10 Replies to “RAID cards for DragonFly”

  1. Hardware RAID is so 90ies. I really like ZFS in this regard… Just throw a second disk at it and your pool is mirrored (it’s smart enough to only mirror the disk sectors which are actually in use).

    I wish HAMMER could do that, too.

  2. Software RAID has always made me nervous. ZFS mirroring is nice, but it’s still software RAID and I’m still reflexively distrustful.

  3. Justin

    Why does software raid scare you?

    We don’t hardcode into hardware web servers. We don’t hardcode into hardware databases.

    Why does having a software based raid solution scare you?

    The whole point to writing something in software is for easy of development and maintenance.

    That’s why operating systems exist in the first place. So that you don’t have to do everything in hardware but instead in software.

  4. There’s been plenty of software RAID solutions over the years, especially when hard drives and RAID hardware were relatively more expensive. Since they were software, they were writing data over multiple drives. If something happened to a disk in a 2-disk volume, the volume would be broken, and there was no way to access the data on the remaining disk. This is more of a problem for people that confuse redundancy with backup.

    Worse were the RAID devices that companies like Dell would supply, that weren’t actually RAID, but required software drivers to work – and only worked under Windows. I hated that. Maybe you’re too young to have encountered that sort of thing, in which case you are lucky.

  5. @justin

    So what’s your specific concern about zfs software raid capabilities?

  6. Justin

    You said “ZFS mirroring is nice, but it’s still software RAID and I’m still reflexively distrustful.”

    Then when asked what’s your concern about zfs, you say you “don’t have one”

    Are you just trolling or what?

    So what’s wrong with zfs software based raid?

  7. Also there’s self-healing with ZFS. When a block checksum doesn’t match and there’s redundancy, the known-good version is used and the bad one is replaced.

    HAMMER has checksums but it’s lacking self-healing… You can’t do that with Hardware RAID as well.

  8. All RAID is software RAID. I trust ZFS more than I trust the RAID drive software.

  9. And if hardware raid fails, you have to replace the hardware raid with the exact same model number. That’s not easy when sometimes exact specific hardware raid is readily available.

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