Hi everyone,

I'm working on setting up some Amanda backups at my house and have run
into a serious performance problem.  Both the client and the server
machine are using LVM2 for their disks.  Though there's 320GiB of data
to backup, this is a bit ridiculous:

sendbackup: time 8008.486:  87:  normal(|):   DUMP: 8.07% done at 3472 kB/s, 
finished in 24:40

I've done tons of dumps to LVM volumes on a server with no speed
problems, so I'm investigating the client.  dumping on the client to
/dev/null gives nearly the same performance, so I'm confident that
it's an issue with dump + LVM on the client. [1]

The client is all but idle, not doing compression/encryption, and only
has two PVs in the VG, both of which are fast SATA disks.  If I
increase the blocksize of dump to 64kiB (the largest the manpage says
is smart), performance gets better, in the range of 15-20M/s.

Has anyone seen performance this bad from dump before?  Is there
some tunable to get things running a little faster?  24 hours of a
full backup seems just terrible....


[1] - So yea, technically this the wrong place to ask, the LVM mailing
lists seem to be all but completely dead.  On the other hand, lots of
people know stuff about dump here!

-- 
Ross Vandegrift
ross AT kallisti DOT us

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
        --St. Augustine, De Genesi ad Litteram, Book II, xviii, 37