Re: Backup tools too slow for LTO-3

Stefan Jankowski <dave.null@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
wrote in news:wwey7x75m5a.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx:

Remember the days when the tape drive was the primary I/O
bottleneck in backup operations? Well those days are gone: with
that shiny new HP Ultrium 3 attached to my trusty V240[1] the
limiting factor seem to be filesystem read rather than tape
write operations.

The Ultrium 3 drive needs at least 27 MB/s to be able to stream
(times the effective compression factor that is). The 3510 RAID
as such is able to deliver data at a sufficient rate, provided it
can be read in large chunks, as the following table shows
[ snip ]
However, none of the onboard backup tools (or common
replacements) appears to be able to deliver a sufficient
/sustained/ transfer rate. I have tried:
[ snip ]
Are there any other optimizations, tweaks, tools that I've
overlooked?

I don't think so. I've got a similar setup (3510FC hanging off two
V490s) and opened a few support calls with Sun over this one, with no
satisfaction. Sun doesn't seem interested in making tar, ufsdump, and
fssnap_ufs work any better in this setup. Try backing up a snapshot to
see tape-write performance tank even more.

Should I look at commercial backup software?

I keep meaning to try a few of Sun's offerings (I think at least one of
them is free, but can't remember its name right now).

How do other users of LTO-3 drives do it?

I'd like to know also. Sun tried to tell me that people don't use
ufsdump or tar to backup large systems, but I disagree.

Thank you,
Stefan

Sorry for the commiseration rather than help.

....Steve

--
Steve van der Burg
Technical Analyst, Information Services
London Health Sciences Centre
London, Ontario, Canada
Email: steve.vanderburg@xxxxxxxxxx
.