Hi,
Some people here have been evaluating a DLT 2000 drive for doing standard
unix dumps. As compared to an Exabyte 8505 they're getting quite a
performance increase. They can achieve ~60 MB per minute sustained
transfer rates to the drive. The drive is rated at a max of 1.25 MB/sec
and so a 1 MB/sec transfer rate like this seems appropriate. They had
gotten some lower rates at first and then found that by bumping up the
block size option to dump they could achieve the above rates.
On the same machine, using the same two drives, I can't get anywhere
near that performance using afs backup/butc. I'm seeing around 10 MB
per minute on both the DLT 2000 and on the Exabyte 8505. I can't see
any option that would let me bump up the block size in a similar manner,
if indeed that's what I need to be able to do to get better sustained rates.
I *can* hear the drive starting and stopping all the time when the afs
backup is running, so I know it's not streaming like it should be.
I saw a posting last January that mentioned changing some parameters
in the kernel configuration under Solaris 2.4, but not all of those
options seemed to map to older SunOS 4.1.3 defines. Does anyone have
any good experiences getting these drives to perform at rated speeds
and wisdom that they could pass along? The machine in question and
the servers I'm dumping from are on an fddi ring and given that the
unix dumps can get higher rates than I'm seeing it doesn't seem to be
strictly a hardware issue.
Thanks,
Steve Mattson
University of Michigan - CAEN
