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Need RAID recommendations please

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6 replies

by smith_jacob

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I have two Dell 6800 that are clustered and attached to two powervault 220s. What is the recommended RAID config when implementing a DB. Space is not an issue, I am more concerned with redundancy and performance. Is it to have the RAID array span accross the 220's or have the RAID configured on each 220 seperately?

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by absolutely

RAID 0 means striping, and equates to performance at increased risk -- files are written in parts, to two drives, meaning that failure risk is doubled. Other RAID numbers employ parity or a mixture of "striping" and "mirroring" to achieve varying balances of performance advantage & redundancy.

by jdclyde

Of course you need multiple hard drives for this, minimum of three, I believe.

Raid 1 gives you mirroring for your reduncancy
Raid 0 gives you striping for performance
Raid 5 does both.

by cmiller5400

Three drives minimum for RAID5. One drive is used for the parity. the rest for storage. So total storage is (Number of Drives - 1) * (storage space) = Total Free Space. Use hardware RAID whenever possible.

EDIT: Gotta read more carefully the question... If you are using a DB, RAID5 is probably going to be the way to go. Just remember that writes on RAID5 take much longer (need to calculate the parity information) than reads... So if your database is VERY heavy on the writes, it may be better to do a little research on what the different levels of RAID can offer. I know I have seen articles on this before here on techrepublic.

by jdclyde

And with the speed of drives these days, I don't see a parity calculation being your bottleneck.

A note, if this is critical, you should have a spare HD sitting on a shelf. If one were to die, you don't have to wait half a day to get the system back up and running. A day of down time can easily cost more than the price of a HD sitting on a shelf.

by cg it

often overlooked when determining performance is memory. Each of those poweredge's can be dual processor Xeons and each will support 64 GB of DDR2 and 3 TB of storage on SCSI controller. When you add in the powervaults storage, with 4 TBs each per enclosure, lots of storage space. The poweredged's are SCSI RAID 0/1/5 and the powervaults have 0/1/5/10/50 RAID arrays.

I would say use RAID 10 on the powerfaults with hotswap SCSI and RAID 5 on the poweredges with hotswap SCSI.

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