[kwlug-disc] Filesystems for backups

[Paul Nijjar]

On Wed, Aug 07, 2019 at 08:39:48PM -0400, Mikalai Birukou via kwlug-disc wrote:
> 
> >On 2019-08-07 5:49 p.m., Paul Nijjar via kwlug-disc wrote:
> >>ZFS with FreeNAS or Ubuntu (using ZFS on Linux), raidz
> >>------------------------------------------------------
> 
> I want to provide further illustration. Here, https://stackoverflow.com/questions/44375657/how-to-remove-a-device-disk-from-zpool-where-there-is-no-redundancy
> , there is a listing of someone's pool


Right. My understanding is that if I have a bunch of single-disk vdevs
(daX in the example below) then I can make a pool out of them. Then
they become striped? So this is similar to RAID0. Then what happens
when a drive dies?

As for removing a vdev, I thought the mechanism is that ZFS writes an
indirection layer to other disks. If the disk I am removing is full of
data, then this is costly. 

http://blog.moellenkamp.org/archives/50-How-to-remove-a-top-level-vdev-from-a-ZFS-pool.html

- Paul



> 
> ```
> 
> |NAME STATE READ WRITE CKSUM pdx-zfs-02 DEGRADED 0 0 0 raidz2-0 DEGRADED 0 0
> 0 gptid/c459110a-a73c-1a49-b12c-f03fbec6eca6 FAULTED 158 25.3K 0 too many
> errors gptid/8c87e988-7832-1e44-9c45-abe95ee2d8f7 ONLINE 0 0 0
> gptid/3b4be4d0-136e-41e3-c546-d5c4ba2b3142 ONLINE 0 0 0
> gptid/209e8c9c-ff66-6f6a-e38b-9045c0b6c3ec ONLINE 0 0 0
> gptid/ea8b834a-0692-464b-fd29-a877bf8f7bb9 ONLINE 0 0 0
> gptid/cf35d740-ea0b-bae6-9e4f-b7a31d66ab1d ONLINE 0 0 0
> gptid/fe908e73-c93b-72ed-d4bb-9eae78bcc5b6 ONLINE 0 0 0
> gptid/bdf03e4d-ba71-a4cc-dd90-edfd6446bac3 ONLINE 0 0 0
> gptid/302bacc1-273a-54c9-c8f9-f458640b0d60 ONLINE 0 0 0
> gptid/d94ea326-d5aa-f062-9662-953908ce0b53 ONLINE 0 0 0 raidz2-1 ONLINE 0 0
> 0 gptid/3c1b1d3b-3977-11e6-b1f0-0025902b035a ONLINE 0 0 0
> gptid/3ec0ba4a-3977-11e6-b1f0-0025902b035a ONLINE 0 0 0
> gptid/40d8b781-3977-11e6-b1f0-0025902b035a ONLINE 0 0 0
> gptid/43387eae-3977-11e6-b1f0-0025902b035a ONLINE 0 0 0
> gptid/45800439-3977-11e6-b1f0-0025902b035a ONLINE 0 0 0
> gptid/47df2694-3977-11e6-b1f0-0025902b035a ONLINE 0 0 0 da2 ONLINE 0 0 0 |
> 
> |```|
> ||
> 
> |Note that pool |||pdx-zfs-02| consists of two |||raidz2| devices with
> different numbers of disks in them and a disk da2. You can have pool to be
> very heterogeneous.|
>