data from the scannerCN606TC2)
ASCII [A] hex 41 = Zones/ Alarms/ Scan time
ASCII [M] hex 4D = Model/ Password/ ID#/ # of zones
ASCII [S] hex 53 = Setpoints
ASCII [T] hex 54 = Temperature
I did not understand the program and the ASCII code.
I send [T] in the RS232 monitor and restore dasylab 54.
I am very grateful for your help
Similar Messages
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Tablespaces and block size in Data Warehouse
We are preparing to implement Data Warehouse on Oracle 11g R2 and currently I am trying to set up some storage strategy - unfortunately I have very little experience with that. The question is what are general advices in such considerations according table spaces and block size? I made some research and it is hard to find some clear answer, there are resources advising that block size is not important and can be left small (8 KB), others state that it is crucial and should be the biggest possible (64KB). The other thing is what part of data should be placed where? Many resources state that keeping indexes apart from its data is a myth and a bad practice as it may lead to decrease of performance, others say that although there is no performance benefit, index table spaces do not need to be backed up and thats why it should be split. The next idea is to have separate table spaces for big tables, small tables, tables accessed frequently and infrequently. How should I organize partitions in terms of table spaces? Is it a good idea to have "old" data (read only) partitions on separate table spaces?
Any help highly appreciated and thank you in advance.Wojtus-J wrote:
We are preparing to implement Data Warehouse on Oracle 11g R2 and currently I am trying to set up some storage strategy - unfortunately I have very little experience with that. With little experience, the key feature is to avoid big mistakes - don't try to get too clever.
The question is what are general advices in such considerations according table spaces and block size? If you need to ask about block sizes, use the default (i.e. 8KB).
I made some research and it is hard to find some clear answer, But if you get contradictory advice from this forum, how would you decide which bits to follow ?
A couple of sensible guidelines when researching on the internet - look for material that is datestamped with recent dates (last couple of years), or references recent - or at least relevant - versions of Oracle. Give preference to material that explains WHY an idea might be relevant, give greater preference to material that DEMONSTRATES why an idea might be relevant. Check that any explanations and demonstrations are relevant to your planned setup.
The other thing is what part of data should be placed where? Many resources state that keeping indexes apart from its data is a myth and a bad practice as it may lead to decrease of performance, others say that although there is no performance benefit, index table spaces do not need to be backed up and thats why it should be split. The next idea is to have separate table spaces for big tables, small tables, tables accessed frequently and infrequently. How should I organize partitions in terms of table spaces? Is it a good idea to have "old" data (read only) partitions on separate table spaces?
It is often convenient, and sometimes very important, to separate data into different tablespaces based on some aspect of functionality. The performance thing was mooted (badly) in an era when discs were small and (disk) partitions were hard; but all your other examples of why to split are potentially valid for administrative. Big/Small, table/index, old/new, read-only/read-write, fact/dimension etc.
For data warehouses a fairly common practice is to identify some sort of aging pattern for the data, and try to pick a boundary that allows you to partition data so that a large fraction of the data can eventually be made read-only: using tablespaces to mark time-boundaries can be a great convenience - note that the tablespace boundary need not match the partition boudary - e.g. daily partitions in a monthly tablespace. If you take this type of approach, you might have a "working" tablespace for recent data, and then copy the older data to "time-specific" tablespace, packing it and making it readonly as you do so.
Tablespaces are (broadly speaking) about strategy, not performance. (Temporary tablespaces / tablespace groups are probably the exception to this thought.)
Regards
Jonathan Lewis -
DASYLAB QUERIES on Sampling Rate and Block Size
HELP!!!! I have been dwelling on DASYLAB for a few weeks regarding certain problems faced, yet hasn't come to any conclusion. Hope that someone would be able to help.Lots of thanks!
1. I need to have more data points, thus I increase the sampling rate(SR). When sampling rate is increased, Block size(BS) will increase correspondingly.
