On Nov 23, 2008 17:34 +0100, Jure Pečar wrote: > On Sun, 23 Nov 2008 07:06:28 -0800 (PST) > KenShelby <kshelby@xxxxxxxxxxxxx> wrote: > > I'm not looking for a single "magic bullet" answer. Are there any > > guidelines at all, any best practices that have been found over time to > > be a good place to start? What I seek is either informed opinion or > > information - if it exists - about how to make choices on EXT3 journal > > configuration for a SAN installation. > > Common sense and knowlege of your application are a good start. > > You said that you have lots of random io, so I would be more concerned over > latency than bandwith. If your SAN provides you with good enough latency > then I wouldn't bother much about journal configs and go with defaults, but > if your SAN sits on something like iSCSI with noticeable latency then I'd > test a setup with journal on local disk, possibly even in full data > journaling mode. If I had the money I'd look into SSDs for that purpose, > either in form of SSD sata/sas drive or in form of PCIe card (fusion-io for > example). One important consideration is if you have hardware RAID-5/6, then it is a bad idea to put the journal on the same device as the filesystem. That causes a lot of read-modify-write of RAID stripes, and bad performance. Much better to put the journal on a RAID-1 device. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
