> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of ericro
> Sent: Wednesday, March 04, 2009 12:37 PM
> To: [email protected]
> Subject: RE: [U2] Performance monitoring
>
> We use topas, but do you have any techniques for analyzing
> individual user
> sessions to understand what's going on within Universe/the
> OS/the disk?
If you end up determining that you're I/O bound, and you use hashed
files, you might try the following to get a list of poorly sized files:
>CLEAR.FILE DATA STAT.FILE (create it in the user account if not there)
>ACCOUNT.FILE.STATS ALL LOCAL
>SELECT STAT.FILE WITH # FILETYPE "1""19""25""30"
>>SELECT STAT.FILE WITH GRP125 GT GRP100 OR WITH GRP200 GT GRP100
>>SELECT STAT.FILE WITH GRP25 LE GRP100 AND WITH GRP50 LE GRP100 AND
WITH GRP75 LE GRP 100
>>SORT STAT.FILE BY FILENAME FILENAME FILEMOD FILESEP GRP25 GRP50 GRP75
GRP100 GRP125 GRP150 GRP175 GRP200
This will give you a list of every hashed file in an account that has a
large percentage of records in overflow space. I went through all our
files last year, and was able to get the select time for one very large
file from around a minute to 2-5 seconds. I recommend increasing the
separation for files with large and/or lumpy records until you have
nothing or almost nothing in overflow space. This is the FILE.STAT
distribution for a 470MB file with modulo 55001 and separation 16:
Groups 25% 50% 75% 100% 125% 150% 175% 200%
full
0 1455 37715 15630 201 0 0 0
You also never want to use a separation less than the block size of your
storage, and only increase separation in increments of that block size.
In our case that's 4K, corresponding to a separation of 8.
-John
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