[Kolab-devel] Cyrus Murder and kolab

[Martin Konold]

Am Montag, 16. Mai 2005 14:13 schrieb christophe robert:

Hi,

> Do you use an external card like "Umem (cache)" to improve the writing .
>
> Is it possible to use disks "10000 RPM"  without  having a bottleneck  
> (in Writing ) for this configuration

Use a decent RAID level like RAID 10 and don't worry about the write 
performance too much.

Most access is read not write and most important the write IO latency is 
easily hidden by the OS while reading typically means that the user process 
has to really wait until the data arrives.

According to my measurements having a HW write cache is a waste while having 
some hw cache in the raid controller for reading helps a little bit.

In generell giving the host machine enough memory helps most as access to main 
memory is about 1-2 orders faster than access to the cache memory on a PCI 
card.

Last but not least SCSI instead of ATA pays for a kolab server!

Regards,
-- martin

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