Incorrect free space reporting for ZFS datasets (Homepage dashboard)

[arabesc]

I am using the Homepage dashboard, which utilizes the SystemInformation library to retrieve storage information.

I have configured a storage widget to monitor a specific ZFS dataset:

- resources:
    label: Storage
    expanded: true
    disk: /mnt/storage

This dataset has several child datasets where the primary data is stored. Currently, the dashboard incorrectly reports the free space, showing the storage as almost entirely empty:

{
    "fs": "zstore",
    "type": "zfs",
    "size": 44307352634368,
    "used": 196608,
    "available": 44307352437760,
    "use": 0,
    "mount": "/mnt/storage",
    "rw": true
}

It appears that when reporting space for a ZFS dataset, the library does not account for the data stored within its child datasets, leading to inaccurate "used" space readings.

Current Output

Expected behavior

# zfs list zstore
NAME     USED  AVAIL  REFER  MOUNTPOINT
zstore  24.7T  40.3T   192K  /mnt/storage

Environment:

• Homepage v1.8.0 (have no idea which version of SystemInformation is bundled with that Homepage release)
• OS: FreeBSD 14.3, ZFS

Originally reported in gethomepage/homepage#6127

[sebhildebrandt]

@arabesc ... so https://github.com/gethomepage/homepage seems to use "systeminformation": "^5.27.11" as a dependency, so a quite recent version. In the original issue I can see that this function is called: si.fsSize()

So let us see ... your ZFS storage is mounted at /mnt/storage

The command zfs list zstore reports:

NAME     USED  AVAIL  REFER  MOUNTPOINT
zstore  24.7T  40.3T   192K  /mnt/storage

which would mean, we have 24,7 used, 40,3T avail and overall size is then aprox 65T? Can you confirm that?

systeminformation fsSize() reports other values:

• "size": 44307352634368
• "available": 44307352437760

So what seems to be wrong: fsSize() does not report the correct full size ...??

To be able to fix this I would need the following: These are the underlying commands:

df -lkPT
mount

Can you execute them in the command line and post the results (as text) here ... Thank you In advance!

[sebhildebrandt]

@arabesc and can you add the output of

zfs list

[sebhildebrandt]

@arabesc Or even better:

zfs list -H -p -o name,used,usedds,usedsnap,avail,refer,mountpoint -d 0

[arabesc]

which would mean, we have 24,7 used, 40,3T used and overall size is then aprox 65T? Can you confirm that?

No, 40,3T is the total size of the pool.

So what seems to be wrong: fsSize() does not report the correct full size ...??

The full size is correct, the used size is incorrect.

Can you execute them in the command line and post the results (as text) here ... Thank you In advance!

# df -lkPT
zstore                         zfs     43011993003         192 43011992811     0%    /mnt/storage
zstore/owncloud                zfs     43014208238     2215426 43011992811     0%    /mnt/storage/owncloud
zstore/temp                    zfs     43011992987         176 43011992811     0%    /mnt/storage/temp
zstore/users                   zfs     43011992987         176 43011992811     0%    /mnt/storage/users
zstore/media                   zfs     43012021535       28724 43011992811     0%    /mnt/storage/media
zstore/plex                    zfs     43011992987         176 43011992811     0%    /mnt/storage/plex
zstore/calibre                 zfs     43229345362   217352550 43011992811     1%    /mnt/storage/calibre
zstore/plex/data               zfs     43086956477    74963666 43011992811     0%    /mnt/storage/plex/data
zstore/btsync                  zfs     43011992987         176 43011992811     0%    /mnt/storage/btsync
zstore/media/music             zfs     43040166303    28173492 43011992811     0%    /mnt/storage/media/music
zstore/media/video             zfs     61336342542 18324349731 43011992811    30%    /mnt/storage/media/video
zstore/media/magazines         zfs     43016903203     4910392 43011992811     0%    /mnt/storage/media/magazines
zstore/mysql                   zfs     43011993019         208 43011992811     0%    /mnt/storage/mysql
zstore/media/education         zfs     44299228365  1287235553 43011992811     3%    /mnt/storage/media/education
zstore/torrents                zfs     43318003840   306011029 43011992811     1%    /mnt/storage/torrents
zstore/plex/backup             zfs     43012702733      709922 43011992811     0%    /mnt/storage/plex/backup
zstore/media/books             zfs     43017282640     5289829 43011992811     0%    /mnt/storage/media/books
zstore/media/personal          zfs     44836140500  1824147688 43011992811     4%    /mnt/storage/media/personal
zstore/mysql/data              zfs     43012012264       19453 43011992811     0%    /mnt/storage/mysql/data
zstore/mysql/log               zfs     43012333446      340635 43011992811     0%    /mnt/storage/mysql/log
zstore/qbittorrent             zfs     43011993019         208 43011992811     0%    /mnt/storage/qbittorrent
zstore/qbittorrent/downloads   zfs     45920799947  2908807135 43011992811     6%    /mnt/storage/qbittorrent/downloads
zstore/qbittorrent/temp        zfs     43098258157    86265346 43011992811     0%    /mnt/storage/qbittorrent/temp

