Using multiple tape drives

[Alon Jacob]

On one of my servers we're backing-up into two different tapes, and in order to save time I'm running two batch jobs at the same time to do so. The only problem is that I have to devide the files and folders "manualy" between the two.
My question is - can I use both tape to work simultaneously (not one after the other) in a single BACKUP command, and i so - how?

[Kris Clippeleyr]

Alon,


can I use both tape to work simultaneously


I'm afraid you can't. The backup operation to tape can use multiple tape units, but only one after the other.

Regards,

Kris (aka Qkcl)

[Alon Jacob]

Kris.

Just to be sure I explained myself well - I need to use 2 different DRIVES at the same time.

Alon.

[Bojan Nemec]

Alon,

As Kris mentioned, you can not use 2 different tapes simultaneously in one single backup command. How will backup know what to write on each tape?
Maybe a stupid question, but if you have more than one disk to backup, you can "divide" backups by groups of disks.

Bojan

[Robert Gezelter · Accepted solution]

Alon,

Your first question was clear.

BACKUP uses one drive, then the other.

If you can break your backup into two separate streams, you can run two BACKUP processes at the same time, and obviously use both tapes. I frequently do this to make BACKUP sets more manageable, and to allow different backup policies for different groups of users.

- Bob Gezelter, http://www.rlgsc.com

[Antoniov.]

Alon,
I believe you still continue divide manually all files and directories.
I don't know what hardware you have and am not sure two tapes work always faster than single tape, for example DLT unit.

Antonio Vigliotti

[Kris Clippeleyr]

Alon,

With "tape units", I meant different tape drives. And as Bojan said, you cannot use two tape drives in one BACKUP command simultaneously. What is possible, is to use two or more tape drives in a serial manner, like:
BACKUP/IMAGE DISK1 MKA0:DISK1.BCK/SAVE,MKA100:
then if the tape in MKA0 is full it will overflow to the tape in MKA100:.
I know that this is not what you want.
The best thing to do for you is to create 2 backup jobs (one for 1st tape drive; another for the 2nd), and split the files/directories among them, and then launch them at the same time.

Regards,
Kris (aka Qkcl)

[Jan van den Ende]

Alon,

Something more-or-less in line with how I understand your question:
What you COULD do is provide the pool of your Backup processes with a single file of 'things to do'. The processes will have to know what goes into a saveset.
Your backups will somehow have to deliver a number of savesets.
The moment a process is about to begin a saveset, the name of that saveset is written to a 'semaphore' file (or, better, is created as a directory in a semaphore directory, which delegates the desired locking to RMS).
A backup process about to start its next saveset tries to create the semaphore. If successful, do that saveset, if unsuccessfull, proceed to next saveset, until 'things-to-do' exhausted.

One drawback: now you need VERY good administration of WHICH saveset is on WHICH tape!

Hope this helps

Proost.

Have one on me (and another one because it's my birthday!)

Jan

[Mobeen_1]

Alon,
The answer to your question is NO.
I am afraid the BACKUP command is not intelligent enough to do this...i know this would be good to have...Many Enterprise Backup Systems using Tape Libraries do this.. but not possible through the BACKUP command.

As many have suggested the only way to do this in the resources you have is by using 2 backups commands..

rgds
Mobeen

[Anton van Ruitenbeek]

Alon,

As many people before me: It's not possible to use simultanius in one backup command more then 1 tapeunit. As Mobeen statet: Many enterprice backup solutions can do this. But the biggest problem of this: If you are using an enterprice backup solution: The software must be installed before restore. And the version is also applicatble. With all the VMS backup's you are free to restore on any system, and the major and importance of VMS-backup: You can restore on a clean system and after this 'reboot and youre up'. The only problem you have with VMS backup is: 'Where is the tape (or tapes) to restore!'. With all the enterprice softwares is: 'Where is the index, use it, then we know whitch tape must be used, then we can start restore and you can go on !' This is why most enterprice backup solutions always backup the index of all the backups on top of every tape. So if you use any backup solution other then VMS-backup, the software must be installed and running before you can use it !
The solution of Jan would be nice, and should work alright. But as he stated 'Make sure youre administration is alright otherwise you better can not backup, so you dont have to restore'

AvR

[Lawrence Czlapinski]

Alon, We run backups to two different tape drives on two of our clusters.
No you can't use two tape drives from a single BACKUP command.
The way to do it with VMS BACKUP is to have two (or more) backup jobs, each with a lists of unique disks to back up. Each of our backups has a default tape drive to run on. If a tape drive is down, the second backup job can be run on another tape drive.

[Alon Jacob]

Thanks all.

As I understand it's realy impossible to use both drives from a single backup command, justas I thought.

Thread closed.

[Ian Miller.]

Alon, to thank the people who have helped you see
http://forums1.itrc.hp.com/service/forums/helptips.do?#33

[Alon Jacob]

But of-course I will... ;-)
Anyway - thread is closed as far as I see it.

[Alon Jacob]

Got the answer I needed.

Thanks all.