Very Computer

Hi folks,

We're looking at a Quantum DLT 4500 (DLT drive with a five-tape
autoloader) to hang off a Linux box, for backups on a bunch of UN*X
machines here.  I know that a regular DLT drive will work, but the
vendor wasn't sure that drivers for the autoloader exist for Linux.

Does anyone have insight into whether a Quantum 4500 will exist
happily on a Linux box?  Have you done this?  Was there anything
special you needed to do?

We're running Red Hat 5.0, Linux kernel 2.0.32.  The SCSI card is an
Adaptec 2940 Fast SCSI.

Thanks,
--
Dave Guertin

        mt -f /dev/whatever rewoffl

will rewind the current DLT, offline it, and switch to the next in the
stack. If the current DLT is already the last one then it will just
rewind and offline it.

To do this in C code we used (for Solaris) the mtio(7) api. I can't
find this documented on my Linux system but if you get the source for
GNU's `mt' it should be pretty obvious how to write custom code (this
is what I did to figure out how to talk to the DLTs on Solaris).

Unfortunately, all this lets you do is advance the DLT stack. This is
enough for us, but maybe not for you. To random access a DLT in the
A.L.'s stack as well as doing the claimed 45 sec random access of data
on a particular DLT you DO need special drivers. This I have no
information on, but am interested in (for Linux as well as other
`nix). Anyone?

But for straight dump/read to/from DLT1 then DLT2 then DLT3 ....  No
problem.

-Brett.

Regards,
--
Eberhard Burr    check http://www.veryComputer.com/~Eberhard.Burr/publickey.asc
                 for PGP Key -- #include <stddisc.h> -- electric cookie follows
Q:      How many Marxists does it take to*in a lightbulb?
A:      None:  The lightbulb contains the seeds of its own revolution.

See www.dandelion.com/linux for mtx utility.  We use it on a seagate dat
changer along with amanda for backups.  It is mt modified to work with
changers and seems quite nice.
Chuck

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You might want to check out Arkeia from knox software.  It's not an
inexpensive solutions, but it can fully support most any autoloader.

        Good Luck

                Dan

: Hi folks,

: We're looking at a Quantum DLT 4500 (DLT drive with a five-tape
: autoloader) to hang off a Linux box, for backups on a bunch of UN*X
: machines here.  I know that a regular DLT drive will work, but the
: vendor wasn't sure that drivers for the autoloader exist for Linux.

: Does anyone have insight into whether a Quantum 4500 will exist
: happily on a Linux box?  Have you done this?  Was there anything
: special you needed to do?

: We're running Red Hat 5.0, Linux kernel 2.0.32.  The SCSI card is an
: Adaptec 2940 Fast SCSI.

: Thanks,
: --
: Dave Guertin

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We have a Quantum DLT 4000 running off a linux box (Redhat 5.0);
it is backing up a small network of Solaris boxes.

The biggest problem with DLT's on linux / PC hardware is supplying
sufficient data to the drive for it to "stream". I'm currently
running the full version of BRU, using double-buffering, with
2 DPT SmartCache IV scsi cards, one for the system hard drive,
one for the tape drive (a DLT 4000 is the single tape version
of the 4500), on a 133 mhz AMD clone with 64 mb RAM.

What happens is that the software dumps data over the network
into a buffer, and when the buffer is full, dumps the buffer
to tape. In our case, the network speeds are about 1/4 that of
the DLT, so the tape only records 15 sec. out of every 2 min.

Interestingly enough, if I attach a 4mm DDS2 to the exact
same setup, it streams (continously writes) to the tape
drive, though the total backup of about 40 gb takes a bit
longer than with the DLT.

Stephen