On 02/28/2010 09:41 AM, Eric Shubert wrote:
Jake Vickers wrote:
On 2/27/2010 9:34 PM, MagicWISP Sales wrote:
Jake,
You are probably right, but we are a small ISP, and never will have
a large
mail server. If this server ever reaches 500 accounts I will be way
more
than shocked. So this works well for us. The really nice thing is
restoral
- it's a snap. If I have a few thousand email accounts, it would be a
different story.
;) I do not consider 500 users large, but that does seem to be the
break point for virtual environments that I've seen to date.
I'd be curious about these installations.
.) is pop vs imap a factor?
.) courier or dovecot?
.) which VM host/version?
.) paravirtual HW?
.) I/O scheduling methods? (host and guest)
.) VM guests on separate HDs or partitions?
Of course, it's also important to know what (if any) tuning has
already been done.
BL, where/what is the bottleneck??
'Course it's hard to test anything, since I don't have 500 users
laying around that are willing to let me mess with their email....
That's a stumbling block all right. ;)
I'd have to pull notes on the other systems - ESX 4 is the only one I
have committed to memory.
200 users or so, all running IMAP. Courier (since it is the official
package of QMT at this time - Dovecot to follow in the future).
Issue was mainly some users getting timeouts on IMAP connects and
accesses. No definitive pattern to it. One mailbox had 4M of mail,
another had 3G of mail in folders. Both experienced the same type issue,
and not consistently.
I do not have any details about the host environment. I was not even
told it was a VM environment until I got to poking around trying to find
out why the issue was happening. Originally were mapped to a NFS share
that was a RAID5 volume, and later moved to a direct attached storage
disk. Moving from NFS/RAID to DAS reduced the issues by 200% or so, but
still had 2-3 issues at peak times. No idea on other guests on the system.
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