For low sampling rate (SR<100Hz) and Block size of 1, the recorded time in dasy and the real experimental time is the same. But problem starts when SR>100Hz for BS=1. I realized that the recorded time in dasylab differs from the real time. To solve the time difference problem, I've decided to use "AUTO" block size.
Qn1: Is there any way to solve the time difference problem for high SR?
Qn2: For Auto Block Size, Is the recorded result in dasylab at one time moment the actual value or has it been overwritten by the value from the previous block when AUTO BS is chosen.
2. I've tried getting the result for both BS=1 and when BS is auto. Regardless of the sampling rate, the values gotten when BS=1 is always larger than that of Auto Block size. Qn1: Which is the actual result of the test?
Qn2: Is there any best combination of the block size and sampling rate that can be used?
Hope someone is able to help me with the above problem.
Thanks-a-million!!!!!
Message Edited by JasTan on 03-24-2008 05:37 AMGenerally, the DASYLab sampling rate to block size ratio should be between 2:1 and 10:1.
If your sample rate is 1000, the block size should be 500 to no smaller than 100.
Very large block sizes that encompass more than 1 second worth of data often cause display delays that frustrate users.
Very small block sizes that have less than 10 ms of data cause DASYLab to bog down.
Sample rate of 100 samples / second and a block size of 1 is going to cause DASYLab to bog down.
There are many factors that contribute to performance, or lack there of - the speed and on-board buffers of the data acquisition device, the speed, memory, and video capabilities of the computer, and the complexity of the worksheet. As a result, we cannot be more specific, other than to provide you with the rule of thumb above, and suggest that you experiment with various settings, as you have done.
Usually the only reason that you want a small block size is for closed loop control applications. My usual advice is that DASYLab control is around 1 to 10 samples/second. Much faster, and delays start to set in. If you need fast, tight control loops, there are better solutions that don't involve Microsoft Windows and DASYLab.
Q1 - without knowing more about your hardware, I cannot answer the question, but, see above. Keep the block size ratio between 2:1 and 10:1.
Q2 - without knowing more about your hardware, and the driver, I'm not sure that I can fully answer the question. In general, the DASYLab driver instructs the DAQ device driver to program the DAQ device to a certain sampling rate and buffer size. The DASYLab driver then retrieves the data from the intermediate buffers, and feeds it to the DASYLab A/D Input module. If the intermediate buffers are too small, or the sample rate exceeds the capability of the built-in buffers on the hardwar, then data might be overwritten. You should have receive warning or error messages from the driver.
Q3 - See above.
It may be that your hardware driver is not configured correctly. What DAQ device, driver, DASYLab version, and operating system are you using? How much memory do you have? How complex is your worksheet? Are you doing control?
Have you contacted your DASYLab reseller for more help? They should know your hardware better than I do.
- cj
Measurement Computing (MCC) has free technical support. Visit www.mccdaq.com and click on the "Support" tab for all support options, including DASYLab. -
Raid 0 (Stripe) for OS X boot disk? Best Performance and block size
Hi,
so this is a new thread to an older question I had and would like some feedback on;
I have a new Mac Pro with 4 matched 1TB caviar black drives. I WILL be doing Full Time-Machine Backups, as well as an independant full-system backup regularly.
That being said, I have 4 drives open and am looking for suggestions. I am leaning toward 2 sets or stripes (one for the OS and one for 'work space', the former with a 32k stripe block size, the latter with 64k (will hold video, audio, scratch, and, yes, Games).
Does this sound alright? Is there an issue with Striping the boot drive? Is the block size or 32 (or 64) optimal?
Thanks!
DanHi D# Shooter, regarding your question,
D3 Shooter wrote:
You brought to mind something I did not take into consideration, Time Machine. I really like the simplicity of TM as it saved me once before. So, could you tell me, for photo files, some video, how much does the striping (% wise) improve the accessing and filing of such files compared to no striping but, using internal drives (7200/WD/1TB/Caviar)? I have not done striping before and want to weigh in because of the back up storage issues now. Thanks.
