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

Daniel Pittman daniel at rimspace.net
Thu Aug 13 02:01:05 MDT 2009

Chris Smart <mail at christophersmart.com> writes:
> 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!

Ah.  You used too small a block size, or you can't feed the streamer so it is
having to stop and start all the time.

You need at least a 64K block size to stream on an LTO2, from my testing, and
better 256K.  With LTO3 improving the streaming speed I would guess that 256
or 512K blocks would be a good strategy.

You also want to make sure you can feed at least 20MB/second to the device,
although that probably varies a bit from vendor to vendor.

✣ Daniel Pittman            ✉ daniel at rimspace.net            ☎ +61 401 155 707
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