Subject: Re: RaidFrame poor performance
To: Mihai CHELARU <>
From: Christian Smith <>
List: current-users
Date: 01/19/2005 15:52:27
On Wed, 19 Jan 2005, Mihai CHELARU wrote:

>Daniel Carosone wrote:
>> Therefore, for almost every write you do, you wind up doing a
>> read-modify-write cycle; that's what kills your performance.
>Just wondering: would vinum work better ?
>> If you have the chance, for the sake of demonstration, compare
>> performance with 3-way and 4-way raid-0.
>What I have: 2 IDE controllers on motherboard and 4 HDDs.

If the disks don't support disconnects (which I believe will be the case)
you'll also have the problem that access to two disks on the same ATA
channel will be serialized, thus accesses with big seeks will make you
incure the latency of 2 seeks one after the other, instead of

Buy another controller, and give each disk it's own channel.

>What I need: striping with failover without wasting resources so
>striping and mirroring is out of the question as I'll waste 120GB.

Configure the disks into a 3 way RAID-5, and keep the remaining disk as a
hot spare. You'll still 'waste' a disk, but it'll pay dividends when a
disk dies and you will still have full redundency when the spare disk is
brought online.



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