J_ust give it a try and see if it is worth it for you_.
Striping:
• just enhances (reduces the access/transfer) because in practice the access is distributed in parallel across several DDM's (Old school but it works great!). I think for video and file work the advantage is that you can access the whole object sooner (rather than faster).
• this distribuition also reduces a load of old style queing on the device ove rthe path. THis was resolved in the late 1980's so no reall rocket science here.
the issues with striping are few and basically over all the raid implementations (except JBOD which of course is not raid) when compared to a single spindle. The discussions are enormous and plentiful via google and experiences and opinions vary widely.
Fir the I.T. peole its the advantage they get for access using a smart disk controller that caches goosies like indexes and stuff so that they can sustain a zillion trivial transactions/sec (i.e. banking & internet stuff).. stuff that is of no interest to me
For the creative people and many applications that are BLOB's (like video, film and remote sensing objects) getting use of the objects sooner (not faster) is of prime importance for workflow efficiencies. If you have this need then striping stiff across disks is for you!
TIMEMACHINE.app works fine as it seems fairly agnostic to whats implemented under the disk file system. MY issue with time machine is that I don't want it looking after my production stuff, only to keep an eye on my admin I.T. type stuff such as ~/ and data data files.
As posted on ths thread:
• availability is the major concern with any file system (cloud or raid or other). RAID with parity schemes and double parity schemes (Raid1,,3,5,6) and implementations such as RAID6+ LSF (log structured file) are all wonderful for this business workflows that need it.
• timely access in a workflow is another
• cost benefits are another
However a *great benefit* for me of *consolidating small storage components under one huge file system is that you dont have to COPY any thing around*. THis is marvelous especially when you think you have to move 2TB's of stuff from one place to anther. THis a takes a lot of time with elcheapo didks that dont have fast interfaces such as SATA/SAS of FC for example.
As always and has been addressed by others on this thread (Hatter) if you lose a component storage device the whole file system is hosed or severely degraded unless you spend a lot of money on full ranks of DDMs with hot spares and a very good RAID controller card. Again its money.
YEah sure you can carry some PARITY RAID implementation around across 3 didks but the storage capacity usage is dreadful. THis is why more complex RAID implemntatiosn are in groups of 10+ dDMs.. (yep poepl can argue.. but this is the mainstream).
My external disk arrays are merely two LUNs (SAS DOMAINSA) that have two file systems implemented using 2 x 4TB 1TBs DDMS - all RAID0 - no parity (no availability) - I just want speed. I look after my own "availability" withm= my archive solution. If the operation dies, I stat again. I'm happy wi that. RAID 5 has write penalty performace hits (well known +update in place+), , RAID 6+ is lousy for huge objects but good for I.T. but ok if you lose two disks in a stripe (RANK).
They all have their flaws... and mirroring a RAID0 (RAID1/0) seems to be popular with storage vendors because they can see you more disk and thats proper business workflow depends on it.
However you can achieve this stuff if you change your workflow slightly.
Other than these the rest is tech specs and stuff under the cover.
So you what is right for you and your business.
I dont like spending money on nasty elcheapo FW800 LeCIE disk enclosures with the their junky components and their ilk having been done badly on several corrupted devices and lsing TB;s of content - this is why I invested in a high speed LTO4 ULtrium data tape archive solution.
sorry for long post..
w -
Raid storage usage and block size
We have two XServe RAID units Raid 5 and we are adding a new 16 bay ACNC raid with 16 1.5TB drives in Raid 6 + Hot Spare. I initialized the Raid 6 with 128K block size. The total data moving from the older raid volumes is around 5.7TB, but on the new Raid it is taking around 7.4TB of space. Is this due to the 128K block size? This is a prepress server so most of the files are quite large, but there may be lots of small files as well.
Hi
RAID 0 does indeed offer best performance, however if any one drive of the striped set fails you will lose all your data. If you have not considered a backup strategy now would be the time to do so. For redundancy RAID 1 Mirror might be a better option as this will offer a safety net in case of a single drive failure. A RAID is not a backup and you should always consider a workable backup strategy.
