Summary
By default, DPX writes in 32 thousand (32 KB) blocks. If your tape drive supports larger block sizes, you can increase the block size used. The benefit is an increase in the performance of your backups.
Resolution
You can increase block size by a multiple of 32 KB. The default multiplier in DPX is 2 and displays in DPX as --blksiz 2. The default tape drive block size is 64 KB.
When you change 2 to a different value, the 32 KB block size is multiplied by the value you enter.
For example, to increase the block size by 8:
On a UNIX device server:
- Open DPX/bin/ssdmbr on the device server.
- For --blksiz, change the value shown to 8: --blksiz 8
The DPX block size of 32 KB is multiplied by 8, making the tape drive block size 256 KB.
On a Windows device server:
- Edit the following string value in the registry on the device server:
HKLM/Software/Syncsort/Agent/SSDMBR
to read:
--blksiz 8
The DPX block size of 32 KB is multiplied by 8, making the tape drive block size 256 KB.
Note: It is important to test different block sizes per the article Verifying Large Blocksize Support on Devices Note: If a DPX labeled tape (volser) was already used with Hardware Encryption, in order to use this tape with the Newly Set blocksize, this tape needs to be re-labeled. It is not required to re-label tape (volser), it is not encrypted or using Software Encryption.