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Is RAID still needed?
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this post was submitted on 05 Apr 2024
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Asklemmy
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I'd say "old" RAID could be dead if you have proper backups and have the ability to replace a defect drive fast in the case uptime is crucial. But there's also modern RAID like btrfs and zfs that also can repair corrupted filed, caused by bitrot for example. Old RAID can't do that also hardware based RAID couldn't either when I used it until years ago. Maybe that changed but I don't see the point of hardware based RAID in most cases anymore
Hardware raid can 100% do any of the above tasks, and has always been able to do them. You need an actual raid card, not some half assed baked in mobo raid.
Hardware RAID was doing all of the above before software RAID was available to end users.
I wonder how to detect real raid card from simple switch? I guess to look at price and it should be really high?
Most discrete raid cards will do the job, but look for on card caching and a battery for "quality."
But AFAIK real RAID don't perform CRC, thy rely on drive to report bad sector. In case if on one drive data got corrupted, it would return data from one drive or another. In case of mirroring. If we aren't talking about RAID 6 I think.
RAID and backups serve different purposes. Backups are to prevent data loss, RAID is to prevent downtime in case of hardware failure. They are not interchangeable.
Different purposes true, but not exclusively. RAID only has effect on drive failure specifically. If downtime is intolerable then it's not the right solution to just use RAID and you should look into total redundancy of the hardware and more. It also comes with performance bottlenecks or improvements depending on the setup, that's another factor to take into account. So in the end it really depends on your requirements and backups can actually serve as an alternative, depending on your setup and as long as it meets your RTO
AFAIK only officially supported RAID modes in BTRFS are RAID0 and RAID1.
RAID56 is officially considered unstable.
Raid56 is a risky one in more filesystem than just btrfd though, but if you have a ups as backup, you should be fine.
UPS won't protect from Kernel Panic, sadly
True
What about dm-raid? Is it still risky? I guess so, because it's separate devices. So any software raid with 5-6 would be problematic?