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Can't Change Buffer Size

sgtvampire
Level 2

Hi All,

New to the forums and need help.  Running Netbackup 7.5.0.6 on an HP DL380 G8, dual 8 Core Processors with 24 GB memory.  Attached is an HP MSL2024 G3 library with two Ultrium 3000 LTO 5 drives from HP as well.

Trying to perform all the tweaks and tuning, but when we try to change the SIZE_DATA_BUFFERS file to anything over 64k, we get an error:

 blocksize error Screenshot.png

 

HP Says its an issue with NetBackup.  Has anyone else seen this issue?

1 ACCEPTED SOLUTION

Accepted Solutions

SymTerry
Level 6
Employee Accredited

What OS are you running 7.5 on?

There was another thread, that addressed this same behaviour. Make sure you have the latiest drivers installed. Also refer to TECH78069, It has 2 workarounds that might help as well. 

View solution in original post

4 REPLIES 4

SymTerry
Level 6
Employee Accredited

What OS are you running 7.5 on?

There was another thread, that addressed this same behaviour. Make sure you have the latiest drivers installed. Also refer to TECH78069, It has 2 workarounds that might help as well. 

sgtvampire
Level 2

Sorry forgot to include that.  Running Windows Server 2008 R2.  Have all latest drivers. 

Will_Restore
Level 6

Can't see how it could be NetBackup fault; might be controller issue. 

 

https://www-secure.symantec.com/connect/forums/tape-device-index-1-has-maximum-block-size-65536-bytes-buffer-size-262144-cannot-be-used

Attention: Newer 64-bit versions of Windows ignore the MaximumSGList parameter because the Storport driver architecture does not support this parameter. If you are using Windows Server 2003 x64, Windows 7 x64 or Windows Server 2008 (R2) x64 then only Storport drivers are supported and therefore the block size cannot be changed. It will always be the default value of 64k. All 32-bit Windows versions are using SCSIport drivers by default and with SCSIport the MaximumSGList parameter can be changed.

 

 

Marianne
Level 6
Partner    VIP    Accredited Certified

I LOVE how hardware vendors simply blame the backup software!!! Doesn't matter where in the world we are!

NBU is merely reporting the problem...

I agree with above posts - HBA issue.

Some years ago, one of my colleagues found the following while assisting a customer with DR testing:

Check the Windows MaximumSGList setting, it may be set so low that the 
default 64k buffer is not being allowed.
 
This snippet is from a Tivoli/QLogic setup, but the principle is the same. 
 You need to identify the driver name for the SCSI or FC interface you are 
using to find the parameter.
 
<<
Important: If your environment includes an IBM LTO Ultrium tape drive and 
your storage agent will be located on a computer using Windows 2000, you 
must verify and possibly change the host-bus-adapter (HBA) setting. For 
most HBA's this value is located in the MAXIMUMSGLIST registry setting. 
The MAXIMUMSGLIST value on the storage agent must be equal to, or greater 
than HEX 41 (decimal 65) or a data integrity error may occur. To verify or 
change the current registry setting perform the following: 
 
Edit the Registry 
Click HKEY_LOCAL_MACHINE | SYSTEM | CurrentControlSet | Services |(vendor 
HBA name*) | Parameters | Device 
Note:
For (vendor HBA name*) in the previous description, substitute the 
vendor's device name for your environment (for example, for the Qlogic 
2200 and 2300, the name appears as Ql2200 and Ql2300 respectively). If 
your vendor's HBA name does not appear as a registry entry, contact the 
HBA vendor to determine the location of the setting and then verify that 
the setting is correct. 
If the setting's hex value is 41 or higher, verification is complete. 
Close the registry editor, and continue with the storage agent 
installation and configuration procedure. If this value is less than 41, 
change the value to 41 or higher, then save the new registry entry, close 
the registry editor, and continue with the storage agent installation and 
configuration procedure. Make sure that all Windows 2000 storage agents 
located in your LAN-free environment meet this criteria. 
 
You can set any maximum block size between 64 Kbytes and
1 Mbyte. The formula to calculate the proper value for MaximumSGList is:
 
     MaximumSGList = ((Maximum Block Size)/4 Kbytes) +1
 
For 256 Kbytes: 256 Kbytes/4 Kbytes = 64. Add 1 for 65 (decimal) or 
0x41 (hexadecimal). The maximum value allowed for MaximumSGLIst is 255 or 
0xFF. For the particular value of 0xFF, the internal value passed to 
Windows 
is increased to 0x101, allowing support for a full 1 Mbyte transfer. 
 
The system must be rebooted for the new registry setting to be effective.
 
NOTE: For 64-bit systems, the OS page size is 8 Kbytes instead of 4 
Kbytes. 
      Therefore, the maximum transfer size is 2 Mbytes, the formula 
becomes:
 
          MaximumSGList = ((Maximum Block Size)/8 Kbytes) +1>>
 
>>
 
For an LTO drive you need the block size to be at least 256k if it is 
going to perform.    That requires the setting of this Registry entry to 
be 0x41.
 
BUT, be careful if you have other non-tape devices on the same SCSI bus, 
or another bus on the same driver.  You may need to set a 
value that is per-port.  You do this by making the registry entry have 
Device0, Device1, rather than just Device.