[5022] in linux-scsi channel archive
Re: Q: DLT7000 tapedrives under Linux
daemon@ATHENA.MIT.EDU (Pieter Krul)
Wed Oct 28 21:40:43 1998
Date: Thu, 29 Oct 1998 00:04:21 +0100
From: Pieter Krul <pkrul@dare.demon.nl>
To: Richard Fish <rjf@estinc.com>, Jon Lewis <jlewis@inorganic5.fdt.net>
CC: Linux SCSI <linux-scsi@vger.rutgers.edu>
Richard Fish wrote:
>
> Jon Lewis wrote:
> >
> > On Tue, 27 Oct 1998, Pieter Krul wrote:
> >
> > > The DLT7000 drives as I know them are able to write data in
> > > so called 'streaming mode' at about 5MB/s uncompressed.
[snip]
>
> > With the really fast tape drives, the problem is usually that you can't
> > give them the data fast enough for them to keep streaming. There is a
>
> Absolutely! one other thing you should do is time test a backup to
> /dev/null. A couple of examples:
[snip]
>
> Your throughput should be at least twice as fast as the rated speed of
> the tape drive, i.e, at least 10Mb/sec -- more if you want to use the
> hardware compression on the drive. Otherwise, buffering may help a
> little, but you'll never get anywhere near the rated speed of the
> drive...
Hi there,
Thanks for your replies, you made me realize that the term `bash` can be
used on my own head.
Since I used IDE/UDMA drives, I assumed they'd provide a throughput
which could be descently used for this ... but forget it.
I did a plain `tar` on /usr to /dev/null, and it turns out that
the throughput was 3.2 Mb/s
Take your 'at least twice' and it all figures out.
Let me get some useful disks and play with some buffering first before
I get back to this issue :-).
Thanks for your time.
Kind regards,
Pieter Krul
--
This machine runs Linux 2.0.36 on a Pentium II (Deschutes).
It has 256844 kB memory, and was down for backups from
10:01 am to 10:02 am last Saturday. It said "PURGE COMPL ".
Is it necessary to reboot now and if so, how can this be done ?
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