Thanks!
Could you also let us know the output of "stat --file-system /home".
It returned:
File: "/home"
ID: fd0700000000 Namelen: 255 Type: xfs
Block size: 4096 Fundamental block size: 4096
Blocks: Total: 268304384 Free: 40718553 Available: 40718553
Inodes: Total: 107374144 Free: 95704253
Stratis uses a constant threshold of filesystem usage to determine if
the filesystem should
be expanded.
I think it is possible that a devicemapper event triggers the
filesystem check, but the
threshold has not yet been reached and so no expansion action is taken.
It looks like the snapshots are very similar to their origins;
otherwise the pool used
amount would be much larger, so I don't see why they should have any
effect.
- mulhern
On Thu, Sep 16, 2021 at 10:49 PM Ryan Gonzalez <rymg19(a)gmail.com
<mailto:rymg19@gmail.com>> wrote:
On 9/16/21 9:23 PM, the Mulhern wrote:
> Hi!
>
> One thing I'ld like to mention is that in Stratis 3.0, you'll
> be able to set the size of the filesystem at the command-line,
> although the default size will remain 1 TiB. There are some caveats;
> it's not a good idea to grow an xfs filesystem by more than about 8
> times as the metadata layout is calculated for the original size
> specified.
So just for some clarity, if I had to make the rootfs smaller to
make room for home to expand, would the only way to do that to be
to wait for 3.0, then just re-create the FS with a smaller initial
size? I don't anticipate it nearly growing past 8x the original size.
>
> But, while this might be useful to others, I don't think it's really
> all that relevant to your case. The amount of space allocated by the
> thinpool for your data should really correspond to your filesystem
> usage, which is only about 1 TiB.
>
> Generally speaking, Stratis responds to devicemapper events,
> including
> the low water event. It then does an analysis of your pool,
> including the
> filesystems, to determine if any adjustment should be made.
>
> Can you show us the output of the "stratis pool list" command? That
> should show both the amount of space actually used (by your data +
> Stratis metadata) the total size as understood by Stratis, and
> the amount
> that Stratis interprets as free.
>
This is the output:
Name Total Physical
Properties UUID
fedora 1.81 TiB / 1.06 TiB / 769.29 GiB ~Ca, Cr
d9c81a12-b249-4c4c-ae7b-afe658911993
In case it helps, here's also the output of `fs list`:
Pool Name Name Used Created Device UUID
fedora root_backup 125.42 GiB Sep 05 2021 17:34
/dev/stratis/fedora/root_backup 4d2e3dc8-8b30-44f2-b2e9-d7be3f257784
fedora home_backup 895.84 GiB Sep 05 2021 17:33
/dev/stratis/fedora/home_backup a96b7544-5047-461e-baee-f33311be9643
fedora home 897.71 GiB Sep 04 2021 22:54
/dev/stratis/fedora/home 80d9ffe8-f686-4c5c-9b2c-b9380d9a8309
fedora root 122.97 GiB Sep 04 2021 22:53
/dev/stratis/fedora/root 70398648-899d-426d-981f-313706768233
I...just realized I still have these snapshots lying around that I
was (trying to) use for backup purposes, could that be affecting
things as well?
> From what you tell me, I think it's possible that, during I/O,
> the low water
> mark is reset multiple times by stratisd, and also crossed
> multiple times,
> triggering repeated re-evaluations of the pool and filesystem
> states, which
> perhaps then result in no action, but cause the slow I/O that you
> mentioned.
>
> You can't prevent Stratis from doing this check, without
> accepting a patch and
> recompiling. This check is there to prevent running out of space,
> so it's
> not optional. It is our present goal to make these checks more
> effective and less intrusive.
> In fact, we just today merged a PR[1] which inaugurates
> our development efforts on thinpool and filesystem management
> improvements.
>
> Thanks for getting in touch,
>
> - mulhern
>
> [1]
https://github.com/stratis-storage/stratisd/pull/2786
> <
https://github.com/stratis-storage/stratisd/pull/2786>
>
>
>
>
>
>
>
>
>
>
>
>
> On Thu, Sep 16, 2021 at 8:45 PM Ryan Gonzalez <rymg19(a)gmail.com
> <mailto:rymg19@gmail.com>> wrote:
>
> Hello there again! I've been using Stratis as my rootfs for a
> bit now,
> and it seems to be working pretty well...with one particular
> catch...
>
> For some context: I have a single 2TB pool on a single disk,
> with two
> filesystems inside. When I created said filesystems, they
> seem to have
> been both sized as 1TB, which was a bit confusing since I
> thought they
> would start smaller and expand as I wrote to them. In
> particular, one of
> them (the rootfs) is only ~200GB full, while the other is
> ~800GB. Of
> course, the latter of these is reaching the current 1TB
> limit, which is
> where things get...weird. In particular, based on the system
> logs, I
> seem to have hit this:
>
https://github.com/stratis-storage/stratisd/issues/1466
> <
https://github.com/stratis-storage/stratisd/issues/1466>
>
> From what I can understand, this is just Stratis trying to
> expand the
> filesystem. However...it doesn't seem to ever succeed, since
> the size
> stays the same. Despite that, it still seems to run whenever
> I write in
> a large amount of new data, resulting in some *very* brutally
> slow I/O
> speeds (despite being on an NVMe disk), to the extent that I
> can't
> really even open a terminal (to be fair, I have quite a few
> oh-my-zsh
> plugins that could be contributing negatively to this...)
>
> This has led to two particular questions:
>
> - How exactly does the resizing of filesystems work? I know
> you can't
> shrink XFS, but I believe the Stratis design paper references
> reclaiming
> unused space via trims. Is it even possible for the rootfs to
> "shrink"
> (but not really) to accommodate an expansion of the other one?
>
> - If the other one can't expand, is it possible to just tell
> Stratis to
> stop trying and avoid the major lag? Or, could there be
> something in my
> configuration making this significantly slower than it's
> supposed to be
> (maybe disk schedulers)?
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