[zfs-discuss] Re: ZFS memory and swap usage
Did you say what version of Solaris 10 you were using? I had similar problems on Sol10 U2, booting a database. This involved first initializing the data files (a few Gb), then starting the server(s) which tried to allocate a large chunk of shared memory. This failed miserably since ZFS had gobbled up most memory. But with Sol10 U3, this problem had gone away and ARC memory was quickly released. I found vmstat was convenient for a simple overview of available memory during the process. - Bjorn This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Re: ZFS memory and swap usage
We're running Update 3. Note that the DB _does_ come up, just not in the two minutes they were expecting. If they wait a few moments after their two-minute start-up attempt, it comes up just fine. I was looking at vmstat, and it seems to tell me what I need. It's just that I need to present the data as simplistically as possible for the DBA's. Rainer This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: ZFS memory and swap usage
On Wed, 21 Mar 2007, Rainer Heilke wrote: [... reformatted ] We're running Update 3. Note that the DB _does_ come up, just not in the two minutes they were expecting. If they wait a few moments after their two-minute start-up attempt, it comes up just fine. So why don't you state the actual time it takes to come up? What is magic about 2 minutes? I was looking at vmstat, and it seems to tell me what I need. It's just that I need to present the data as simplistically as possible for the DBA's. Rainer Regards, Al Hopper Logical Approach Inc, Plano, TX. [EMAIL PROTECTED] Voice: 972.379.2133 Fax: 972.379.2134 Timezone: US CDT OpenSolaris.Org Community Advisory Board (CAB) Member - Apr 2005 OpenSolaris Governing Board (OGB) Member - Feb 2006 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Re: ZFS memory and swap usage
I currently run 6 Oracle 9i and 10g dbs using 8GB SGA apiece in containers on a v890 and find no difficulties starting Oracle (though we don't start all the dbs truly simultaneously). The ARC cache doesn't ramp up until a lot of IO has passed through after a reboot (typically a steady rise over 4-8 hours). I use the mdb -k method at startup before the containers come up and the zfs datasets are available, with mixed success in being able to hold down kernel arc memory over time but with a definite extension of free memory.. Setting ARC cache limits helps for awhile after a system has been up and is slowly gaining cache but, generally speaking, Oracle runs well even with a low free and high arc cache and that ARC does dump memory reasonably well (though with added overhead) in S10U3, allowing me to start a single instance of Oracle with an 8GB SGA on a machine showing only 4GB free (according to top). And then another. And then another. This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Re: ZFS memory and swap usage
Thanks. Like above, knowing the ARC takes time to ramp up strongly suggests that it won't be an issue on a normally booting system. It sounds like your needs are much greater, and that your databases are running fine. I can take this information to the DBA's and use it to manage their expectations. I think the hard part will be getting them to accept that the ARC will go down to accomodate Oracle's needs, but it may not go down fast enough to accomodate starting up a database five times larger than anything we would have on this server in under 120 seconds after the server has been runing for a few days/weeks. Thanks. :-) Rainer This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: ZFS memory and swap usage
Hello Rainer, Friday, March 16, 2007, 11:11:16 PM, you wrote: RH Thanks for the links, but this is not really the kind of data I'm RH looking for. These focus more on I/O. I need information on the RH memory cahing, and so on. Specifically, I need data that shows how RH starting up a 10GB SGA database on a 16GB machine will not be able RH to flush the ZFS cache as quickly as the DBA's are assuming, and RH how to point them to more realistic tests/metrics, and get them RH away from top's simplistic viewpoint of memory under S10. ZFS should give back memory used for cache to system if applications are demanding it. Right it should but sometimes it won't. However with databases there's simple workaround - as you know how much ram all databases will consume at least you can limit ZFS's arc cache to remaining free memory (and possibly reduce it even more byt 2-3x factor). For details on how to do it see 'C'mon ARC, stay small...' thread here. So if you have 16GB RAM in a system and want 10GB for SGA + another 2GB for Oracle + 1GB for other kernel resources you are with 3GB left. So I would limit arc c_max to 3GB or even to 1GB. -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Re: ZFS memory and swap usage
Overall ZFS/Database blogs: http://blogs.sun.com/realneel/entry/zfs_and_databases http://blogs.sun.com/roch/entry/zfs_and_oltp Memory: http://www.opensolaris.org/jive/thread.jspa?messageID=82353#82353 (There are more postings on ram.. just search the forum) This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
