On Wed, Mar 12, 2014 at 06:37:13AM -0500, Stan Hoeppner wrote: > On 3/10/2014 11:56 PM, Ray Van Dolson wrote: > > RHEL6.x + XFS that comes w/ Red Hat's scalable file system add on. We > > have two PowerVault MD3260e's each configured with a 30 disk RAID10 (15 > > RAID groups) exposed to our server. Segment size is 128K (in Dell's > > world I'm not sure if this means my stripe width is 128K*15?) > > 128KB must be the stripe unit. > > > Have set up a concatenated LVM volume on top of these two "virtual > > disks" (with lvcreate -i 2). > > This is because you created a 2 stripe array, not a concatenation. > > > By default LVM says it's used a stripe width of 64K. > > > > # lvs -o path,size,stripes,stripe_size > > Path LSize #Str Stripe > > /dev/agsfac_vg00/lv00 100.00t 2 64.00k > > from lvcreate(8) > > -i, --stripes Stripes > Gives the number of stripes... > > > Unsure if these defaults should be adjusted. > > > > I'm trying to figure out the appropriate sw/su values to use per: > > > > http://xfs.org/index.php/XFS_FAQ#Q:_How_to_calculate_the_correct_sunit.2Cswidth_values_for_optimal_performance > > > > Am considering either just going with defaults (XFS should pull from > > LVM I think) or doing something like sw=2,su=128K. However, maybe I > > should be doing sw=2,su=1920K? And perhaps my LVM stripe width should > > be adjusted? > > Why don't you first tell us what you want? You say at the top that you > created a concatenation, but at the bottom you say LVM stripe. So first > tell us which one you actually want, because the XFS alignment is > radically different for each. > > Then tell us why you must use LVM instead of md. md has fewer > problems/limitations for stripes and concat than LVM, and is much easier > to configure. Yes, misused the term concatenation. Striping is what I'm afer (want to use all of my LUNs equally). I don't know that I necessarily need to use LVM here. No need for snapshots, just after the best "performance" for multiple NAS sourced (via Samba) sequential write or read streams (but not read/write at the same time). My setup is as follows right now: MD3260_1 -> Disk Group 0 (RAID10 - 15 RG's, 128K segment size) -> 2 Virtual Disks (one per controller) MD3260_2 -> Disk Group 0 (RAID10 - 15 RG's, 128K segment size) -> 2 Virtual Disks (one per controller) So I see four equally sized LUNs on my RHEL box, each with one active path and one passive path (using Linux MPIO). I'll set up a striped md array across these four LUNs using a 128K chunk size. Things work pretty well with the xfs default, so may stick with that, but to try and get it as "right" as possible, I'm thinking I should be using a su=128k value, but am not sure on the sw value. It's either: - 4 (four LUNs as far as my OS is concerned) - 30 (15 RAID groups per MD3260) I'm thinking probably 4 is the right answer since the RAID groups on my PowerVaults are all abstracted. Ray _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
