Cyrus-imapd memory tuning

Bron Gondwana brong at
Mon Mar 10 08:29:22 EDT 2014

On Mon, Mar 10, 2014, at 07:49 PM, Marco wrote:
> With 8GB RAM,

I would recommend you increase that... even before you swap, you'll be seeing a drop in performance as hot files (indexes, mailboxes.db) get evicted from cache.  Memory is relatively cheap these days.

I realise you may be constrained by budget though.  Just to give you some details of what we use at FastMail...

I've nearly decommissioned our last IMAP server with only 32Gb RAM - the smaller ones have 48Gb now, and the big ones 92Gb.

As an interesting datapoint, the big ones cost about US$20k fully stocked, including 40Tb of RAID6 storage for email, plus 6Tb of RAID1 for search indexes and 800Gb of RAID1 SSD for hot metadata.  Based on these cases:

With 2Tb WD RE4 hard disks, 400Gb Intel DC 3700 SSDs, 92Gb RAM and a couple of pretty average Xeon processors.

Our previous build was a 2U box with 12 x 2Tb drives in the front and a pair of SSDs inside.  That only gives 15 Tb of usable RAID6 storage after OS and search is configured though.  They're about US $9k now, so slightly worse value than the big ones per unit storage.


  Bron Gondwana
  brong at

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