Ever growing mailboxes and archiving

Pascal Gienger Pascal.Gienger at uni-konstanz.de
Wed Apr 20 12:07:31 EDT 2011

Vincent Fox <vbfox at ucdavis.edu> wrote:

> On 4/20/2011 12:50 AM, Rudy Gevaert wrote:
>> Hi Vincent,
>> How do you make the snapshot consistent (netbackup+vmware snapshot)?
>> Do you stop cyrus?
> I'll have to ask our backup admin if you want technical specifics
> and guarantees, but my understanding was that the process included
> an atomic snapshot of the VM.  Then the backup is made of that.
> We don't stop anything it's done hot.
> As I said, we are not presently running Cyrus in a VM,

Just a little side mark: As my memory serves me right, you seem to be 
running Cyrus in a Solaris environment using the ZFS file system.

Do you want to stop using it?

Solaris in VMWARE never performed really well, and seemless migration from 
one vmware node to another is also not possible without proper vmware tools.
My tests with Solaris in a VM environment (other than Sun xVM/Xen) were 
horrible - ZFS' performance went down due to noticeable delays due to the 
"too many caches between"-error.

The Cyrus mail store is one of the left servers not being migrated to our 
VM infrastructure due to ZFS. We are upgrading hardware to have 64 GB of 
RAM on our Cyrus store because ARC cache is like having plain gold for 
performance. I am left to have own "iron". :)

Backups are done via ZFS snapshots.

All VM backup systems being able to do "live snapshots and backups" are 
based on the fact that they know the on-disk-structure of the filesystem 
the virtual disk is formatted with. ZFS is a no go in all these setups. 
Other systems rely on the information which blocks changed - this setup 
together with "thin provisioning" is useless with ZFS because due to the 
ZIL sequential writes/copy on write the "thin provisioning" will result in 
a "all blocks used"-disk after doing X TB of writes on a X TB disk volume 
- even if it is on the same file overwritten again and again.

And transferring our Cyrus Store to something other than ZFS is just out of 
reach. We have 50,000,000 files on the store in 102,000 mailboxes. No 
problem for ZFS, enough RAM for ARC (and/or good SSD for L2ARC!) provided.

I would be very lucky to know other peoples experiences with Cyrus in 
virtualized environments.

Solaris works well with Sun xVM, sure - but since Oracle has bought Sun, I 
don't have any possibility left to get actual copies of it so I deleted 
quite all installation of it.

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