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I kept my article neutral and I realise I should have stated that I consider Linux software RAID and ZFS in the same boat in terms of perceptions about RAID. P

I kept my article neutral and I realise I should have stated that I consider Linux software RAID and ZFS in the same boat in terms of perceptions about RAID. People forgo on both Linux software RAID and ZFS because of scary stories. ZFS is an interesting alternative to Linux software RAID that discussion is a different topic all together.

garmaine 6y ago
The two fundamentally are different in ways that you are conflating. A hardware raid card will eject a disk that shows a single URE. Your zfs volume will happily correct the error and just report it as a minor statistic that is cleared on your next reboot. Yes zfs is immune to the problem the zdnet article hyped up. Because it is immune by design in a way that is purposefully different from raid.
- StillBored 6y ago
  That completely depends on the RAID controller/software. Smarter ones, with sufficient slots will leave the "failing" drive online long enough to assure that should a sector fail to be read from the remaining drives an attempt can be made to read it from the "Bad" drive as well. In cases where the drive is being kicked for excessive SMART relocation, or hard read errors this could be the diff between the array going offline and the rebuild succeeding. For something like mdadm, you can simulate this by upgrading /reshaping from RAID5 to RAID6 (or similar) and then pulling the failing drive and reshaping back to raid5. Or as did a few times a decade+ ago when we had a really bad batch of drives, pick the bad sector off the failed drive, compute the corrected sector "by hand" and write it back to the drive with a read error.
layoutIfNeeded 6y ago
Scary stories of ZFS? I thought it was the pinnacle of file systems in terms of reliability.
- magicalhippo 6y ago
  I mean there are some people who have lost ZFS pools or a lot of data. But for each one of those, there are tons more that have lost entire hardware RAIDs. There's also tons more of those that had some horrible error and imagined their ZFS pool was gone for sure, only to find they just lost a couple of files, if anything at all.
- deelowe 6y ago
  The only issues I've had are with fragmentation and worrying about losing a disk during rebuilds.
- dehrmann 6y ago
  I think this has been fixed, but at one point, I used a log device with a one-time encryption key, thinking I didn't care that much about the data if there's a power loss. For the most part, ZFS didn't care either, but what it did care about was not mounting a pool with a missing disk. I had to edit metadata on the pool so it would mount with a different log device. Tools for this didn't exist--I was reading specs and source code, learning how ZFS know which devices belong in a pool.

garmaine 6y ago

The two fundamentally are different in ways that you are conflating. A hardware raid card will eject a disk that shows a single URE. Your zfs volume will happily correct the error and just report it as a minor statistic that is cleared on your next reboot. Yes zfs is immune to the problem the zdnet article hyped up. Because it is immune by design in a way that is purposefully different from raid.

StillBored 6y ago
That completely depends on the RAID controller/software. Smarter ones, with sufficient slots will leave the "failing" drive online long enough to assure that should a sector fail to be read from the remaining drives an attempt can be made to read it from the "Bad" drive as well. In cases where the drive is being kicked for excessive SMART relocation, or hard read errors this could be the diff between the array going offline and the rebuild succeeding. For something like mdadm, you can simulate this by upgrading /reshaping from RAID5 to RAID6 (or similar) and then pulling the failing drive and reshaping back to raid5. Or as did a few times a decade+ ago when we had a really bad batch of drives, pick the bad sector off the failed drive, compute the corrected sector "by hand" and write it back to the drive with a read error.

layoutIfNeeded 6y ago

Scary stories of ZFS? I thought it was the pinnacle of file systems in terms of reliability.

magicalhippo 6y ago
I mean there are some people who have lost ZFS pools or a lot of data. But for each one of those, there are tons more that have lost entire hardware RAIDs. There's also tons more of those that had some horrible error and imagined their ZFS pool was gone for sure, only to find they just lost a couple of files, if anything at all.
deelowe 6y ago
The only issues I've had are with fragmentation and worrying about losing a disk during rebuilds.
dehrmann 6y ago
I think this has been fixed, but at one point, I used a log device with a one-time encryption key, thinking I didn't care that much about the data if there's a power loss. For the most part, ZFS didn't care either, but what it did care about was not mounting a pool with a missing disk. I had to edit metadata on the pool so it would mount with a different log device. Tools for this didn't exist--I was reading specs and source code, learning how ZFS know which devices belong in a pool.