On 5/3/2013 9:21 AM, Charles Marcus wrote:
On 2013-05-03 8:34 AM, Stan Hoeppner stan@hardwarefreak.com wrote:
I assume /var will hold user mail dirs.
Yes, in /var/vmail
Do /var/ and /snaps reside on the same RAID array, physical disks?
Yes - vmware host is a Dell R515, with ESXi installed to mirrored internal SATA drives, with 8 drives in RAID 10 for all of the VMs. All storage is this local storage (no SAN/NAS).
Your RAID10 is on a PERC correct? You have four 7.2K SATA stripe spindles. Do you mind posting the RAID10 strip/chunk size? The RAID geometry can be critical, not just for mail, but your entire VM setup. Also, what's your mdbox max file size?
How about the other filesystems I snipped? If you have a large number of filesystems atop the same RAID, some of them being XFS, this could create a head thrashing problem under high load increasing latency and thus response times.
Ouch...
Don't fret yet.
This ESXi host also hosts 2 server 2008R2 vms...
So, what, 3 production VMs total? That shouldn't be a problem, unless... (read below)
Would you mind posting: ~$ xfs_info /dev/vg/var
meta-data=/dev/mapper/vg-var isize=256 agcount=4, agsize=45875200 ... meta-data=/dev/mapper/vg-snaps isize=256 agcount=4, agsize=262144 blks
Ok, good, mkfs gave you 4 AGs per filesystem, 8 between the two. This shouldn't be a problem.
However, ISTR you mentioning that your users transfer multi-GB files, up to 50GB, on a somewhat regular basis, to/from the file server over GbE at ~80-100MB/s. If these big copies hit the same 4 RAID10 spindles it may tend to decrease IMAP response times due to seek contention. This has nothing to do with XFS. It's the nature of shared storage.
Thanks again Stan...
You bet.
-- Stan