[CDBUG-talk] Slow ZFS and/or Backup/recovery question

Steve Moon steve.moon at gmail.com
Tue Nov 1 23:41:28 EDT 2016

I recently resurrected an old laptop and loaded FreeBSD 11 and ended up
really liking it.

So far so good.

The laptop started with a dead hard drive that I swapped out with a
different drive. While the original drive worked fine with the "AHCI" BIOS
setting, the new drive The laptop freezes at the BIOS screen unless AHCI is
changed to compatible (IDE) mode.

The drive seemed to work fine when I fired it up, I got Ubuntu installed
with no issues, started over with FreeBSD, re-installed clean a couple of
times, finally just went with a ZFS root and everything seemed okay. I got
X configured, but noticed it got _really_ slow.

diskinfo -t /dev/ada0 shows some stunningly poor disk performance - like
1MB/s reads.

I've done a lot of research on ZFS and tweaked some settings in loader.conf
but to no avail - the disk is slow.

So I've either got a slow disk, perhaps because it is in the process of
dying, or there is some kind of incompatibility with ZFS and the IDE mode
(some googling showed a few places where AHCI is suggested over ZFS).

I have no real use for ZFS other than the novelty value. It's not like a
300GB SATA disk on an old consumer-grade Lenovo Z560 laptop with 4GB RAM is
going to exercise ZFS.

However I did do a lot of tweaking, installing packages and ports, etc. etc.

So to the questions:
1. Has anyone had similar issues with ZFS - could it just be that?
2. Either way - ZFS or hardware - any suggestions on how I could back up
the various configurations and package/port installs and then re-install
them on top of a fresh install on a new disk? Linux Mint had a "upgrade"
option that basically dumped a list of installed packages and after a fresh
install of the new version of Mint you'd "apply" that to get your stuff
re-installed. It looks like that may have changed, but it was slick the
time or two I used it.

I see I could run something like: pkg query --all '%o %n-%v %R'
- then manually get that stuff re-installed after a clean install.

Anyone have any other ideas? The disk is so slow it might take 24+ hours to
use dump, tar, or the like, and I'd like to ditch ZFS anyway.

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