Re: raid recomendation

On Thu, Dec 6, 2012 at 2:18 PM, Roberto Scattini <roberto.scattini@gmail.com> wrote:

hi, i have a new dell r720 server with 5 600gb disks.
his function will be a postgresql server (the size of the databases is really small with 600gb we should be fine for a long time).

which raid configuration would you recommend?

i was thinking in raid 5 with all five disks but i am not a expert.

Hi Roberto,

A RAID 5 volume including the 5 drives should work fine for you. A question you should consider when you are taking this decision is: how fast can you replace a failed drive? You must know that in the meanwhile you'd be vulnerable, since an additional failure could lead to data loss. If you can't exchange the drive fast enough, maybe you should use an spare drive or thinking about RAID 6 (I've never used it though).

i prefer redundandcy against size (i mean, i can sacrifice space). and i dont want performance degradation for doing raid with an incorrect number of disks.

Another think you could consider is creating a separate volume for the OS. Particularly, I'd go for a 2 disks RAID 1 for the OS and a 3 disks RAID 5 for the database, since capacity isn't a problem. This configuration ensures that the database I/O traffic does not competes with the OS (when swapping and stuff). But that also depends on your hardware configuration.

Best,

thanks in advance!

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Roberto Scattini

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Pedro Eugênio Rocha