Upgrade LTO2 to LTO3 Question

[pinchaser]

Netbackup 6.0MP5 Solaris

   I have a StorageTek SL500 Library with 6 x LTO2 drives. I want to upgrade to LTO3 drives. Is there some way to have both LTO2 and LTO3 drives in a robot at the same time and use different media (HCART2 and HCART3) to the appropriate drives?  I believe I have read that there is not some way somewhere... but then I understand the LTO3 tape drives can indeed read/writew LTO2 media. Why in the world would Netbackup not support this option if the hardware does?

Thanks

[Dion]

Hi

This setup shouldn't be a problem.  NetBackup logically groups HCART2 tapes with HCART2 drives and likewise for HCART3.  This is done to prevent incompatible tapes being loaded into the incorrect drives  By running your library with both drive types and media types, NetBackup will only load HCART2 tapes into HCART2 drives and the same with HCART3 (if configured this way).  You will also need to make sure that tape storage units only contain one drive type i.e. you will need at least one HCART2 and a separate HCART3 storage unit for each server (if you are using SSO).  These storage units can be placed into storage unit groups to which your policies can write.  When a backup or restore requires tapes from both media types, it will automatically load the correct type tape into the correct drive type.

The only issue I can think of by running both drive types is when/if you want to optimise your NUMBER_DATA_BUFFERS and SIZE_DATA_BUFFERS settings.  You will have to find a happy medium between the two drive type settings and possibly not use recommendations on only the one drive type.

I'm currently running an IBM TS3500 library with 5 x LTO4 drives and a mixture of LTO3 (from the previous library) and LTO4 tapes.  I configured both tape-types and all drives as HCART tapes and devices.  This way I have both LTO3 and LTO4 tapes being loaded into any of the LTO4 tape devices interchangably.  NetBackup handles this fine - I also write multiple copies of certain backup (e.g. Exchange) of which one is directed to a LTO4 tape and the offsite copy to the LTO3 tape at the same time.  Obvioulsy this is only possible due to the read/write compatibility of LTOx-1 drives.

About testing this configuration, I generally restore over 1TB of Exchange data per month from either the LTO3 or LTO4 copy and haven't had any problems.

One last suggestion... Depending on how many LTO3 drives you are considering buying and what you decide to configure, I would suggest that you keep at least one drive configured as an HCART2.  This will allow you to restore images stored on your configured HCART2 tapes.  If you are replacing all of your LTO2 drives with LTO3 ones you could configure all the new LTO3 stuff as HCART2 then you will not have to worry about this.  The reason that you cannot have both LTO2 and LTO3 drives configured as the same type is that you don't want LTO3 tapes being loaded into the LTO2 drives.

Excuse the long reply - just wanted to be clear on the answer as you don't want this stuff misconfigured.

Hope this helps

Dion

[pinchaser]

Dion,

   Thanks for the information... I have a follow up question:

In your configuration, if both LTO3 and LTO4 tapes are available and an LTO4 tape drive is being used to backup, will the default behavior be to select an LTO4 tape? Or is it a random chance that either could be selected?

[Dion]

I have LTO3 tapes set up in an OFFSITE pool so all offsite backups go to these by default.  The reason for this is that the tapes generally get used less than the LTO4 tapes.  The LTO4 tapes are all configred in the SCRATCH pool - all onsite backup and offsite backups will use this when required.

The other reason that I'm using the LTO3 tapes for offsite mainly is the fact that I eject tapes every day and if I use the LTO4 tapes I get a fairly low % of tape usage during the week when I run Incrementals.  When my Incremental backups grow, I will change this to the LTO4 tapes to prevent too many tapes from being ejected dsily.

Cheers

Dion

[J_H_Is_gone]

"In your configuration, if both LTO3 and LTO4 tapes are available and an LTO4 tape drive is being used to backup, will the default behavior be to select an LTO4 tape? Or is it a random chance that either could be selected?"

you have to look at drive type and media type

( issue is there is no Hcart4 in the software)

if your LTO3 drive is set up as hcart3...

   and your LTO3 tapes go in as hcart3

      it will only pull hcart3 tapes for hcart3 drives.

for my LTO4 drives i set the up as hcart

  i then have my LTO4 tapes go in as hcart

    it will only pull hcart tapes for hcart drives.

so look at your device monitor and see what Drive type you have set.

then go to your media and see what they come in as.  if not correct you need to set up Barcode rules.

[Dion]

Just to add onto the last post...

If both drive types and tape types are configured as, for e.g, HCART, then yes tapes and drives will be used randomly.  NetBackup doesn't care whether it is an LTO3 tape going into an LTO4 drive and visa versa.  This is due to the fact that you have configured NetBackup to see all of them as the "same".

Cheers