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Where to put ZFS filesystems in a pool

October 27, 2006

Before we had ZFS, I was always telling people not not put things in the root of a file system. Specifically don’t share the root of a file sytem. That way if you want to add another share to the file system later with different permissions you could and all was good. It was (is) good advice.

With ZFS you end up with lots of file systems and the advice does not hold anymore. Where previously you were trying to share the file system resources now you would just create a new file system in a pool and have done with it.

Today I realized that for ZFS there is some similar advice worth following and that is don’t put all your file systems in the root of the pool. Todays example is that I have a number of file systems and one zvol in a pool. It would be nice to be able to use a single recursive snapshot to back up all the file systems but not the zvol, since that zvol is my swap partition. While a snapshot of swap is kind of cool in that you can do it serves no purpose other than to use storage at an alarming rate.

So now I have moved all the file systems under one uber filesystem called “fs”:

# zfs list -t filesystem,volume NAME                              USED  AVAIL  REFER  MOUNTPOINT tank                             84.9G   187G  26.5K  /tank tank/fs                          82.8G   187G  32.5K  /tank/fs tank/fs/downloads                31.9G   187G  2.20G  /tank/fs/downloads tank/fs/downloads/nv             26.9G   187G  37.5K  /tank/fs/downloads/nv tank/fs/downloads/nv/46          2.49G   187G  2.48G  /tank/fs/downloads/nv/46 tank/fs/downloads/nv/47          2.45G   187G  2.45G  /tank/fs/downloads/nv/47 tank/fs/downloads/nv/48          2.55G   187G  2.45G  /tank/fs/downloads/nv/48 tank/fs/downloads/nv/49          2.46G   187G  2.45G  /tank/fs/downloads/nv/49 tank/fs/downloads/nv/50          2.52G   187G  2.45G  /tank/fs/downloads/nv/50 tank/fs/downloads/nv/51          2.50G   187G  2.46G  /tank/fs/downloads/nv/51 tank/fs/downloads/nv/tmp         12.0G   187G  4.78G  /tank/fs/downloads/nv/tmp tank/fs/local                    66.8M   187G  57.0M  /tank/fs/local tank/fs/opt                      1.67G  28.3G  25.5K  /tank/fs/opt tank/fs/opt/SUNWspro              459M  28.3G   453M  /opt/SUNWspro tank/fs/opt/csw                   340M  28.3G   121M  /opt/csw tank/fs/opt/sfw                   907M  28.3G   880M  /opt/sfw tank/fs/opt/spamd                 110K  28.3G  24.5K  /tank/fs/opt/spamd tank/fs/shared                   12.1G  37.9G  28.5K  /tank/fs/shared tank/fs/shared/music             5.71G  37.9G  5.70G  /tank/fs/shared/music tank/fs/shared/pics              6.36G  37.9G  6.32G  /tank/fs/shared/pics tank/fs/shared/projects           424K  37.9G  25.5K  /tank/fs/shared/projects tank/fs/shared/projects/kitchen   376K  37.9G  46.5K  /tank/fs/shared/projects/kitchen tank/fs/users                    25.4G  74.6G  32.5K  /tank/fs/users tank/fs/users/user1               300K  74.6G  29.5K  /tank/fs/users/user1 tank/fs/users/user1              23.1G  74.6G  22.2G  /tank/fs/users/user2 tank/fs/users/user3              13.5M  74.6G  9.72M  /tank/fs/users/user3 tank/fs/users/user4               652M  74.6G   614M  /tank/fs/users/user4 tank/fs/users/user5              1.12G  74.6G   987M  /tank/fs/users/user5 tank/fs/users/user6               500M  74.6G   341M  /tank/fs/users/user6 tank/fs/var                      10.8G  19.2G  35.5K  /tank/fs/var tank/fs/var/crash                5.10G  19.2G  5.09G  /var/crash tank/fs/var/dhcp                  128K  19.2G    30K  /tank/fs/var/dhcp tank/fs/var/log                  49.5K  19.2G    27K  /tank/fs/var/log tank/fs/var/mail                  871M  19.2G   179M  /var/mail tank/fs/var/mqueue                662K  19.2G  24.5K  /var/spool/mqueue tank/fs/var/named                 442K  19.2G   369K  /tank/fs/var/named tank/fs/var/openldap-data         130K  19.2G  82.5K  /tank/fs/var/openldap-datatank/fs/var/opt                    46K  19.2G  24.5K  /tank/fs/var/opt tank/fs/var/samba                  46K  19.2G  24.5K  /tank/fs/var/samba tank/fs/var/tmp                  4.90G  19.2G  2.45G  /tank/fs/var/tmp tank/fs/web                       920M   104M  2.56M  /tank/fs/web tank/swap                        45.1M   189G  45.1M  –


I could have tweaked the mount point of tank to be “none” and of tank/fs to be “tank” but did not to avoid potential confusion in the future. I should really also ask that “zfs snapshot -r” have a -t option so you could get it to snapshot based on a type.

Tags: topic:[ZFS] topic:[Home Server]


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From → Solaris

2 Comments
  1. Is there any actual reason to place swap on zfs beyond it being neat?
    I mean, I’ve done it as well, but that has more to do with my zfs drives being the fastest ones in my system, but I can’t think of any other benefit

  2. Yes there is a reason.
    I want to reduce the risk of the kernel getting back corrupt data from swap.

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