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This is a perpetuated myth that is patently false: ZFS loves cheap disks was the maxim when ZFS first came out, and with block checksums, explicit flush request

This is a perpetuated myth that is patently false: ZFS loves cheap disks was the maxim when ZFS first came out, and with block checksums, explicit flush requests directly to the drive electronics, a setting for keeping redundant file copies on a single disk and self-healing during a resilver, it couldn't be more wrong. ZFS the is ideal filesystem for desktops and laptops running the cheapest, shittiest consumer grade drives. It is the only filesystem / volume manager capable of guaranteeing data integrity on such shitty, unreliable drives like consumer grade drives are.

ghaff 8y ago
What myth? I wrote "a lot of its capabilities are much more relevant for large servers" Which is true. Very large scale, integrated volume management, tiered storage, etc. There are a lot of features on ZFS that either aren't relevant at all or are relevant to a vanishingly small percentage of MacOS users. You're right that ZFS has some nice data integrity features. Apple apparently didn't think those were a sufficiently big deal as a practical matter to offset the other issues.
- Annatar 8y ago
  "I wrote "a lot of its capabilities are much more relevant for large servers" Which is true." That is a myth. It's simply not the case. What you could argue is that if you solve a problem for servers, it is also solved for consumer grade hardware, but writing a volume manager / filesystem for servers is empathically not what Bill Moore and Jeff Bonwick set out to do. Jeff wanted to solve the problem of data integrity in a filesystem (his own words), not explicitly design a solution relevant for servers. ZFS is perfect for laptops and desktops. See also https://wiki.illumos.org/download/attachments/1146951/zfs_last.pdf https://wiki.illumos.org/download/attachments/1146951/zfs_la... ...if you still have difficulty with the concept of ZFS being perfect for shitty consumer grade drives in desktops and laptops, do this mental exercise: which features of ZFS would make it not be a good fit for a cheap consumer drive?
- detaro 8y ago
  Tiered storage appears to be relevant for desktop systems given the number of "SSD-cache for your harddrives" solutions around (although maybe not for Macs, given their hardware limitations, on the other hand nothing strictly prevents using something like that with external disks). Snapshots are quite powerful for backup/recovery features.
icefo 8y ago
As long as you disable the disk write cache. I had a home Nas running zfs on a unreliable power supply and I lost the contents of the Nas a few times before I disabled the write cache. Ext4 seems to tolerate this much better.
- m45t3r 8y ago
  > As long as you disable the disk write cache. > I had a home Nas running zfs on a unreliable power supply and I lost the contents of the Nas a few times before I disabled the write cache. Ext4 seems to tolerate this much better. Maybe it is because Ext4 by default "bypass"[1] write caches by default. [1]: Look at barriers in Ext4 documentation: http://man7.org/linux/man-pages/man5/ext4.5.html http://man7.org/linux/man-pages/man5/ext4.5.html
  - icefo 8y ago
    Thank you. I wondered why ext4 tolerate sudden power loss much better.
    - Annatar 8y ago
      It doesn't tolerate power loss at all; it doesn't have any kind of facilities to do that, and write barriers will only work if the underlying storage supports it, otherwise ext4 will revert to no write barriers, so it's spotty at best, hit-and-miss. There is no way to detect silent data corruption on any generation of an ext filesystem and if you lose power, you've not only lost data but it has most likely been silently corrupted as well. ext filesystems will be none the wiser to this. Same with XFS, UFS, or any other classic filesystem, but ext family of filesystems is particularly shoddy in that regard.
- Annatar 8y ago
  Write cache should always be disabled, even if one is running multimillion dollar storage arrays, no ifs, buts, or maybes. That goes without saying, it's the holy law of data integrity to any storage architect who understands the intricacies of storage systems. However, it has nothing to do with ZFS per se.
fierarul 8y ago
> ZFS loves cheap disks was the maxim when ZFS first came out This is the first time I've heard this expression. So, you're telling me I shouldn't have bought all those WD Red drives for my ZFS machine?
- Annatar 8y ago
  "This is the first time I've heard this expression." Slide 18, "ZFS loves cheap disks", underlined. https://wiki.illumos.org/download/attachments/1146951/zfs_last.pdf https://wiki.illumos.org/download/attachments/1146951/zfs_la... I've been running ZFS in production and at home since July of 2006. Just resilvered a bad consumer drive with two bad blocks. All fixed now.
  - fierarul 8y ago
    > Just resilvered a bad consumer drive with two bad blocks. All fixed now. Hm, just makes one put ZFS everywhere! > The better the drives, the better the performance and data integrity with ZFS, but WD is really consumer grade hardware: Seagate ES or Hitachi enterprise drives have completely different firmware. Is the firmware the one that really matters here or is it about the quality of the hardware itself?
    - Annatar 8y ago
      The mechanical internals between a consumer grade and an enterprise drive from the same manufacturer are usually identical and might only differ in things like read and write cache sizes. Firmware is the only thing that matters, especially since that is the #1 source of the problems.
- Annatar 8y ago
  The better the drives, the better the performance and data integrity with ZFS, but WD is really consumer grade hardware: Seagate ES or Hitachi enterprise drives have completely different firmware.

