[BackupPC-users] ZFS/Nexenta Ready

[dan <dan...@gm...>]

Just an FYI for those interested.  Nexenta Core 2 (based on ubuntu 8.04) is
out and runs backuppc great.

The only issue was that ping is not in /bin/ping, its in /usr/sbin/ping so
you have to create a link.

Also, exim is what wants to be installed and it is not very functional, just
install postfix to clear that up.

Here is a little rundown of why to try nexenta and zfs for backuppc

The ONLY distribution that has backuppc available in the repos (bpc3.0)

opensolaris kernel which gives you a very very fast network stack, faster
than linux.

ZFS
1)gives you on-filesystem compression.  I know that backuppc provides this
but you can turn off compression in backuppc and use the in-filesystem
backup for better write performance.  I get slightly better compression
ratios with ZFS' default compression (lzo) and slightly better backup times,
about 4 or 5% on each.
2) I/O buffers.  This essentially caches I/O and re-orders it for more
sequential writes.  The benefit here is that it makes your disk seem like it
has much better I/O performance especially with heavy I/O loads like
backuppc puts on the system.
3)free snapshots.  you can shut down backuppc, take an instant snapshot, and
start it back up and you will have a point in time snapshot that you can
sync against another machine or pull off to external media for storage.
4)block level tranport.  You can transport a ZFS volume from one server to
another over TCP/IP.  This is nice if you want to replicate your ZFS
backuppc store to another machine because you can take a snapshot, send it
over to a new machine, and promote that snapshot.  They you can do
incremental snapshots in the future and send them over, only transfering the
blocks that changed.  requires some fance scripting but is very doable.
5)SSD for backuppc.  Solid state disks just dont have the capacity to be
primary backup solutions but they do have the I/O performance that we want.
With ZFS you can put a SSD in as a cache disk and take advantage of the fast
I/O and it will dump sequential writes to your spindled drives.  This can
help a lot.  I have only been able to test it with a slower OCZ SSD but I
clocked a 5% improvement in backup times that was repeatable.  I think a
faster SSD could really make a big difference.

The down side is that you might have some learning curve with the
opensolaris kernel, but the environment is very much ubuntu.  Also, ZFS is a
memory hog.  You really need to have 2GB+ RAM.  You can pretty much get by
with that as ZFS can control itself with 2GB but if you only have 1GB then
the filesystem will eat up all of it and your system will not behave itself.
You might also have some driver issues if you have 1-off hardware or an old
system as opensolaris does not have the extensive hardware support of a
linux system.

There are tons of other benefits but none that I can think are relevant to
backuppc.