Technical Support: SCSI Tape Drives

I'm writing this more as a commentary on SCSI tape and Linux then anything else. Ok in truth this is to help out a guy on the Red Hat Mailing list who's having problems with SCSI Tape. Here are the posts for further reading:

https://www.redhat.com/archives/redhat-list/2005-June/msg00240.html
https://www.redhat.com/archives/redhat-list/2005-June/msg00263.html
https://www.redhat.com/archives/redhat-list/2005-June/msg00268.html
https://www.redhat.com/archives/redhat-list/2005-June/msg00293.html

The server we dealing with has the following specs:

   - Server: IBM xSeries 236 Server
  - Backup Tape Drive: Qantum DLT VS80 40/80 Tape Drive PN: * 59P6682*
  - SCSI Controller: PCI Ultra 160 Adapter - single channel, LVD
  transceiver, 64-bit PN: *19K4646*
  
  - Enclosure: IBM External Half High SCSI Storage Enclosure PN: *
  3510020*
  - SCSI Cab: IBM 2M External .8mm SCSI Cable PN: *01K8027*
  - *Operating System: * RedHat Enterprise Linux v3.0 U3
  - Raid 5: 5 Hard Disks Connected by ServeRAID-7e for RAID 5

Of the top of my head, I know that IBM turns off all unused SCSI id's. So the first thing to check is that the SCSI ID for the tape drive is enabled in the SCSI cards BIOS. You will want to make sure that the drive is using a ID that is not used by any other ID's.
In an ideal world you do not want the SCSI Tape drive to be used on the same SCSI card as a RAID set up. I have seen multiple problems with this, but the situation isn't always ideal so, I have seen it work as well. YMMV here.
Check that all the appropriate power connections have been made, and boot the server. During the boot process or in dmesg, you should see something like the following:

SCSI subsystem driver Revision: 1.00
scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.36

aic7899: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs

and

Vendor: IBM Model: ULTRIUM-TD2 Rev: 4770
Type: Sequential-Access ANSI SCSI revision: 03
blk: queue f7fd4418, I/O limit 4095Mb (mask 0xffffffff)

In this case, I have an Adaptec AIC7xxx card and an IBM ULTIUM-TD2. This is the firmware reporting to the OS. Hopefully we should also have the following:

Attached scsi tape st0 at scsi0, channel 0, id 1, lun 0

You can double check dmesg with:
dmesg | grep Attached

So, at this point you should have a dev entry in the /dev/ directory for st0
ls -la /dev/st0
Which should show:
crw-rw---- 1 root tape 9, 0 2005-06-13 08:07 /dev/st0

If you do not have the /dev/st0 entry or the Attached message, you should try modprobing the the st module:
modprobe st

The next thing to check is that the device is responding to commands:
mt -f /dev/st0 status
Which show something like:

drive type = Generic SCSI-2 tape
drive status = 318767104
sense key error = 0
residue count = 0
file number = 0
block number = 0
Tape block size 0 bytes. Density code 0x13 (DDS (61000 bpi)).
Soft error count since last status=0
General status bits on (45010000):
BOT WR_PROT ONLINE IM_REP_EN

In this case, everything appears fine. The important part with the drive in the above, is that the block size is reporting 0.

If for some reason the we get errors from the mt, You will want to verify that mt is installed:
rpm -qa | grep mt

If you need to change the the blocksize the command would be:
mt -f /dev/st0 setblk 0

So at this point we should test if the tar command is working with the tape drive:

tar cvf /dev/st0 /etc/hosts

This should backup /etc/hosts to the tape drive. Obviously you will want a tape in the drive. I would say that we also want to make sure that the restore is working:

tar xvf /dev/st0

This should restore the file. So now the question is, in consultant environment, what do you use for backups. There are a number of open source products and free products to use. Here are my recommendations:

Kbackup and Kdat : Both of which have nice GUI's and a nice feel to them. The biggest problem that I see with them, is that there is no networking support. If you want to back up any client machines to this tape, you will need to mount them to the Linux machine using Samba or NFS.
Other options are: Bacula and Amanda. Both of which are really great, but have no GUI's. This is a shame because, in any enviroment you will want to backup all of your clients machines and you will want the customer to be able to use it. If you do not have a user who has much experience in Unix/Linux they are SOL.
Well, that's all I have.

