Block Size issue

[BVshet]

Hi Team,

We use to use SIZE_DATA_BUFFERS a value of 262144 and backups use to work fine.

Now suddenly backups are failing with error "The tape device at index -1 has a maximum block size of 65536 bytes, a buffer size of 262144 cannot be used"

Where can we set block size for a tape drive is there any registry ??

Now when I change the SIZE_DATA_BUFFERS to 65536 backups run in non encrypted volume pool.

However I think the encription key we use is of 256Kand thats why I cant run backups in encryption pool.

Need help ASAP.

Many Thanks.

[mph999]

OK ...

We use to use SIZE_DATA_BUFFERS a value of 262144 and backups use to work fine.

Now suddenly backups are failing with error "The tape device at index -1 has a maximum block size of 65536 bytes, a buffer size of 262144 cannot be used"

So, what has changed, because if it was working it won't suddenly start to fail like this.

Has the HBA been changed/ firmware/ driver, the HBA is a common cause of this error (it is usually the HBA that cannot handle the larger blocksize).

As you have found, the job works with the smaller blocksize, so you ned to find out what has changed, because there is nothing in NBU that can be done to fix this, as it's not NBU that is actually causing the error.

[RiaanBadenhorst]

Hello

What changed? In the old days (2001-2004) we used to set a entry in the registry that enable larger block sizes to be handle by the HBA.

This EMC article touches on the changes required. Basically the MaximumSGlist entry dictates the allowed blocksize.

https://community.emc.com/docs/DOC-32968

This setting applies for most (if not all) HBA's. I used to set it for Qlogic.

[Will_Restore]

May be driver issue.  See this older thread:

https://www-secure.symantec.com/connect/forums/tape-buffer-size-lower-netbackup-configured

[BVshet]

Hi All,

There was battery replacement done on server after that the tape drive went down at NBU level.

I reconfigured it and ran backups then it gave the error.

There was nothing changed from NBU or tape drive perspective.

Its standalone tape drive LTO , apologies forgot to mention that in begining.

We raised call with HP replaced tape drive and scsi card as well still smae issue.

Please advice.

[mph999]

I'd try and write to the drive outside NBU using a 256k block size and see what happens.

Hopefully you are on Unix/ Linux

Use a tape that has no data, and  dd command to write to it.

[Marianne]

The assumption is that the server was rebooted when the battery was replaced?

If you look at the discussion that Will mentioned in his post, you will see that we saw the same thing at our customer after a reboot.
When we looked at the driver details in Windows Device Manager, we found that the Windows driver was loaded.

On 64-bit servers, you need to use the Vendor drivers.

Please use the nt_ttu tool (with a tape loaded in the drive) to see what block size is reported.
See this TN: http://www.symantec.com/docs/TECH22746 

[BVshet · Accepted solution]

Hi All,

Looks like the issue was with the SCSI card we replaced the SCSI card and the backups started running fine.

Many Thanks.

Bshet.