DLT 4000 Performance

DLT 4000 Performance

Post by Norbert Rollbuehl » Tue, 19 Nov 1996 04:00:00



Hello Everybody,

we have installed a Quantum DLT 4000 FW/Differential tape drive
(delivered by HP) at a HSC-Bus on a K400 with HP-UX 10.10. We expected to
have a data transmission rate of about 3 MB/s, assuming a compresssion
rate of 1:2. Instead we have measured a rate of only 1.28 MB/s at a
compression rate of 1:3 (1 GB saved in 13 minutes). This is indeed less
than the rate we would expect without compression! We think our hard
disks should be fast enough.

Has anybody got experience with this configuration?
Which tape driver is suited best?
What is the correct position of the parity switch at the DLT 4000?

Thank you very much,
Norbert Rollbuehler

 
 
 

DLT 4000 Performance

Post by Hallvard Pauls » Sat, 23 Nov 1996 04:00:00


   Has anybody got experience with this configuration?
   Which tape driver is suited best?
   What is the correct position of the parity switch at the DLT 4000?

I just know that we get about 90-110 MB/min with
our DLT 2000xt on a single ended SCSI. The discs
are on a differiential FW SCSI on the same computer.

--

Hallvard P

 
 
 

DLT 4000 Performance

Post by osse.. » Wed, 27 Nov 1996 04:00:00


Norbert Writes:

: Subject: DLT 4000 Performance

:we have installed a Quantum DLT 4000 FW/Differential tape drive
:(delivered by HP) at a HSC-Bus on a K400 with HP-UX 10.10. We expected to

:have a data transmission rate of about 3 MB/s, assuming a compresssion
:rate of 1:2. Instead we have measured a rate of only 1.28 MB/s at a
:compression rate of 1:3 (1 GB saved in 13 minutes). This is indeed less
:than the rate we would expect without compression! We think our hard
: disks should be fast enough.

:Has anybody got experience with this configuration?
:Which tape driver is suited best?
:What is the correct position of the parity switch at the DLT 4000?

We are running on a D350 doing backups with a product called OpenVision
which in our experience is pretty quick. We are getting about what you are
for backing up D to D which is pretty realistic in the real world. If you
are able to save 4.5 gig of uncompressed date in a hour then you are doing
quite well in my opinion. Compression of 1:3 is better than we see.  

Bob Kirkman
Open Systems Services

 
 
 

DLT 4000 Performance

Post by Darrell Sno » Wed, 27 Nov 1996 04:00:00



> Norbert Writes:

> : Subject: DLT 4000 Performance

> I have 4 DLT-4000 devices on a single HP-PB SE SCSI card. With Omniback II I get around

1.4 MB/s throughput with simultaneous backups to all drives.

Some other test I have performed with dd and a single drive I did get closer to 1.5
MB/s. This is the maximum the drive and controller will support based on the
specifications.

I haven't checked the compression ratio. Hardware compression on the drive is enabled.

--
------------------------------------------------------

Darrell Snow                    Fax:    (206) 682-1041  
Life is too short to drink bad coffee.

 
 
 

DLT 4000 Performance

Post by Jeff Goldstei » Wed, 27 Nov 1996 04:00:00



> Norbert Writes:

> : Subject: DLT 4000 Performance

> :we have installed a Quantum DLT 4000 FW/Differential tape drive
> :(delivered by HP) at a HSC-Bus on a K400 with HP-UX 10.10. We expected to

> :have a data transmission rate of about 3 MB/s, assuming a compresssion
> :rate of 1:2. Instead we have measured a rate of only 1.28 MB/s at a
> :compression rate of 1:3 (1 GB saved in 13 minutes). This is indeed less
> :than the rate we would expect without compression! We think our hard
> : disks should be fast enough.

> :Has anybody got experience with this configuration?
> :Which tape driver is suited best?
> :What is the correct position of the parity switch at the DLT 4000?

> We are running on a D350 doing backups with a product called OpenVision
> which in our experience is pretty quick. We are getting about what you are
> for backing up D to D which is pretty realistic in the real world. If you
> are able to save 4.5 gig of uncompressed date in a hour then you are doing
> quite well in my opinion. Compression of 1:3 is better than we see.

> Bob Kirkman
> Open Systems Services

I hate to jump in here, as this is a little bit off the subject, but we
were told by HP that only their single-ended SCSI controller would
support a DLT tape drive - now I'm reading that someone's got a DLT
attached to a F/W differential controller.

Anyone got any ideas as to what works, and why?
--
Jeff Goldstein
Eaton Corporation

"ALPO costs 99 cents a can.  That's over SEVEN dog dollars!!"

 
 
 

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