[horde] Bottleneck ? CPU or HDisk IO or RAM

[Linux Advocate]

> > good questions rob, thanx for making things clear... my answers below...
> 
> >> 1) How many *concurrent* users?
> >
> > say 1000? or about 70% at any one time.
> 
> Is that a guess, or a figure arrived at in a meaningful manner?  If
> the reality is half that then you'll potentially spend far more than
> you need.

educated guess... its 1500 users actually but concurrently 1000 is reasonable.
 
> Are the emails largely static, or do you have a large volume of
> incoming and/or outgoing?  If it's largely static then caching will
> help massively, if it's largely dynamic then it won't help as much.

oh... havent thought abt this. i would say its a mixed environment.

> >> 2) What IMAP server?
> >
> > dovecot
> 
> Maildir or mbox?  Have you followed any of their published tuning
> advice (http://wiki.dovecot.org/PerformanceTuning)?  Have you
> consulted the dovecot mailing lists (particularly their archives) for
> advice on configuration and sizing?

maildir for sure.

> >> 3) What configuration of SATA drives?  A single 1 TB drive will be
> >> slower to read than a pair of 1 TB in a RAID0, which will be slower
> >> than 4 half TB drives in a RAID10.  Good quality (ie expensive) SATA
> >> RAID will be faster than cheap hardware RAID, and software RAID may be
> >> faster than cheap hardware RAID.
> >
> > say 6 x 750 GB Sata disks
> 
> Configured how - is that a 6 disk RAID5 array or a 6 disk RAID10 array
> (ie a stripe of 3 RAID1 pairs)?  Is it hanging off a hardware RAID
> controller (brand and model?) or as a software RAID?  What type of bus
> is it hanging off of if it's a controller (PCI, PCI-X, PCIe etc)?


perc raid controller, pci-e. a raid 5 config.


>                  Please keep list traffic on the list.
> 
> Rob MacGregor
>       Whoever fights monsters should see to it that in the process he
>         doesn't become a monster.                  Friedrich Nietzsche
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