Purchase another 2x1TB drives and you could consider a RAID 10? Two Stripes mirrored.
Not all your files will be large ones as I'm guessing you'll be using this workstation for the usual mundane matters such as email etc? Selecting a larger block size with small file sizes usually decreases performance. You have to consider all applications and file sizes, in which case the best block size would be 32k.
My 2p
Tony -
* This was posted in the "Installation" Thread, but I copied it here to see if I can get more responses, Thank you.*
Hello,
I am about to set up a new Oracle 10.2 Database server. In the past, I used RAID5 since 1) it was a fairly small database 2) there were not alot of writes 3) high availability 4) wasted less space compared to other RAID techniques.
However, even though our database is still small (around 100GB), we are noticing that when we update our data, the time it takes is starting to grow to a point whereby the update that used to take about an hour, now takes 10-12 hours or more. One thing we noticed that if we created another tablespace which had a block size of 16KB versus our normal tablespace which had a block size of 8KB, we almost cut the update time in half.
So, we decided that we should really start from scratch on a new server and tune it optimally. Here are some questions I have:
1) Our server is a DELL PowerEdge 2850 with 4x146GB Hard Drives (584GB total). What is the best way to set up the disks? Should I use RAID 1+0 for everything? Should I use ASM? If I use ASM, how is the RAID configured? Do I use RAID0 for ASM since ASM handles mirroring and striping? How should I setup the directory structure? How about partitioning?
2) I am installing this on Linux and when I tried on my old system to use 32K block size, it said I could only use 16K due to my OS. Is there a way to use a 32K block size with Linux? Should I use a 32K block size?
Thanks!Hi
RAID 0 does indeed offer best performance, however if any one drive of the striped set fails you will lose all your data. If you have not considered a backup strategy now would be the time to do so. For redundancy RAID 1 Mirror might be a better option as this will offer a safety net in case of a single drive failure. A RAID is not a backup and you should always consider a workable backup strategy.
Purchase another 2x1TB drives and you could consider a RAID 10? Two Stripes mirrored.
Not all your files will be large ones as I'm guessing you'll be using this workstation for the usual mundane matters such as email etc? Selecting a larger block size with small file sizes usually decreases performance. You have to consider all applications and file sizes, in which case the best block size would be 32k.
My 2p
Tony -
Transaction execution time and block size
Hi,
I have Oracle Database 11g R2 64 bit database on Oracle Linux 5.6. My system has ONE hard drive.
Recently I experimented with 8.5 GB database in TPC-E test. I was watching transaction time for 2K,4K,8K Oracle block size. Each time I started new test on different block size, I would created new database from scratch to avoid messing something up (each time SGA and PGA parameters ware identical).
In all experiments a gave to my own tablespace (NEWTS) different configuration because of oracle block-datafile size limits :
2K oracle block database had 3 datafiles, each 7GB.
4K oracle block database had 2 datafiles, each 10GB.
8K oracle block database had 1 datafile of 20GB.
Now best transaction (tranasaction execution) time was on 8K block, little longer tranasaction time had 4K block, but 2K oracle block had definitly worst transaction time.
I identified SQL query(when using 2K and 4K block) that was creating hot segments on E_TRANSACTION table, that is largest table in database (2.9GB), and was slowly executed (number of executions was low compared to 8K numbers).
Now here is my question. Is it possible that multiple datafiles are reasone for this low transaction times. I have AWR reports from that period, but as someone who is still learning things about DBA, I would like to asq, how could I identify this multi-datafile problem (if that is THE problem), by looking inside AWR statistics.
THX to all.>
It's always interesting to see the results of serious attempts to quantify the effects of variation in block sizes, but it's hard to do proper tests and eliminate side effects.
I have Oracle Database 11g R2 64 bit database on Oracle Linux 5.6. My system has ONE hard drive.A single drive does make it a little too easy for apparently random variation in performance.
