On Tue, 20 Jun 2006, Joshua Baker-LePain wrote:
> On Tue, 20 Jun 2006 at 10:35am, up AT 3 DOT am wrote
>
> > On Mon, 19 Jun 2006, Joshua Baker-LePain wrote:
>
> >> I'd be awfully suspicious that you're running with hardware compression
> >> enabled (quite possibly unbeknownest to you).
> >
> > That doesn't really make sense to me...if that were the case, wouldn't it
> > affect all of the clients? In any case, I manually turn off the hardware
> > compression before every backup. One thing that has me curious is this:
>
> Yes, it would affect all the clients. All the (already) compressed data
> going to tape would be hardware "compressed" by the drive, making it
> expand and take up more tape space. Therefore, even though amanda only
> saw ~25GB go to tape, on tape it took up the whole 35GB. The error you
> got (short write) typically means you hit EOT. That happened on one
> particular client, and so that particular client failed.
>
> I don't have any experience with DLT, but I've heard tell that with some
> drives turning off hardware compression isn't always easy.
>
> >
> > Avg Dump Rate (k/s) 1491.9 1491.9 --
> > Tape Time (hrs:min) 4:00 4:00 0:00
> >
> > That speed looks a bit slow for a DLT7000...closer to what you'd expect
> > from a DLT4000. Is there some kind of timeout at 4 hours?
>
> Not that I'm aware of, and you didn't hit any timeout anyway -- you got a
> short write. Regarding the speed, since you're not running with a
> holding disk, there are all sorts of things that can affect the dump/tape
> rate -- speed from the client disks, network congestion, etc.
>
> I'd start by using amtapetype to test your new drive, both for hardware
> compression and native speed. I'd also look at adding a holding disk to
> your config, if at all possible.
Thanks for the response. Here's what I get with amtapetype:
su-2.05a$ amtapetype -f /dev/nrsa0
Writing 256 Mbyte compresseable data: 92 sec
Writing 256 Mbyte uncompresseable data: 90 sec
Estimated time to write 2 * 1024 Mbyte: 720 sec = 0 h 12 min
wrote 763218 32Kb blocks in 2334 files in 13153 seconds (short write)
It's going through another write at the moment, but I assume "short write"
means it isn't getting full capacity from the tape? Not sure what those
compression stats mean, either...
James Smallacombe PlantageNet, Inc. CEO and Janitor
up AT 3 DOT am http://3.am
=========================================================================
|