Ubuntu

Ubuntu Rules. I cannot go on about how much I love Ubuntu. It's supported by a small company, it's open source, it's based on Debian. What can I say?

Anyway, I was thinking about saying something to the effect that it would be interesting to combine Kevin Rose's project that is on his site for war driving with the Whoppix disto. Wouldn't that be interesting?

But I clicked on the links at his site. Sure enough, bit torrent is already installed. I love it.

Kevin Rose

So Kevin Rose is leaving the only slightly known show Attack of the Show. So perhaps his new show will be good. You can see it here: http://systm.org/ So take a look.

G4TV - Attack of the Show

I hate Attack of the show. The old TSS was apparently great, but the Show sucks. I cannot stand it. The only reason why I actually watch the channel is because Xplay is amusing.
Morgan West and Adam Sessler (sorry for the spelling) are very funny. They are like friends that I remember throughout the the years if they did game reviews. Generally their reviews are on track and though I don't I play video games very often, I do rent on occasion.
Back to my rant on G4. Christ o mighty does the Channel suck. Icons has a been reduced to repeats galore and everything else pretty much makes me want to gag on a regular basis. The final straw was the change of TSS to AoTS.
I pretty much hang in the tech support forums for some strange reason. I like the crowd. Most of the geeks that hang out are knowledgable but not Uber Geek. Well except Uber Pengium :). Overall it's an enjoyable environment.
Somehow, I feel bad that I post to a forum that supports a major corporation. Why should I give my tech support skills free of charge to this multi million dollar corporation? Aka Comcast. That has just slaughtered this channel? Mainly because if I were some n00b looking for help, and the closest thing to tech that I knew was the old G4. I would post there. Kinda reminds me of the Commodore 64 days. I wish that there was anything like this during that time. I would be a programming nightmare. Unfortunetly there wasn't. And I'm just a Tech Support Geek.

Oh well.

Netware Continued

Ahh the joys of Netware. So I've found the way to mount an NFS server on Netware. I'm investigating the NFS Gateway for Netware 6.5. Seems like it's a joy to use. Not. Now I just have to figure out how to get my cdrom recognized by Netware and I can install this.

What a pain.

Netware and NFS

Darn how I hate Netware. It is the most difficult and terrible thing to use. I have to test a backup agent for Netware. Now it's not bad enough that I have to use Netware but I have to figure out how to mount NFS partitions. Here's my latest post from somewhere else:
------------
I have ruled out the possiblity of loading DOS network drivers and installing a SMB client in DOS to make a drive letter mounted to the SMB server. And then mounting the Driver letter in Netware. Mainly because Netware loads it own drivers for the network card and has it's own tcp/ip stack. I would probably run into alot of problems loading the driver and the stack in two seperate but similiar environments on the same system.

So I have found some documentation and errata on getting an SMB client on Netware. The power of Google is amazing. Just type in what you want. Never would have thought about it. "nfs client for netware"

Which brings back this reference
http://www.ndsengineers.com/archive/index.php/t-63893.html
Which brings us back to Novell:
http://www.novell.com/documentation/nw6p/index.html?page=/documentation/lg/nw6p/native/data/hz8pck9v.html
----------------------

So that brings you up to date on my latest. Hopefully by Monday I'll have more.

Whoppix

Has anyone seen this? Wow how interesting. I'm very big on Knoppix distro's and Linux cd distro's. But this is a complete hacker tool. It's awful the things that you can do with this.

But what I found to be especially bad was the flash demos on exactly how to break into encrypted wireless networks.

Very interesting reading from a security point of view. http://www.whoppix.net

Start O Blog

Yes my friends I have decided start a Blog. Terrible. I hope for this to have some unique perspectives on my life in Technolgy and whatever else.