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I have a storage with ZFS and Debian wheezy. I am always using the latest ZFS from their github. I created 3 different raidz-3 pools. One for every controller. On every controller I have 24x 4T SATA disks. If I use the backup pools only for Linux Backups and NFS everything is ok. As soon as I allocate volume for the Microsoft's DPM and It is starting to back up It keeps eating up all the diskspace I have in one pool. As you can see below the bm-backup volume is 20TB in size, but it is using much more.

Please tell me how can I limit the data used by a volume? What can I do now? Only to destroy and recreate bm-backup? But every month?

Please help me with the right settings/commands I need to maintain volumes with ZFS on linux.

Thank you.

You can see the relevant information below:

uname -a

Linux storage6 3.2.0-4-amd64 #1 SMP Debian 3.2.63-2+deb7u2 x86_64 GNU/Linux

ZFS version:

[   11.200794] ZFS: Loaded module v0.6.3-159_gc944be5, ZFS pool version 5000, ZFS filesystem version 5
[   10.916233] SPL: Loaded module v0.6.3-52_g52479ec
[   12.829561] SPL: using hostid 0x00000000

history for storage-02:

2014-12-09.12:58:47 zpool create -m none -o ashift=12 storage-02 raidz3 ...
2014-12-19.11:34:43 zfs create -V 20T storage-02/bm-backup
2014-12-19.11:54:40 zfs set reservation=1T storage-02/bm-backup

zpool list:

NAME         SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
storage-02    87T  85.5T  1.47T         -    41%    98%  1.00x  ONLINE  -
storage-03    87T  30.2T  56.8T         -    25%    34%  1.00x  ONLINE  -
storage-81    87T  67.1T  19.9T         -    15%    77%  1.00x  ONLINE  -

zfs get storage-02/bm-backup:

NAME                  PROPERTY              VALUE                  SOURCE
storage-02/bm-backup  type                  volume                 -
storage-02/bm-backup  creation              Fri Dec 19 11:34 2014  -
storage-02/bm-backup  used                  64.9T                  -
storage-02/bm-backup  available             88.7G                  -
storage-02/bm-backup  referenced            64.9T                  -
storage-02/bm-backup  compressratio         1.00x                  -
storage-02/bm-backup  reservation           1T                     local
storage-02/bm-backup  volsize               20T                    local
storage-02/bm-backup  volblocksize          8K                     -
storage-02/bm-backup  checksum              on                     default
storage-02/bm-backup  compression           off                    default
storage-02/bm-backup  readonly              off                    default
storage-02/bm-backup  copies                1                      default
storage-02/bm-backup  refreservation        20.6T                  local
storage-02/bm-backup  primarycache          all                    default
storage-02/bm-backup  secondarycache        all                    default
storage-02/bm-backup  usedbysnapshots       0                      -
storage-02/bm-backup  usedbydataset         64.9T                  -
storage-02/bm-backup  usedbychildren        0                      -
storage-02/bm-backup  usedbyrefreservation  0                      -
storage-02/bm-backup  logbias               latency                default
storage-02/bm-backup  dedup                 off                    default
storage-02/bm-backup  mlslabel              none                   default
storage-02/bm-backup  sync                  standard               default
storage-02/bm-backup  refcompressratio      1.00x                  -
storage-02/bm-backup  written               64.9T                  -
storage-02/bm-backup  logicalused           20.1T                  -
storage-02/bm-backup  logicalreferenced     20.1T                  -
storage-02/bm-backup  snapdev               hidden                 default
storage-02/bm-backup  context               none                   default
storage-02/bm-backup  fscontext             none                   default
storage-02/bm-backup  defcontext            none                   default
storage-02/bm-backup  rootcontext           none                   default
storage-02/bm-backup  redundant_metadata    all                    default
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Finally I have found 2 solutions.

1) Leave the ashift on default value, even if the blogs/docs say otherwise.

2) Increase the volblocksize to 64K with raidz3.

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