Gurgel, Flavio escribió:
----- "Richard Neill" <rn214@xxxxxxxxx> escreveu:
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
Linux kernel software RAID is fully supported in Debian Lenny, is quite cheap to implement and powerful.
I would avoid SATA disks but it's just me. SAS controllers and disks are expensive but worth every penny spent on them.
Prefer RAID 1+0 over RAID 5 not only because of the risk of failure of a second disk, but I have 3 cases of performance issues caused by RAID 5.
It's said that performance is not the problem but think twice because a good application tends to scale fast to several users.
Of course, keep a good continuous backup strategy of your databases and don't trust just the mirroring of disks in a RAID fashion.
Flavio Henrique A. Gurgel
Consultor -- 4Linux
tel. 55-11-2125.4765
fax. 55-11-2125.4777
www.4linux.com.br
Do you expose that performance issued caused by RAID 5? Because this is
one of our solutions here on my country to save the data of our
PostgreSQL database. Which model do you recommend ? RAID 0,RAID 1, RAID
5 or RAID 10?
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