Hi there,
On Tue, Jan 05, 2010 at 07:30:44PM +0100, Tino Schwarze wrote:
> > > It looks like btape is not happy.
> > >
> > > Error reading block: ERR=block.c:1008 Read zero bytes at 326:0 on device
> > > "Superloader-Drive" (/dev/nst0).
> > >
> > > Are your tapes old (still good)? Did you clean the drive? Latest Firmware?
>
> The drive requested cleaning just yesterday which I did. I'm not sure
> how old the tape in question really is. I used a dell update utility and
> it updated the drive to v2181 which seems to be the latest for a
> half-height SCSI tape drive. 30MB/s seems a bit low to me - it should be
> able to do 60MB/s per spec. Or is that just theory vs. real world?
>
> > I would add are you using LTO3 tapes or LTO2 tapes?
>
> They are labelled 400GB/800GB - all of the same kind, so they're
> definitely LTO3. The autoloader says: "Drive Idle Gen 3 Data" in it's web
> interface, so yes, I'm sure.
>
> I could check a very new tape tomorrow or try a shiny new one, just to
> be sure.
Here are the results for a shiny new tape with block size 512k:
> Wrote blk_block=750000, dev_blk_num=651 VolBytes=391,110,459,392 rate=59638.7
> KB/s
> 06-Jan 13:50 btape JobId 0: End of Volume "TestVolume1" at 397:1147 on device
> "Superloader-Drive" (/dev/nst0). Write of 524288 bytes got -1.
> 06-Jan 13:50 btape JobId 0: Re-read of last block succeeded. btape:
> btape.c:2345 Last block at: 397:1146 this_dev_block_num=1147
> btape: btape.c:2379 End of tape 397:0. VolumeCapacity=391,370,506,240.
> Write rate = 59587.5 KB/s
> Done writing 0 records ...
> Wrote state file last_block_num1=1146 last_block_num2=0
>
>
> 13:50:27 Done filling tape at 397:0. Now beginning re-read of tape ...
> 06-Jan 13:50 btape JobId 0: 3301 Issuing autochanger "loaded? drive 0"
> command.
> 06-Jan 13:50 btape JobId 0: 3302 Autochanger "loaded? drive 0", result is
> Slot 1.
> 06-Jan 13:50 btape JobId 0: 3301 Issuing autochanger "loaded? drive 0"
> command.
> 06-Jan 13:50 btape JobId 0: 3302 Autochanger "loaded? drive 0", result is
> Slot 1.
> 06-Jan 13:50 btape JobId 0: Ready to read from volume "TestVolume1" on device
> "Superloader-Drive" (/dev/nst0).
> Rewinding.
> Reading the first 10000 records from 0:0.
> 10000 records read now at 1:626
> Reposition from 1:626 to 397:1146
> Reading block 1146.
>
> The last block on the tape matches. Test succeeded.
So this looks very promising: 390 GB and I'm also seeing almost 60MB/s.
I will repeat this test using one of the older tapes, then report back.
Is it possible that the low block size of 64k affects tape capacity? It
looks suspicious to me that all tapes "end" at about the same size...
Thanks so far,
Tino.
--
"What we nourish flourishes." - "Was wir nähren erblüht."
www.lichtkreis-chemnitz.de
www.tisc.de
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