slow IMAP data transfer

David Carter dpc22 at
Thu Feb 9 05:46:29 EST 2006

On Thu, 9 Feb 2006, Juris Orlovs wrote:

> Before that I was setting up Cyrus IMAP mail servers on Linux and there 
> was no such problems. Maybe it's OS issue? I also have set up such 
> system on Celeron 800MHz, 256MB RAM and 80GB SEAGATE (FreeBSD 4.11), the 
> results are aproximately the same. For SMTP i'm using Postfix, and it 
> also shows bad results on data transfer.

Cyrus and Postfix both make very heavy use of fsync() to flush data to 
disk before they confirm actions back to the sending system. RAID 
controllers or disk boxes with battery backed writeback cache help lots.

David Carter                             Email: David.Carter at
University Computing Service,            Phone: (01223) 334502
New Museums Site, Pembroke Street,       Fax:   (01223) 334679
Cambridge UK. CB2 3QH.

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