Kernel panic in FreeBSD-8.3 from UFS

[Joerg Wunsch]

As Holm Tiffe wrote:

> ..., but the performance is somewhere below
> the basement:
> 
> 0:        0x1a:DLTapeIV(20GB)    variable       81633    IDRC
> 1:        0x1a:DLTapeIV(20GB)    variable       81633    IDRC
> 2:        0x1a:DLTapeIV(20GB)    variable       81633    IDRC
> 3:        0x1a:DLTapeIV(20GB)    variable       81633    IDRC
> ---------------------------------
> Current Driver State: at rest.
> ---------------------------------
> File Number: 0  Record Number: 0        Residual Count 0
> # dd if=/dev/zero of=/dev/sa1 bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 125.909593 secs (5205005 bytes/sec)

I don't think 5 MB/s is a poor value for a DLT-2000.  On a
DLT-8000 (with wide SCSI), I get a little more than 10 MB/s
provided the data source is fast enough.

> It think the DLT drive should be streaming while writing 64K Blocks from
> /dev/zero, shouldn't it? No, it moves back and forward all the time.

Turn off hardware compression, the drive cannot compress your zeros as
fast as you want.

> This thing is reading even slower than writing, the Drive makes pauses of
> almost 10 seconds between the really short runs.

That's indeed poor.

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)