Disconnecting and reconnecting an external ultrium tape drive on the fly

[Yogeeraj_1]

Hello experts!

I have one Ultrium external tape drive (Ultrium 1-SCSI) and 2 Rp5430 servers. unfortunately, the Ultrium drive can be connected to only one of the servers at a time.

I am currently using OMNIBACK to backup my data on both servers and this is working VERY Fine!

However, i need also to update my make_recovery tapes regularly for both servers. Previously, i did a shutdown of both servers to disconnect the drive from one RP5430 and reconnect it the other one for the backup. This is no longer possible.

I want to know:

a. Is it safe to on-the-fly disconnect the drive from one server and reconnect it to the other? (of course, switching off the tape drive first!)

b. Can i use PIPES to create a reliable MAKE_RECOVERY tape?
mknod /dev/rmt/0mn p
dd if=/dev/rmt/0m | remsh server2 dd of=/dev/rmt/0mn &
make_recovery_tape -x inc_entire=vg00 -l -v -a /dev/rmt/0mn

Your expert guidance will be most appreciated.


Best regards
Yogeeraj

[Steven E. Protter]

a. Its safe by hard on the parts. The connectors are delicate. I had to replace a connector while I was installing the three we bought.

b. Not sure, but you are better off setting up an Ignite server with a large filesystem and running make_net_recovery to that fs. The restore process has another step, but less wear and tear.

SEP

[Ken Hubnik_2]

I have done it before and just run an ioscan after each switch and it gets claimed. I am sure HP will recommend you power the server down.

[Pete Randall]

Yogeeraj,

Second question first: I don't think so.

First question: If there is nothing else on the bus and you're absolutely sure there's no activity on that channel, it should work, but there is a small chance that there may be problems with the card or the drive. It's your decision whether you're comfortable taking on that small risk or not. I've done it many times.


Pete

[Stefan Farrelly]

We do this all the time without problems. As long as you have pretty much uptodate patches then its fine and perfectly safe. Weve been doing it a lot this last week on production servers and never had a problem.

[Bill Douglass]

From my experience with N-class and L-class machines, it should be safe to do. One gotcha to watch out for is any monitoring daemons that might be checking on the tape drive. Make sure EMS is not mon monitoring the tape drive status on the hosting machine. If it is, you could get numerous errors logged, and possibly cause the dm_stape daemon to start running wild.

[Bruno Vidal]

Hi,
For a.: not it is not reliable, the only thing you will obtain is to destroy the connector, or the card itself (it can work one times but certainly not for ever).

For b.: i didn't try but I think that it will fail, because ignite is using make_medialif to create bootable part on the tape. And for block size for boot record is 2k, so your pipe will completly mixed this, because it is 8k block. It can be working, you must test it.

Now for your problem, I think it would be a good idea to use the server with the tape as ignite server, and you can do your system backup by using make_net_recovery. You can safely recover after by using network (and it is rather quick, I tested it on 100BT and it takes less than 20minutes.

Cheers.

[Enrico P.]

Hi,
HP recommended not switch scsi without shutdown the server.
I some time does it with success but it is not recommended.
For the second question I don' t know but you can use the make_net_recovery with an Ignite server.

Enrico.

[Yogeeraj_1]

Dear all,

thank you for "flooding" me with your precious responses! I really appreciate your feedbacks.

For a.
=======
I WILL NOT DO IT!

For b.
=======
About Ignite Server, will it be wise to setup an Ignite Server in this setup where i have only 2 servers?

If yes, where should it be?
a. On the server where i have the Ultrium drive
b. On the server with no Ultrium Drive?

a or b?

I am running HP-UX 11.11 and have the following installed:
# swlist -l product|grep -i "ignite"
Ignite-UX B.3.6.82 HP-UX System Installation Services

Do i need to upgrade my Ignite software? Any recommended patches?

(the problem is that i have already carried out the recovery process, using the MAKE_RECOVERY tape, in the past on another site where i had an RP5430 "available". I am not sure if i will be able to do it again there. I don't want to take any chances by upgrading my current software)

Again thank you for your precious time and more valuable inputs.

best regards
Yogeeraj

[Bruno Vidal]

Hi,
I think you should put the ignite server on the same server than the ultrium, because I espect you will backup the images of your servers on tapes. You can also create bootable tapes from a network image. Take a look athis really good doc:
/opt/ignite/share/doc/makenetrec.txt

Now, your ignite version is fine, but you can still upgrade it to latest (4.X), it can be done online, without loosing old images already done.

Cheers.

[Yogeeraj_1]

closing thread