Arno Lehmann wrote:
Hi,
On 9/25/2006 8:31 PM, Hristo Benev wrote:
Hi,
I have Python 04106-XXX Rev: 7550 DDS-3 tape drive.
Is there a way to check if HW compression is ON or OFF, and what is
better to use HW or SW one currently I use GZIP=1 SW one
Well, Hardware compression is done in the tape hardware. You transfer
the uncompressed data through your network and backup server and SCSI
subsystem, but don't need extra CPU power on the client.
Personally, I prefer hardware compression, but there are claims that you
might lose the whole tape contents when you encounter incompatible
devices. Which is something I consider a myth, given that
hardware-compressing tape drives are always compatible (as far as I know).
Trying to compress pre-compressed or encrypted data is
counterproductive, so, if you need fine-grained control over compression
you better use software compression.
I'm aware of all this, but in my case I think SW compression is better,
because I have 10MB network between servers (and that is enough for my
setup - except backup there is no high bandwidth demand application).
Also I've tested the HW compression (on similar drive in 1999) and the
backup was much slower??? and compression really bad!!!
Thats why I typed the command that should disable compression, but how
I can check???
mt -f /dev/tape compression off
tapeinfo gives me an error
tapeinfo -f /dev/tape
Try tapeinfo -f /dev/sgX
tapeinfo needs to be pointed to the generig SCSI device representing
your tape drive.
Arno
I have st0 as device, but it gives me the same result
mtx: Request Sense: Long Report=yes
mtx: Request Sense: Valid Residual=no
mtx: Request Sense: Error Code=0 (Unknown?!)
mtx: Request Sense: Sense Key=Hardware Error
mtx: Request Sense: FileMark=no
mtx: Request Sense: EOM=no
mtx: Request Sense: ILI=no
mtx: Request Sense: Additional Sense Code = C1
mtx: Request Sense: Additional Sense Qualifier = 85
mtx: Request Sense: BPV=yes
mtx: Request Sense: Error in CDB=no
mtx: Request Sense: SKSV=no
mtx: Request Sense: Field Pointer = 00 00
INQUIRY Command Failed
and mt status gives:
mt status
SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 512 bytes. Density code 0x25 (DDS-3).
Soft error count since last status=0
General status bits on (41010000):
BOT ONLINE IM_REP_EN
Thank you,
By the way I use RedHat based OS (CentOS 4.4)
Thanks,
--
Hristo Benev
IT Manager
WAVEROAD
Partners in Telecommunications
514-935-2020 x225 T
514-935-1001 F
www.waveroad.ca
[EMAIL PROTECTED]
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