We've been using the DLT2000 on Solaris boxes to do desktop backups of PCs,
Macs and UNIX. So far, we've been very happy with they're performance and plan
to also use these for DFS backups of our DCE environment.
I kicked off an fms command to discover the tape length and EOF marker, but its
taking a LONG time to complete. With the drives start/stop frequency during
this test, it appears that DFS is writing very small chunks rather then large
chunks which is what makes the DLTs happy. Is this changable under AFS/DFS?
Did you do something similar under AFS to get the tape media configuration?
The only other thing I could suggest checking into is the kernel configuration
for the DLTs but it sounds like you've already looked into that.
Jack Moore
Pacific Northwest Laboratories
([EMAIL PROTECTED])
On Aug 18, 11:04am, Steve Mattson wrote:
> Subject: DLT drive performance on SunOS 4.1.3 afs backups?
> 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
>-- End of excerpt from Steve Mattson
