It sounds like you’re suggesting RAID 5, no hot spare. And if you don’t need the extra capacity this layout implies, get an R6. If you don’t do those things you can still get bit in the ass with raid6 and a hot spare. But before all of that, make sure you’re doing regular scrubs on the array, use drives that have proper error timeouts so their errors are actually corrected during scrubs, have one or two same model drives on hand and properly replace them when the time comes. Before raid6+hotspare I’d consider raid15. It costs you both performance and capacity and isn’t worth it. If you’re going to forego regular backups and think raid6 bridge that gap, I think that’s a mistake.Īs for hot spare, forget it. In any case there should be sufficient regular backups that you shouldn’t need to depend on raid6. #Pegasus2 r6 drive not mounting isoISo I’m not sure what the extra drive redundancy gets you. Once even one disk has failed, the degraded mode performance I’m very skeptical will supply what you need to actively use the array while the rebuild is occurring. #Pegasus2 r6 drive not mounting plusThe raid6 RMW penalty is significantly worse than raid5, plus the hot spare means you’re at best 5x read speeds, which depending on the drives will vary alot unless they are short stroked. What’s this for? Video production work or as a backup? What drives? Alex Gerulaitis | Systems Engineer | DV411 – Los Angeles, CA If it’s uptime and data protection you’re looking for: RAID6 with a cold spare or two sitting on a shelf, and backups. Auto-rebuild in the middle of a project may not be a good idea. I also prefer to start and monitor a rebuild manually on smaller arrays with non-24/7 duty. Quite often the drive is actually healthy, just hiccupped, and can be marked as “online” w/o side effects. My personal preference in the event a drive is marked as failed on smaller arrays (less than 16 spindles) is to check that the drive indeed failed rather than just “marked as failed” because of a timeout. hot spares make more sense on larger arrays with RAID6. Hot spare means that (a) it’s just sitting there doing nothing until a drive fails, (b) your capacity, efficiency are down by 1/8th, something to consider given that RAID6 already takes away 2/8th of the capacity, (c) auto-rebuild that may bring performance down quite a bit, possibly for more than a day. Having a cold spare on a shelf is more efficient if you don’t run your array 24/7 and assuming you’ll know immediately that a drive failed.
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