Problems with dump/capacity/DLT IV 40-80GB Tape cartridges

[Nathan Vidican]

I am trying to make use of dump to backup several volumes to a DLT IV tape 
drive. I am using a Dell PowerEdge 110T, which contains a single DLT IV 
40/80GB tape drive unit attached to the external connector of an Adaptec 
3940UW pci-scsi host adaptor. The tape drive is at ID 1, the controller at 
ID 0, and there are no other devices attached to this controller. There are 
no apparent hardware related problems, just noting this to keep things on 
track: 
 dmesg | grep sa0 returns the following: 
 
sa0 at ahc1 bus 0 target 1 lun 0 
sa0: <BNCHMARK DLT1 391B> Removable Sequential Access SCSI-2 device 
sa0: 20.000MB/s transfers (10.000MHz, offset 8, 16bit) 
 
Output of 'df' returns the following: 
 
Filesystem    1K-blocks    Used    Avail Capacity  Mounted on 
/dev/aacd0s1a   2064302   64488  1834670     3%    / 
/dev/aacd2s1e  70558134 4227862 60685622     7%    /server 
/dev/aacd0s1f   6132382 1363156  4278636    24%    /usr 
/dev/aacd0s1e   8257742  124818  7472306     2%    /var 
procfs                4       4        0   100%    /proc 
 
The Problem: 
~~~~~~~~~~~~ 
 
When using 'dump -0au -f /dev/sa0 /server' I cannot fit the contents of 
/server (approx 4.2gigs of data) onto a single tape volume. The tape 
inserted is a brand new HP C5141F, (which is a 40/80GB DLT IV cartidge). 
Dump prompts for a new tape to be inserted to complete the operation. I 
assumed this had to do with the '-a' part in the dump command; assuming that 
dump is therefore not (properly) auto-detecting the EOT (end of tape), or 
using the wrong recording density and reaching the end of the tape all too 
quickly. Using 'restore -i' I can indeed read the data written to the tape, 
so it is writting the data... just not properly. 
 
The Question: 
~~~~~~~~~~~~~ 
 
Is anyone out there using similar hardware, or know of the proper arguments 
to pass to dump to make full use of the capacity of these DLT IV cartridges? 
I have checked HP's website, and these particular cartidges list a length of 
557Meters, and a density of 46.8K/80K/96K dependant upon 40GB/70GB/80GB 
compression schemes. How do I formulate the dump command to properly make 
use of these tapes.... any suggestions? 
 
-- 
Nathan Vidican 
nathan at vidican.com 
Innovative Product Sales 
http://www.InnovativeProductSales.com/