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Re: [Xen-users] Re: Re: Redundant server setup

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Re: Re: Redundant server setup
From: Javier Guerra <javier@xxxxxxxxxxx>
Date: Tue, 23 May 2006 16:24:23 -0500
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On Tuesday 23 May 2006 4:00 pm, Sylvain Coutant wrote:
> > 7-disk RAID5
>
> Are you serious ? Do you know the performance you can hope from this for
> write operations ?

sure, this part of the setup is actually running, and with very good results.  
it helps a lot that most files are 80-400GB, making almost all writes bigger 
than one stripe-row.  in those circumstances there's no need to read before 
writing.

with smaller files i'd be very carefull of the stripe size, but even 128Kb 
(default for most) x 6 = 768Kb, still far smaller than any significant file, 
and even less than the usual 4MB LVM blocksize

> Unless you don't have more than one write op for 1 000 000 reads, forget
> it.

i think i get even more writes than reads for each file

-- 
Javier

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