4 ms·

Is QNAP doing something outside the ZFS spec here? If not, it's almost certain that solutions like TrueNAS can replicate this behaviour. If they are, I'd be con

Is QNAP doing something outside the ZFS spec here? If not, it's almost certain that solutions like TrueNAS can replicate this behaviour. If they are, I'd be concerned about vendor lock-in and data recovery. I'm assuming that QNAP are using ZFS, which a cursory search supports.

bhouston 5y ago
> I'm assuming that QNAP are using ZFS, which a cursory search supports. QNAP has two NAS OSes right now. The newer one is QuTS and it support ZFS. The other older one is QTS which doesn't use ZFS. Only the older QTS OS supports SSD Tiering. > Is QNAP doing something outside the ZFS spec here? If not, it's almost certain that solutions like TrueNAS can replicate this behaviour. If they are, I'd be concerned about vendor lock-in and data recovery. I am using TrueNAS for my ZFS solution and it doesn't offer anything out of the box to address the issues I am bringing up.
- lizknope 5y ago
  I don't use ZFS or QNAP but Linux has its own native dm-cache and bcache implementations for creating hybrid volumes out of SSD plus hard drives. I would suspect that QNAP is using one of them. https://en.wikipedia.org/wiki/Dm-cache https://en.wikipedia.org/wiki/Dm-cache https://en.wikipedia.org/wiki/Bcache https://en.wikipedia.org/wiki/Bcache
- tw04 5y ago
  TrueNAS very much supports a write log: https://www.truenas.com/docs/references/slog/ https://www.truenas.com/docs/references/slog/
  - bhouston 5y ago
    It is commonly misunderstood that ZIL SLOGs are write-back caches, they are not. They do not speed up large writes that do not fit into memory. I have tested this myself. You are spreading incorrect information, please stop. You know enough to be dangerous, but not enough to actually be right.
    - tw04 5y ago
      Says that guy that has three times now claimed I called SLOG a write-back cache and yet can't seem to find that quote anywhere. I'd appreciate if you stopped putting words in my mouth and stopped editing your posts to remove your false statements. You're acting like a child.
      - deleted 5y ago
        [deleted]

bhouston 5y ago

> I'm assuming that QNAP are using ZFS, which a cursory search supports. QNAP has two NAS OSes right now. The newer one is QuTS and it support ZFS. The other older one is QTS which doesn't use ZFS. Only the older QTS OS supports SSD Tiering. > Is QNAP doing something outside the ZFS spec here? If not, it's almost certain that solutions like TrueNAS can replicate this behaviour. If they are, I'd be concerned about vendor lock-in and data recovery. I am using TrueNAS for my ZFS solution and it doesn't offer anything out of the box to address the issues I am bringing up.

lizknope 5y ago
I don't use ZFS or QNAP but Linux has its own native dm-cache and bcache implementations for creating hybrid volumes out of SSD plus hard drives. I would suspect that QNAP is using one of them. https://en.wikipedia.org/wiki/Dm-cache https://en.wikipedia.org/wiki/Dm-cache https://en.wikipedia.org/wiki/Bcache https://en.wikipedia.org/wiki/Bcache
tw04 5y ago
TrueNAS very much supports a write log: https://www.truenas.com/docs/references/slog/ https://www.truenas.com/docs/references/slog/
- bhouston 5y ago
  It is commonly misunderstood that ZIL SLOGs are write-back caches, they are not. They do not speed up large writes that do not fit into memory. I have tested this myself. You are spreading incorrect information, please stop. You know enough to be dangerous, but not enough to actually be right.
  - tw04 5y ago
    Says that guy that has three times now claimed I called SLOG a write-back cache and yet can't seem to find that quote anywhere. I'd appreciate if you stopped putting words in my mouth and stopped editing your posts to remove your false statements. You're acting like a child.
    - deleted 5y ago
      [deleted]