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

Eyal Lebedinsky eyal at eyal.emu.id.au
Thu Aug 13 02:15:58 MDT 2009


Hopefully you use 'buffer' to pipe the output of tar to the tape?
Or is modern tar already do this for you?

I also used a reasonably large block size. Tar defaults to a blocking
of 20 (10KB blocks i/o).

When I used tapes at home this made a huge difference as the tape
was *never* streaming without 'buffer'. You also get large IRGs
which leads to bad tape utilization (lower than spec capacity).

The LTO-4 drive can write at a good speed (120MB/s raw) so it should
not be the bottleneck most of the time.

Flat out it should fill a tape in about two hours.


Chris Smart wrote:
> 2009/8/13 Roppola, Antti - BRS <Antti.Roppola at daff.gov.au>:
>> On our Exabyte drives, the compression settings showed up as devices (on
>> Solaris anyway).
>> So something like....
>>  tar cvf /dev/nrst7
> Thanks Antti. Someone else suggested this offline, however Linux only
> offers two devices AFAIK, rewinding and non-rewinding.
> Nevermind, I'm just doing standard old tar across multiple LTO-3
> tapes.. sure isn't fast. Wrote one tape last night and has been going
> on the second since 8am!
> -c

Eyal Lebedinsky	(eyal at eyal.emu.id.au)

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