[clug] LTO-4 drive, turn on compression? [SEC=PERSONAL]

[Daniel Pittman]

Chris Smart <mail at christophersmart.com> writes:
> 2009/8/13 Eyal Lebedinsky <eyal at eyal.emu.id.au>:
>
>> The LTO-4 drive can write at a good speed (120MB/s raw) so it should
>> not be the bottleneck most of the time.
>
> I did some tests and with 256k blocks for 85MB/sec write speed, but
> that was with a single large tar file. I think it's something to do
> with the hundreds of thousands of tiny files that make up my 1.5TB ;-)

My psychic powers are weak at the moment: yeah, it probably is the seeking
implied by tiny files, if you are using something like tar to write.

Buffering might help, but it *really* depends on your data rate.  To feed my
LTO-2 drive well I needed a striped set of scratch disks for buffering, as
well as to have a single streaming read from them.


You might find the filesystem native dump mechanism better, in some cases,
than user-space backup solutions, if it is safe to use.  xfsdump is, and I
find it much faster for the "many small files" case.

        Daniel
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