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Re: RAID card recommendation

From: Richard Neill <rn214(at)cam(dot)ac(dot)uk>
To:
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: RAID card recommendation
Date: 2009-11-24 17:39:27
Message-ID: 4B0C1A4F.9000903@cam.ac.uk (view raw or flat)
Thread:
Lists: pgsql-performance
Matthew Wakeling wrote:
> 
> We're about to purchase a new server to store some of our old databases, 
> and I was wondering if someone could advise me on a RAID card. We want 
> to make a 6-drive SATA RAID array out of 2TB drives, and it will be RAID 
> 5 or 6 because there will be zero write traffic. The priority is 
> stuffing as much storage into a small 2U rack as possible, with 
> performance less important. We will be running Debian Linux.
> 
> People have mentioned Areca as making good RAID controllers. We're 
> looking at the "Areca ARC-1220 PCI-Express x8 SATA II" as a possibility. 
> Does anyone have an opinion on whether it is a turkey or a star?
> 
> Another possibility is a 3-ware card of some description.
> 

Do you actually need a RAID card at all? It's just another point of 
failure: the Linux software raid (mdadm) is pretty good.

Also, be very wary of RAID5 for an array that size. It is highly 
probable that, if one disk has failed, then during the recovery process, 
you may lose a second disk. The unrecoverable error rate on standard 
disks is about 1 in 10^14 bits; your disk array is 10^11 bits in size...

We got bitten by this....

Richard


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