Recently I experimented with 8.5 GB database in TPC-E test. I was watching transaction time for 2K,4K,8K Oracle block size. Each time I started new test on different block size, I would created new database from scratch to avoid messing something up Did you do anything to ensure that the physical location of the data files was a very close match across databases - inner tracks vs. outer tracks could make a difference.
(each time SGA and PGA parameters ware identical).Can you give us the list of parameters you set ? As you change the block size, identical parameters DON'T necessarily result in the same configuration. Typically a large change in response time turns out to be due to changes in execution plan, and this can often be associated with different configuration. Did you also check that the system statistics were appropriately matched (which doesn't mean identical cross all databases).
In all experiments a gave to my own tablespace (NEWTS) different configuration because of oracle block-datafile size limits :
2K oracle block database had 3 datafiles, each 7GB.
4K oracle block database had 2 datafiles, each 10GB.
8K oracle block database had 1 datafile of 20GB.If you use bigfile tablespaces I think you can get 8TB in a single file for a tablespace.
Now best transaction (tranasaction execution) time was on 8K block, little longer tranasaction time had 4K block, but 2K oracle block had definitly worst transaction time.We need some values here, not just "best/worst" - it doesn't even begin to get interesting unless you have at least a 5% variation - and then it has to be consistent and reproducible.
I identified SQL query(when using 2K and 4K block) that was creating hot segments on E_TRANSACTION table, that is largest table in database (2.9GB), and was slowly executed (number of executions was low compared to 8K numbers).Query, or DML ? What do you mean by "hot" ? Is E_TRANSACTION a partitioned table - if not then it consists of one segment, so did you mean to say "blocks" rather than segments ? If blocks, which class of blocks ?
Now here is my question. Is it possible that multiple datafiles are reasone for this low transaction times. I have AWR reports from that period, but as someone who is still learning things about DBA, I would like to asq, how could I identify this multi-datafile problem (if that is THE problem), by looking inside AWR statistics.On a single disc drive I could probably set something up that ensured you got different performance because of different numbers of files per tablespace. As SB has pointed out there are some aspects of extent allocation that could have an effect - roughly speaking, extents for a single object go round-robin on the files so if you have small extent sizes for a large object then a tablescan is more likely to result in larger (slower) head movements if the tablespace is made from multiple files.
If the results are reproducible, then enable extended tracking (dbms_monitor, with waits) and show us what the tkprof summaries for the slow transactions look like. That may give us some clues.
Regards
Jonathan Lewis -
Specifying segments and block size manaually
Hi, just a quick question,
But could anyone help me understand why someone may manually add segments to a table space (or is it a data file they would be added to) ? does auto extend not take care of this?
And secondly ... why would you increase or decrease the block size of a segment?... is this because you may have small or large sized rows within a table and want a block size to acompany this?
Any help would be appriciatedHi,
In Oracle free space can be managed automatically or manually,You specify automatic segment-space management when you create a locally managed tablespace
Free space can be managed automatically inside database segments. The in-segment free/used space is tracked using bitmaps, as opposed to free lists. Automatic segment-space management offers the following benefits:
-Ease of use
-Better space utilization, especially for the objects with highly varying size rows
-Better run-time adjustment to variations in concurrent access
-Better multi-instance behavior in terms of performance/space utilization
For manually managed tablespaces, two space management parameters, PCTFREE and PCTUSED, enable you to control the use of free space for inserts and updates to the rows in all the data blocks of a particular segment. Specify these parameters when you create or alter a table or cluster (which has its own data segment). You can also specify the storage parameter PCTFREE when creating or altering an index (which has its own index segment).
see this link
http://download.oracle.com/docs/cd/B10500_01/server.920/a96524/b_deprec.htm#634923 :) -
Let's say that I have an RSA key pair that has been generated in a keystore using the keytool utility.
I am now accessing this key pair through some java code (using the Keystore class) and I want to encrypt/decrypt data using this public/private key.
In order to encrypt/decrypt arbitray length data, I need to know the maximum block size that I can encrypt/decrypt.
