Having little experience with git, and none with bup, I wonder how bup
compares to Obnam. I've been testing Obnam lately and it seems to
work quite well for remote backups of large files; its bottleneck
seems to be SFTP RTT command latency when backing up many small files
(though I think Lars may address that eventually). But its feature
set is quite impressive, and I also like its thorough build-time
brackup also sounds interesting, but I haven't even touched it yet.
What I do know is that, while it's a reliable and powerful tool,
Duplicity falls short when it comes to removing old backup data and
restoring even small files from long chains.
Thanks for any thoughts.
I liked it, but found it intolerably slow.
If it uploads small files one by one, then it definitely doesn't have
the potential to be as fast as bup. However, bup currently doesn't
support sftp. I really think someone should make a try at an sftp
version of 'bup server' - it would probably not be very hard, and
would be pretty cool.
Alternatively, David Anderson recently repackaged the "upload yourself
to the server" feature of my sshuttle program to make it more flexible
and reusable. With that package, it should actually be possible for
bup to upload itself to the remote end (even if the remote end doesn't
have bup installed) and run the very efficient bup-server protocol
that way. If you have sftp access, you probably have full ssh access,
right? So that would be pretty powerful.
One of bup's claims is very fast backing up of VM images. I tried
this, and it seems to have decent speed backing up, but restoring is
very slow. I'm guessing it's because of the 8 KB chunks? (Assuming I
understand bup correctly.)
In contrast, Obnam backs up faster than bup, and also restores much
faster: restoring a 15 GB VirtualBox image took 27 minutes with Obnam
vs. 47 minutes for bup.
Is there a way to tweak bup to make it faster, maybe using larger
chunks, or is Obnam just faster for this scenario?
> Thanks for your replies.
> One of bup's claims is very fast backing up of VM images. I tried
> this, and it seems to have decent speed backing up, but restoring is
> very slow. I'm guessing it's because of the 8 KB chunks? (Assuming I
> understand bup correctly.)
> In contrast, Obnam backs up faster than bup, and also restores much
> faster: restoring a 15 GB VirtualBox image took 27 minutes with Obnam
> vs. 47 minutes for bup.
When you do the restores, what are the cpu and disk loads?
It would be interesting to create a composite performance metric for
measuring backup systems. My personal weighting is that the 47 vs 27
restore time is not a big deal and I'm more concerned with backup time,
space efficiency, correctness of backup of a changing filesystem (where
matching each file either before or after is ok) and especially the
probability of actually getting data back. But, all other things equal,
if it can be sped up that's great.
Adam- are you using spinning platter media?
This is unedited.
This test I did was on my Acer Aspire One netbook--not a powerhouse by
any means! I'm sure my other systems would have done it more quickly.
However, I was only interested in the times relative to each other.
And, yes, it was on a single, local hard disk, both the backup repo
and the restore target.
I'm not an expert on Obnam either, but from what I can tell, it uses
chunks up to at least 1.1 MB, which is much larger than 8 KB.
I think you will find obnam slows to a crawl when going over the net.
That may not be important for you, but if it is, be sure to test.
I did mention this in the first post. :) For small files, Obnam over
the net is quite slow. For large files, the chunks are large enough
that it seems to do about as well as, say, Duplicity. I guess you
mean that bup is fast over the net even for small files--but since it
doesn't encrypt, it's not as useful for network backups for me.
Do you have a link for us to read about this?