Im looking to configure a new sql server with a dell r730xd 24 bay chassis and need some help with choosing the drive configuration for sql server. Need help on what to choose for our RAID configuration on the data and log drives. What will we get the best overall performance out of the machine.

Currently we have 2 databases, and would like to separate them onto their own sets of drives (data and log) to a total of 4 drive letters. They are 600gb and 500gb on the data side. Currently they are both around 20gb log files. We would like to get to 1.8tb total space for the data drives and 600gb for the log files.

We have a choice of RAID 5 with 15K drives or RAID 10 with 10K drives. the 15K drives come in 300gb and 600gb. The 10K drives come in 300gb, 600gb, 1.2tb and 1.8tb. What would be optimal for performance?

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    If you want overall performance, Raid10. If you're mostly reads (90%+) Raid5 is also fine. If your database is write heavy (50+%) Raid10. – Sean Gallardy Aug 15 '16 at 15:54
  • What Sean said. Logs are massively write heavy so RAID 10 makes more sense for that. GENERALLY writing to disk can be controlled well but your patterns might not match, so RAID 5 or even 6 is typically fine. Are you using SSDs? – Ali Razeghi Aug 15 '16 at 16:19
  • No we are not using ssd's we have the option of 10k or 15k Sas drives. i dont know if 10k in raid 10 would beat out 15k drives in raid 5? – Jim Aug 15 '16 at 17:13
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    Depends on the activity. A write to raid 5 takes 4 IOs (from the drive's perspective) whereas raid 10 only takes 2. Like I said, if you're write heavy, the small amount of IOPs gained from 15k vs 10k is trivial. Also, it's the same disks why can't they be 15k and used for raid 10? – Sean Gallardy Aug 16 '16 at 1:29
  • Thanks for your advice, I ran a bunch of querys and we are very write heavy and have decided to go with RAID 10 with 15k drives. – Jim Aug 16 '16 at 15:32

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