ghaff 8y ago

What myth? I wrote "a lot of its capabilities are much more relevant for large servers" Which is true. Very large scale, integrated volume management, tiered storage, etc. There are a lot of features on ZFS that either aren't relevant at all or are relevant to a vanishingly small percentage of MacOS users. You're right that ZFS has some nice data integrity features. Apple apparently didn't think those were a sufficiently big deal as a practical matter to offset the other issues.

Annatar 8y ago
"I wrote "a lot of its capabilities are much more relevant for large servers" Which is true." That is a myth. It's simply not the case. What you could argue is that if you solve a problem for servers, it is also solved for consumer grade hardware, but writing a volume manager / filesystem for servers is empathically not what Bill Moore and Jeff Bonwick set out to do. Jeff wanted to solve the problem of data integrity in a filesystem (his own words), not explicitly design a solution relevant for servers. ZFS is perfect for laptops and desktops. See also https://wiki.illumos.org/download/attachments/1146951/zfs_last.pdf https://wiki.illumos.org/download/attachments/1146951/zfs_la... ...if you still have difficulty with the concept of ZFS being perfect for shitty consumer grade drives in desktops and laptops, do this mental exercise: which features of ZFS would make it not be a good fit for a cheap consumer drive?
detaro 8y ago
Tiered storage appears to be relevant for desktop systems given the number of "SSD-cache for your harddrives" solutions around (although maybe not for Macs, given their hardware limitations, on the other hand nothing strictly prevents using something like that with external disks). Snapshots are quite powerful for backup/recovery features.

icefo 8y ago

As long as you disable the disk write cache. I had a home Nas running zfs on a unreliable power supply and I lost the contents of the Nas a few times before I disabled the write cache. Ext4 seems to tolerate this much better.

m45t3r 8y ago
> As long as you disable the disk write cache. > I had a home Nas running zfs on a unreliable power supply and I lost the contents of the Nas a few times before I disabled the write cache. Ext4 seems to tolerate this much better. Maybe it is because Ext4 by default "bypass"[1] write caches by default. [1]: Look at barriers in Ext4 documentation: http://man7.org/linux/man-pages/man5/ext4.5.html http://man7.org/linux/man-pages/man5/ext4.5.html
- icefo 8y ago
  Thank you. I wondered why ext4 tolerate sudden power loss much better.
  - Annatar 8y ago
    It doesn't tolerate power loss at all; it doesn't have any kind of facilities to do that, and write barriers will only work if the underlying storage supports it, otherwise ext4 will revert to no write barriers, so it's spotty at best, hit-and-miss. There is no way to detect silent data corruption on any generation of an ext filesystem and if you lose power, you've not only lost data but it has most likely been silently corrupted as well. ext filesystems will be none the wiser to this. Same with XFS, UFS, or any other classic filesystem, but ext family of filesystems is particularly shoddy in that regard.
Annatar 8y ago
Write cache should always be disabled, even if one is running multimillion dollar storage arrays, no ifs, buts, or maybes. That goes without saying, it's the holy law of data integrity to any storage architect who understands the intricacies of storage systems. However, it has nothing to do with ZFS per se.

fierarul 8y ago

> ZFS loves cheap disks was the maxim when ZFS first came out This is the first time I've heard this expression. So, you're telling me I shouldn't have bought all those WD Red drives for my ZFS machine?

Annatar 8y ago
"This is the first time I've heard this expression." Slide 18, "ZFS loves cheap disks", underlined. https://wiki.illumos.org/download/attachments/1146951/zfs_last.pdf https://wiki.illumos.org/download/attachments/1146951/zfs_la... I've been running ZFS in production and at home since July of 2006. Just resilvered a bad consumer drive with two bad blocks. All fixed now.
- fierarul 8y ago
  > Just resilvered a bad consumer drive with two bad blocks. All fixed now. Hm, just makes one put ZFS everywhere! > The better the drives, the better the performance and data integrity with ZFS, but WD is really consumer grade hardware: Seagate ES or Hitachi enterprise drives have completely different firmware. Is the firmware the one that really matters here or is it about the quality of the hardware itself?
  - Annatar 8y ago
    The mechanical internals between a consumer grade and an enterprise drive from the same manufacturer are usually identical and might only differ in things like read and write cache sizes. Firmware is the only thing that matters, especially since that is the #1 source of the problems.
Annatar 8y ago
The better the drives, the better the performance and data integrity with ZFS, but WD is really consumer grade hardware: Seagate ES or Hitachi enterprise drives have completely different firmware.