Based upon my experiment, this block size seems to be the size of the key divided by 8 and minus 11.
But how can I determine all that programatically when the only thing that I have is the keystore?
I did not find a way to figure out the size of the key from the keystore (unless it can be computed from the RSA exponent or modulus, but this is where my knowledged of RSA keys stops) and I did not find a way to figure out where this "magic" number 11 is coming from.
I can always encrypt 1 byte of data and look at the size of the result. This will give me the blocksize and the key size by multiplying it by 8. But it means that I always need the public key around to compute this size (I cannot do it if I have only the private key).
And this is not helping much on the number 11 side.
Am I missing something obvious?
Thanks.It is probably a bug. A naive implementation of RSA key generation that would exhibit this bug would work as follows (I'm ignoring the encrypt and decrypt exponents intentionally):
input: an rsa modulus bit size k, k is even:
output: the rsa modulus n.
k is even, so let k=2*l
step1: generate an l bit prime p, 2^l(-1) < p < 2^l
step2: generate another l bit prime q, 2^l(-1) < q < 2^l
step3: output n = p*q
Now the above might seem reasonable, but when you multiply the inequalities you get
2^(2*l -2) < n < 2^(2l)
That lower bound means that n can be 1 bit smaller than you expect.. The correct smallest lower bound for generating the primes p and q is (2^l) / sqrt(2), rounded up to the nearest integer.
I'll bet the IBM code implements something like the first algorithm. -
Stripe Breadth and Block size Allocation..
Hi,
Could anyone please advise me if there is any formula or utility to calculate or to investigate the stripe Breadth or the Block size to be used while creating the pools, I know it differs with the different kind of data to be stored..
It should be a document or a utility that helps with that, I'm still fetching for.
waddah
MacBook Pro Mac OS X (10.4.5) PowerMac G5Check out Andre Aulich's site:
http://www.andre-aulich.de/en/perm/optimized-xsan-settings-for-several-video-fil e-formats
A lot of good testing went into those results. -
How to view or list cluster and block size of an ocfs2 filesystem
Hello all...
Have read ocfs2 user guide and do not see a way to list block or cluster size of an ocfs2 filesystem and additional properties similar to tune2fs -l.
Could someone post a way they have found?man tunefs.ocfs2
-Q, --query query-format
Query the file system for its attributes like block size, label, etc. Query formats are modified ver-
sions of the standard printf(3) formatting. The format is made up of static strings (which may include
standard C character escapes for newlines, tabs, and other special characters) and printf(3) type for-
matters. The list of type specifiers is as follows:
B Block size in bytes
T Cluster size in bytes
N Number of node slots
R Root directory block number
Y System directory block number
P First cluster group block number
V Volume label
U Volume uuid
M Compat flags
H Incompat flags
O RO Compat flags -
Do I need to have data before performing Drag and Drop????
I have gotten drag and drop working with Swing in JDK 1.4b2 using "URL-based" files instead of operating system native files. The way this was accomplished by creating a wrapper class that sub-classed File and would download the contents of the URL to a temporary file and then initiate a normal drag and drop operation using the normal java file mechanisms. However, when you have a large file, the operation can take too long since I am fronting all of the effort at the start of the drag. I would like to be able to delay the need to produce the bytes/files to give to the operating system until after there has been a successful drop, at which point I can do the heavy lifting and raise a dialog telling them that the action is commencing. As best as I can tell, you must have all of the data BEFORE any operation (which could be a potential design flaw!!)
So, is there a way to get a hook that there has been a successful drop to a vm-external drop target before the VM gives the data over? Even if I create my own data flavor (which isn't well documented outside of Text types) won't I still run into the same problems? Am I just overlooking something simple?
Thanks for your help.Hello
I've had the same problem, but take a look at: http://foxtrot.sourceforge.net/
You can use their API to start the long consuming time job (reading files from the network) and also to paint a progress bar, showing the progress in the Event Dispatch Thread.
