Re: Any advice for a user about to use LVM for the first time?
On 01/01/2015 05:41 PM, D. R. Evans wrote:
David Christensen wrote on 01/01/2015 05:53 PM:
restore). More recently, I learned enough zfs-fuse for single and
mirrored data drives. I later migrated to ZOL for performance.
Administration of ZFS file systems requires a lot more knowledge and
planning.
This must be one of those YMMV things, because I have systems with both kinds
of RAID, and I find ZFS to be vastly easier to administer (and, in fact,
superior in every way
Sun did an excellent job with ZFS. It has "conceptual integrity" and is
truly a "systems programming product".
However, ZFS includes a time dimension (snapshots), which adds a whole
new level of complexity once you're up the initial "it works" portion of
the learning curve -- especially with respect to organization/
reorganization and backup/ recovery. For example, let's say I have an
existing file system and I want to move a subtree into another file
system. On technologies without the time dimension, there is only the
present and 'mv' is all you need. With ZFS, you need to understand
snapshots, replication, clones, and/or promotion in order to deal with
the present and the past. Similarly, when restoring a subtree from
backup when the source file system has additional snapshots. It's very
easily to goof up one step and lose information, which is especially
painful when you're talking large amounts of data and each operation
takes hours to complete. I ended up writing a Perl module and scripts
to encapsulate common ZFS operations, to obtain safety, correctness, and
consistency.
except the extremely annoying license incompatibility
whose result is that one can't boot from a ZFS drive into debian).
Agreed. Apparently, some Linux distributions have figured out a
solution. Debian needs full ZFS integration.
And since ZOL is not integrated into Debian, I had to invent
scripts to get things mounted at boot and cleanly unmounted at shutdown.
I don't know why you had to do that. I have in the past few days put ZoL on a
brand new debian system, and the ZFS pools are mounted and unmounted exactly
as one would hope, without any intervention from me.
I started with ZOL 0.6.2. Perhaps 0.6.3 fixed boot/ mount and shutdown/
unmount and I didn't notice.
If you are trying to use ZFS for /boot or some of the other system
hierarchies, then I can see how you would have a problem that would likely
require home-grown scripts;
Agreed. ZFS boot, root, and swap on Debian GNU/ Linux is beyond my
threshold.
Perhaps someone with mdadm experience can offer some pointers for
learning enough mdadm to set up RAID 0.
I did it by trial-and-error (as I "learn" most things) and I have to say that
it took a lot longer than the same process did for ZFS. The Arch wiki, I
recall, was the most useful single resource.
Thanks for the pointer.
David
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