# mount
zstore on /mnt/storage (zfs, local, noatime, nfsv4acls)
zstore/owncloud on /mnt/storage/owncloud (zfs, local, noatime, noexec, nfsv4acls)
zstore/temp on /mnt/storage/temp (zfs, local, noatime, nfsv4acls)
zstore/users on /mnt/storage/users (zfs, local, noatime, nfsv4acls)
zstore/media on /mnt/storage/media (zfs, local, noatime, nfsv4acls)
zstore/plex on /mnt/storage/plex (zfs, local, noatime, nfsv4acls)
zstore/calibre on /mnt/storage/calibre (zfs, local, noatime, nfsv4acls)
zstore/plex/data on /mnt/storage/plex/data (zfs, local, noatime, nfsv4acls)
zstore/btsync on /mnt/storage/btsync (zfs, local, noatime, nfsv4acls)
zstore/media/music on /mnt/storage/media/music (zfs, local, noatime, nfsv4acls)
zstore/media/video on /mnt/storage/media/video (zfs, local, noatime, nfsv4acls)
zstore/media/magazines on /mnt/storage/media/magazines (zfs, local, noatime, noexec, nfsv4acls)
zstore/mysql on /mnt/storage/mysql (zfs, local, noatime, nfsv4acls)
zstore/media/education on /mnt/storage/media/education (zfs, local, noatime, nfsv4acls)
zstore/torrents on /mnt/storage/torrents (zfs, local, noatime, nfsv4acls)
zstore/plex/backup on /mnt/storage/plex/backup (zfs, local, noatime, nfsv4acls)
zstore/media/books on /mnt/storage/media/books (zfs, local, noatime, nfsv4acls)
zstore/media/personal on /mnt/storage/media/personal (zfs, local, noatime, nfsv4acls)
zstore/mysql/data on /mnt/storage/mysql/data (zfs, local, noatime, nfsv4acls)
zstore/mysql/log on /mnt/storage/mysql/log (zfs, local, noatime, nfsv4acls)
zstore/qbittorrent on /mnt/storage/qbittorrent (zfs, local, noatime, nfsv4acls)
zstore/qbittorrent/downloads on /mnt/storage/qbittorrent/downloads (zfs, local, noatime, nfsv4acls)
zstore/qbittorrent/temp on /mnt/storage/qbittorrent/temp (zfs, local, noatime, nfsv4acls)

# zfs list -H -p -o name,used,usedds,usedsnap,avail,refer,mountpoint -d 0
zstore  27468535476360  196416  0       44044280614776  196416  /mnt/storage

The last output seems to has the right used size.

[sebhildebrandt]

@arabesc zfs list claims we have 27468535476360 bytes used and 44044280614776 bytes available which result in 65T ... I am confused as you are saying the pool has 44T

• USED: the total space for a dataset and all its children (sub-filesystems, snapshots), including shared blocks, counting space hierarchically
• AVAIL: this column indicates free space, meaning how much new data you can write before hitting limits

[sebhildebrandt]

@arabesc ... so if you are adding e.g. a large file to your storage ... my guess is that the above command no longer shows the same AVAIL value

[arabesc]

zfs list claims we have 27468535476360 bytes used and 44044280614776 bytes available which result in 65T ... I am confused as you are saying the pool has 44T

You are right, sorry for confusion. I forget the total size of my storage...

# zfs list -p -H -o used,avail zstore | awk '{printf "%.2f TB\n", ($1 + $2) / 1024^4}'
65.04 TB

[sebhildebrandt]

@arabesc Ok, so this is sorted out ... :-)

Well the thing is, the underlying commands I currently use do not include zfs list ... as this would only be relevant for certain file system types ... I need to think, how I can add this to get proper results for zfs ...

Alternatively I can use the results from df and make some more calculations ... this is not 100% correct but we would get quite good approximation.

[Rembold04]

I just wanted to add that I am experiencing the same issue on an Unraid host when using ZFS. Homepage is displaying the total disk size as the current free space on any pool or individual disk that uses ZFS.

The exception is the array (as a whole) since that is multiple ZFS disks together; its information appears to be correct.

In my case the values for Array are correct. Cache is actually a ZFS mirror with 3.66/3.84 TB. The first disk (solo ZFS) is 9.01/13.8 TB. The other three disks are currently correct, but only because there is no data written to them yet.

[sebhildebrandt]

@Rembold04 ... thank you for providing more context here. Currently working on a solution for that.

[sebhildebrandt]

@Rembold04 ... me once again... to be able to fix this I would need the exact output (command line) on your machine (unraid, correct? This should be a modified slackware distro) for:

export LC_ALL=C; df -lkPTx squashfs; unset LC_ALL
cat /proc/mounts 2>/dev/null
zfs list -H -p -o name,used,usedds,usedsnap,avail,refer,mountpoint -d 0

I will mock my code with your output to see, what I can achieve ...

Thank you in advance

[Rembold04]

Correct, this is an Unraid machine. I don't know how much you know about Unraid, but it does parity differently. Disks 1-4 are part of the array and each disk is using ZFS, but not in a RAID. Parity/data is not striped across all disks in the array. I am not sure if that makes any difference, but wanted to make you aware of that.

I attached the output as a file. I can't get the formatting to stay intact in this text editor.

ZFS Disk Info.txt

[sebhildebrandt]

@Rembold04 thank you ... can you also post, what we actually get from systeminformation?

git clone https://github.com/sebhildebrandt/systeminformation.git
cd systeminformation
npm run test

Then press key f to get assize

Thank you in advance!

[Rembold04]

Is there a docker container that I can mount the root filesystem on which already has git and npm installed? Unraid is based on a limited feature version of Slackware. You are not supposed to install things via command line. While I am familiar with Linux, finding an existing Docker container or one that I can install git/npm on is over my head. systeminformation is being used in the Homepage app via Docker so I have not had to directly install anything.

Or is this something @arabesc can run for you?