Michael's Daemonic Doodles

...blogging bits of BSD

Shrinking a ZFS root pool (HDD to SSD migration)

I recently started migrating servers with relatively low storage space requirements to SSDs. In many cases the HDDs that get replaced are much bigger than required and unfortunately the zpools have been configured to use all the available space. Since shrinking a pool is not supported by ZFS directly, the procedure is a little more elaborate.


Setting up FreeBSD on ZFS raidz2 using mfsBSD

As I explained in an earlier post, we had issues with one of our backup servers. I decided to do a complete reinstall and ended up using an LSI SAS 9211 controller running in initiator-target mode (IT firmware), so all eight disks show up as plain HBAs and can be used to form a zpool. After considering my options I decided to go with raidz2, which will provide a good balance of storage space and safety.


Preparing an LSI SAS 2008 based controller for ZFS

In my last post I wrote about how the Adaptec 5805 RAID controller was the wrong choice for our backup server. So I started some research, based on the following criteria:

  • Production quality driver (so no more crashes, hangs and other weird behavior)
  • Pass-through support (/dev/passX), including S.M.A.R.T.
  • JBOD support (disks should show up as devices /dev/daX)
  • Decent throughput
  • Existing success stories with ZFS
  • Reasonable price and availability


Adaptec Madness (or why I started this blog)

One of the less maintained machines in our data center is a small backup server. It's basically sitting there, storing all those backups nobody really uses and slowly fills up its disk array. Once in a while somebody checks it manually to see if everything's in order (it has never been really connected to anything sitting on its own isolated VLAN).

The server uses an Adaptec 5805 controller, a product line I tried debugging and fixing a long time ago (see also http://lists.freebsd.org/pipermail/freebsd-bugs/2009-June/035612.html). Unfortunately back then our supplier stated that this is the only controller certified for this machine - so I gave in, hoping that a pretty much bored backup server won't have too much trouble keeping up with the little load it would get.

I was wrong.