This is how I've solved my problem:
I've passed a MyTransferable object to the startDrag method of the DragGestureEvent event.
In the getTransferData method of MyTransferable object (that implements Transferable interface) I've used the Worker.post method of their API which reads the file from the network and updates a progress bar.
The API lets the Event Dispatch Thread enter but not return from the listener method (getTransferData in my case), instead rerouting the Event Dispatch Thread to continue dequeuing events from the Event Queue and processing them (repaint the progress bar). Once the worker thread has finished, the Event Dispatch Thread is rerouted again, returning from the listener method. -
I just finished the setup of a RAID striped array of 2 500MB disks, my question is about the RAID block size, is there a noticeable difference in performance by choosing a larger block size than the 32KB default?, I chose 64kb but will 128kb make any noticeable difference?
Are you in the right place? The reason I ask is that you can only ever have one disk inside an MBP.
However, if you're talking about an external drive(s) then it would depend on what you are doing with the drive. For a boot/Photoshop/general drive I would recommedn 32K else a maximum 64K. Otherwise, if you are doing large sequential transfers such as video then a larger block size will help. -
How should be set Index block size in Warehouse databases?
Hi,
We have Warehouse database.
I cannot find out index block size.
1. Where can I get know our index block sizes?
2. How can I enlarge index block sizes? Is it related with tablespace?
After your suggestion do I need increase or set buffer cache keep pool according to block sizes? 2K, 4K, 8K, 16K and 32K can be specified?
could you help me please?
thanks and regards,See the BLOCK_SIZE column in DBA_TABLESPACES.
You can't "increase" the block size. You'd have
a) to allocate DB_xK_cache_size for the new "x"K block size
b) create a new tablespace explicitly specifying the block size in the CREATE TABLESPACE command
c) rebuild your indexes into the new tablespace.
Indexes created in a tablespace with a larger block size have more entries in each block.
You may get better performance.
You may get worse performance.
You may see no difference in performance.
You may encounter bugs.
"increasing block size" is an option to be evaluated and tested thoroughly. It is not, per se, a solution.
Hemant K Chitale
http://hemantoracledba.blogspot.com -
Will block size effect the calc script performance?
Hi Experts,
I have a cube called RCI_LA:RCI_LA, now I have created calc scripts and working fine. But those calc scripts are taking too much time than expected (normally it should not take more than 15 min but those are taking nearly 1 hr or more some calc scripts.)
In database properties I found that block size is 155896 B i.e. 152.KB but this size should be 8 to 100 KB & Block density is 0.72%
If block size exceeds more than 100 KB will it impact the performance of Calc scripts?
I think answer to the above question is “yes”. In this case what should I need to do to improve calc scripts performance?
Could you please share your experience here with me to come out of this problem?
Thanks in advance.
RamI believe Sandeep was trying to say "Dynamic" rather than "Intelligent".
The ideal block size is a factor in all calcs, but the contributing reasons are many (The main three are CPU caching, Data I/O overhead, Index I/O overhead).
Generally speaking, the ideal block size is achieved when you can minimize the combination of Data I/O overhead and Index I/O overhead. For this reason a block size that is too large will incur too much Data I/O, while a block size that is too small will incur too much Index I/O. If your Index file is small, increasing your block size may help, although the commonly acceptible block size is between 8K and 64K in size, this is just a guideline.
In other words, if you test it with something right in the middle and your index file is tiny, you might want to test it with a smaller block size. If your index file is very large (i.e. 400 MB or more), you may want to increase the block size and retest.
Ways to increase/decrease it are also many. Obviously, changing the dense/sparse settings is the main way, but there are some considerations that make this a touchy process. Other ways are to use dynamic calc in the dense dimensions. I say start at the top of your smallest dense dimension and keep the number of DIMENSIONS that you use D-C on limited. Using D-C members in a dense dimension does NOT increase the index file, so it could be considered a "free" reduction in block size -- the penulty is paid on the retrieve side (there is no free ride).
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