multiple LTO devices in single tape library

Why would you do that? Why not defined them as LTO-2 drives as they are LTO-2 devices? Partitioning tape library is something I would suggest because if you create pool for LTO-2 and then LTO-3 devices it will work fine for backups. For restores pool restrictions are not applied thus what could happen is that LTO-3 volume is loaded into LTO-2 drive and that won't work. By partitioning library into two (one with LTO-3 and one with LTO-2 devices) you don't have worries like that.

You can do that from library only (NetWorker does not partition library, for that you will need AlphaStor). Now it is only a question if your library supports partitioning.

sorry... i was going to define them as LTO-2 drives as i didnt think you had the option not too... :O)
Can you point me to the directions for partitioning... we are currently 7.2.

We're running an environment with different tape drive generations in one library device, too. Networker is able to handle the situation for example by using different pools for each tape generation. You can limit a pool to specified tape devices (at least in NW 7.3).

PLEASE NOTICE: Networker automedia management cannot be used anymore when mixing up tape gererations in one library as you'll sometimes from newer tapes (eg. lto3 tapes) in older drives (eg. lto2 drive). This will result in an error generated by the hardware and Networker is not able to handle this, of course...

I don't partition my library so I defer to Hrvoje Crvelin on that subject. But I have an 7.2.1 environment where I have dedicated certain drives to pools and pools to groups in order to help manage SAN bandwidth utilization during the backup window.

I suggest doing the following:
1. Create the LTO-2 drives in the library.
2. Create the new groups to be written to these new drives
3. Create one or more pools for the new media. In each new pool select the new drives for use by the pool, and select the appropriate group(s) to be written to the new pool.
4. Label tapes into the new pool(s).

This does make it a little more challenging to figure out what is wrong when something isn't working, but it works well for us and has been solid for 3+ years.

I hope this is of help and not too late.

Does the pool restriction work when you do restores? This is one of the things that certainly didn't work in the past and reason why Legato didn't support it.

With NW 7.3.2 it seems to work quite fine. Networker loads tapes from restricted pools only in assiged tape drives when restoring files. I can't tell if this worked in NW 7.2 - which is used by Debra.

Hi Hrvoje,

It has worked for me, both for backup and restore, but I have only tried it on 6.1.3 and 7.2.1.

I wasn't aware that it was not supported. Do you have any more information about that? I am pretty sure I have described this to both a NetWorker consultant and to the NetWorker support folks and had not been told that it was not supported.

Thanks,
Paul

It has been like that for years and document discussing this was available from PartnerNet. It's good to know this has been addressed finally.

Technical bulletin 371, at least the copy I have, states following:

NetWorker Restores and Mixed Media
 
Pools can be used to restrict what device and media type 
the NetWorker software uses for a backup. However, the 
NetWorker software ignores those restrictions for 
restores, because a restore is designed to use the first 
drive it finds. 
 
A restore attempts to load the required cartridge into the
first drive found regardless of the drive type, which 
could lead to unexpected results. Therefore, to perform a 
restore operation with mixed media, the operator must 
manually mount the required cartridges before initiating 
the restore. 

Thanks Hrvoje,
It could be that I have not experienced the restore problems because I have the pools assigned to either a storage node or the server. I should have stated that in the first post. Based on what you have said and the tech bulletin, I'm not sure that we aren't just lucky, and I probably wouldn't recommend using our approach without doing some serious testing. But assigning the special pool and devices to a storage node might be the approach that makes it work.

Paul

I guess the question is should I upgrade to 7.3 (I hear 7.4 is available too). If i use the approach where pools are assigned I thought this would be ok for restoring. LTO-3 is backward compatable so these drives would not be an issue. LTO-3 in an LTO-2 drive would cause problems.
I am also curious about the Networker automedia management not being able to be used anymore . what level of management are we actually losing?

As I'm at 7.2.1 I can't speak for 7.3 or 7.4 other than to say that I am still waiting for that 7.3 release that I am comfortable upgrading to and 7.4 is way too new for my taste.

Setting up one or more pools for the LTO-3 media and assigning those pools to just the LTO-3 drives should work fine for the backups. The question that Hrvoje raised is whether you will have issues when trying to restore from the LTO-3 media since NetWorker may try to mount the tape on an LTO-2 device. The work around, if that happens, is to premount the tape on an LTO-3 device and then start the backup. You will probably want to test this and/or keep close tabs during the first few days/weeks of operation to make sure it is behaving as desired.

Regarding Automedia management, we have it turned off and manually label new tapes into pools. If you have been using this feature and want to keep using it for your LTO-2 media, you would need to manually label your LTO-3 media into the appropriate pool(s). But be aware that if you run out of LTO-3 media for a backup, the library would probably label an available LTO-2 tape into that pool. That may or may not be a bad thing.

Good luck,
Paul

Otmar Meier posted some information regarding Networker release dates on another thread. To summarize it:
- Networker 7.4 will be available at the end of june (it is not yet released but announced)
- Networker 7.3.3 is scheduled for august.

From my point of view you can upgrade to Networker 7.3.2 Jumbo Update 1 without concerns as there are many issues that have already been fixed. Who can guarantee that there won't be any NetWorker 7.4 or 7.3.3 jumbo patches?

Device(s)-to-Pool(s) settings work quite fine with Networker 7.3.2. When Networker loads tapes only the assigned devices are used to mount tapes - for both backup and restore operations. The only situation where you may run into trouble (apart from manually mounting LTO3 tapes in LTO2 drives) is running an inventory or label operation in silent mode. NetWorker is not able to mount specific media types to respective drives.

To answer your question what level of management you'll be losing: Networker will not reuse tapes by itself. This means that you'll have to manually re-label all tapes that have expired. Another big disadvantage of disabled auto media management is NetWorkers ability to recycle tapes from and to other pools. You'll have to make sure that all pools have enough tapes with status appendable. This is more relevant when you're using numerous pools in your configuration.