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This is a long message.
I recently installed arkeia light on a small server with a seagate
travan ns20 drive (ATAPI version). I did a lot of hunting, looking
for clues as to how to get this drive working correctly. As I never
found any single resource that describes how to do it, I thought I'd
write a summary to help others in the same boat.
There are a few problems using this drive.
(1) First, you of course must use SCSI emulation to get Arkeia to even
talk to the drive. So, make sure that the ide-scsi module is loaded
(if not compiled into the kernel), and that scsi emulation is
activated. On recent Redhat distributions, for instance, doing the
following will suffice:
* Add "hdX=ide-scsi" to the kernel boot paramaters, where X is the
identifier of the ide tape drive (X=d on my system). For instance,
on my system, grub.conf contains
...
kernel /vmlinuz-2.4.20-20.9 ro root=LABEL=/ hdd=ide-scsi
* Add the line
/sbin/modprobe ide-scsi
to /etc/rc.d/rc.local, if ide-scsi is compiled as a module.
(2) Using this drive with SCSI emulation causes tons of sense errors
to clog your log files. Setting the "no block limits" flag
for the drive quiets these warnings.
* Add the line
/bin/mt -f /dev/st0 stsetoptions no-blklimits scsi2logical
to rc.local after the modprobe line to set this flag, and to also
set the scsi2logical flag. Frankly, I don't know whether s2l is
required --- I tested it early on, and have not had any problems
with it, so I left it there. YMMV.
(3) As the Arkeia docs warn, this drive is VERY slow for restores when
coupled with Arkeia; it seems to be slow because seeking to the right
location on the drive takes forever. It is so slow, in fact, that the
drive will often time out before it finds the right spot. This
happens on backups when they are appended to a tape, too, and causes
Arkeia to abort and mark the drive full. Lots of people report this bug
on this mailing list.
I have found no way to make these seeks go faster. My best solution
is to set the timeouts for the device to obscenely high values, and
then exercise a good bit of patience.
* Add the lines
/bin/mt -f /dev/st0 sttimeout 14400
/bin/mt -f /dev/st0 stlongtimeout 28800
to set the timeouts to extremely high values. I've had seeks to
the middle of a tape take 2 hours...
(4) I created a tapetype for the TR5 tapes in
.../server/dbase/f3tape/tptypes.lst
since there didn't seem to be one that corresponded to this tape
format. In doing so, I'm presuming that the capacity is actual
capacity, not marketing fiction.
* Add
ITEM {
"NAME" "QIC 10GB"
"CAPACITY" "10000"
"THROUGHPUT" "1500"
"MAXUSE" "300"
"SIZESEG" "270000"
"COMMENT" "QIC 10GB"
"FORM_FACTOR" "QIC"
}
to tptypes.lst. Note that the other 3 values are guesses, but I am
getting reliable backups and restores with them. YMMV. Choose
this as your tape type when configuring your hardware in xarkeia.
(5) After reading (somewhere) that these tapes/drives were only
reliable in fixed block mode, I made my own drive type in
.../server/dbase/f3drv/drvtypes.lst
that fixed the block size at 512 bytes, which is what mt reports.
* Add
ITEM {
"NAME" "NEW_QIC"
"FORM_FACTOR" "QIC"
"TIME_BEFORE_CLEAN" "40"
"SET_BLKSIZE" "512"
}
to drvtypes.lst. Choose this as your drive type when configuring
your hardware in xarkeia.
If anyone has suggestions about alternative values in the tape or drive
definitions, I'd be interested.
... and that's it! These steps have provided me with what for all the
world appears to be a working and reliable (if slow) backup system;
heck, even restores work! :-)
Cheers,
Ken
--
Ken Yarnall
Dept. of Mathematical Sciences Lebanon Valley College
Assoc. Professor of Math and CS (717)867-6085 yarnall@lvc.edu
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