14 May
2007
14 May
'07
8:04 a.m.
On Sun, 13 May 2007 21:39:00 -0500
Jim Leonard <trixter at oldskool.org> wrote:
My concern is that it takes nearly two hours to fill a
DLT IV (35GB)
tape, regardless of which drive I use or HBA settings I configure.
The Quantum drive averages 4168 kB/s; the SUN drive is slower and
averages 3355 kB/s. Are these times normal?
That speed seems quite reasonible. I
think you can now get an impression
why "modern" file systems have a snapshoot function to assist long
backup runs.
With such large capacities per tape, I would have
assumed they could
be filled faster... They are reporting a 10MB/s speed, why am I
getting only 4MB/s?
Don't confuse interface speed vs. actual media speed.
Another question: Is it normal for DLT drives to go
faster if
compression is disabled?
Maybe. If compression is enabled it can swallow more data.
Your computer
has to deliver this data. Your backup programm and disks my not be able
to stream enough data to the drive to keep the drive bussy when
compression is enabled. This resuls in sawing the tape back and forth.
Somthing that will drop the over all data rate dramaticaly and stress
the tape as well as the tape drive.
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/