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I'm building a Centos 7 server to hold Postgres backups (using Barman). The Dell PowerEdge server has a Perc-8 controller (H710P), and there are 12each 3TB 7200rpm SAS drives available for a raid set to store the data. I'd use the Perc to do the Raid, but wondering what Raid level to choose. I hate to waste disk space on Raid-10, since backups aren't like live data, and the more capacity the better. But Raid-5 is history, I guess, so I'm thinking of Raid-6 as a compromise.

Advice on which Raid level to use would be appreciated. And is there any issue about putting all 12 disks in one set? Thanks...

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  • What do you mean by RAID-5 is history? Nov 30, 2016 at 2:09
  • Common myth that disks are so large nowadays, that a read error is basically guaranteed
    – Patrick
    Nov 30, 2016 at 3:23
  • RAID5 isn't "history", but I wouldn't really call it "safe" either. RAID6 wouldn't be a bad choice if it can keep up with the amount of data you need to write it in in X amount of time.
    – JimNim
    Nov 30, 2016 at 20:58

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If you're going to use a hardware card, RAID 50 or 60 seems fine for this case. 10 is overkill. For storing a backup of living data (rather than something like tapes), I generally prefer the use of ZFS or BTRFS to maintain the integrity of my dataset and to provide reasonably functional inline snapshots. That would preclude the use of a hardware RAID abstraction, and would instead involve using JBOD mode on your card and allowing the software to handle things instead. Even if you were doing this, I would still recommend a striped set of ZFS-Z2 sets.

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  • Unfortunately HBA mode is only available on PERC 9 cards and later... otherwise, this would be a solid option
    – JimNim
    Nov 30, 2016 at 20:59
  • That's really unfortunate, and has been a continual frustration of mine with PERCs.
    – Spooler
    Nov 30, 2016 at 21:41
  • A good alternative might be the LSI 9207-8i for internal drives. It's the same as the card used for HBA connections to external 6Gbps SAS JBODs for Dell systems, and we've seen it used for internal drives with some success.
    – JimNim
    Dec 1, 2016 at 22:43

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