What kind of hardware is it running on ? What OS ? Here's my performance issue story.
I thought I was having issues myself with dynamic files. We had switched over to Linux about 6 months ago. Things were going fine until I started to run our 'purges'. They would take the system down to its knees. Anyway, I finally found out that the problem was some Qlogic HBA's that we have connecting a Clariion disk array. My VAR loaned me some Emulex cards this week. I switched the Qlogic for Emulex and the problem disappeared ! The iowait reading on the system would go to about 100% when doing heavy disk writes - forget dynamic files - just plain file copies (1/2 gig files) in Linux to the Clariion. The copy would complete and the iowait would remain up at 100% for sometimes up to a minute afterwards. Our /var/log/messages file would get loaded with 'QUEUE FULL' errors from the qla2300 driver. Doing the same copy with the Emulex cards cause iowait to hit about 74%. However, as soon as the copy is complete, the iowait goes back down to next to nothing without any kind of major freeze up. This may not be your issue at all. I would suggest copying of a large file at the OS level using the disk that the dynamic files are on as the target. See if this has the same impact on the performance. If so, then the issue is not dynamic files after all - its OS/hardware related. A lesson to anyone considering Linux - stay away from Qlogic HBA's - they suck in a major way and the company denys any problems and says that they are stable on Linux. They are not ! Anthony Dzikiewicz -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of gerry-u2ug Sent: Friday, May 06, 2005 7:25 PM To: u2-users@listserver.u2ug.org Subject: RE: [U2] Dynamic File Performance Thanks Anthony. I was under the impression that a split was a lot more involved than that. The situation is that a client is experiencing periodic system 'crawl' where everything slows right down and the login process is completely stopped. One thing that I noticed is that there have been a number files converted to dynamic files and I was wondering if this could be the culprit. You mentioned that there shouldn't be much split/merge with constant size files - what about very dynamic sized files ? I noticed that they have converted a number of work/scratch files to dynamic whcih I would think is not such a good idea. Gerry -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Anthony W. Youngman Sent: Friday, May 06, 2005 05:41 PM To: u2-users@listserver.u2ug.org Subject: Re: [U2] Dynamic File Performance In message <[EMAIL PROTECTED]>, gerry-u2ug <[EMAIL PROTECTED]> writes >Hi > >I am looking for a reference regarding performance/monitoring of >dynamic files in universe. In particular I am looking for a way to >gauge the impact of dynamic files on system performance. In what way? I use dynamic files all the time, and we don't notice much of an impact. >Is there some way to know exactly when a file splits/merges, hw long it >takes and the impact on the system ? > Not that I know of. If your file remains roughly constant in size, it's unlikely to split or merge much. It'll split when growing and merge if it shrinks *significantly*. As for how long it takes, the whole point of dynamic files is that it's almost instantaneous. Assuming we have the standard 2K bucket, the chances are a split takes whatever time it takes to write 4K to disk - the rest of the overhead is negligible ... Cheers, Wol -- Anthony W. Youngman <[EMAIL PROTECTED]> 'Yings, yow graley yin! Suz ae rikt dheu,' said the blue man, taking the thimble. 'What *is* he?' said Magrat. 'They're gnomes,' said Nanny. The man lowered the thimble. 'Pictsies!' Carpe Jugulum, Terry Pratchett 1998 Visit the MaVerick web-site - <http://www.maverick-dbms.org> Open Source Pick ------- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ ------- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.11.1 - Release Date: 5/2/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.11.1 - Release Date: 5/2/2005 ------- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/
