How to enable hardware compression on LTO4 drives?

[tivolimistery]

Hi all,

I would ask you some information about hardware compression.
If possible, I would know how I can verify if hardware compression is enabled on LTO4 drives installed in our IBM TS3584 tape library.

I have to use tape library web interface or can I understand something more using TSM 5.5 Server!?

What do you think about hardware compression!? In your opinion, hardware compression may increase (or decrease) backup performance?

Thank you in advance,
Mauro T.

 

[moon-buddy]

If you issue the command 'q drive f=d' and look for the line/s 'read fromats'/'write formats' and is a 'C' is appended like ULTRIUM4C, then compression is enabled.

If it says like ULTRIUM4C,ULTRIUM4, then the drive can choose between compression and non-compression to fit the data. Normally, it is set to do both and also to read/write on lower LTO formats like LTO3, LTO2:

Example:

Read Formats: ULTRIUM2C,ULTRIUM2,ULTRIUMC,ULTRIUM
Write Formats: ULTRIUM2C,ULTRIUM2,ULTRIUMC,ULTRIUM

 

[tivolimistery]

Thank you very much Moon-Buddy.

Executing 'q drive f=d' command I obtained read and wirte compression options available on our 18 LTO4 drives:

Read Formats: ULTRIUM4C,ULTRIUM4,ULTRIUM3C,ULTRIUM3,ULTRIUM2C,ULTRIUM2
Write Formats: ULTRIUM4C,ULTRIUM4,ULTRIUM3C,ULTRIUM3

If I can I would ask you 2 last information:

- is there a way to force compression of next backed up data (in order to reduce the amount of used tapes)? is it a good idea?
- in your opinion, hardware compression may increase (or decrease) backup performance?

Many thanks,
Mauro

 

[moon-buddy]

Thank you very much Moon-Buddy.

Executing 'q drive f=d' command I obtained read and wirte compression options available on our 18 LTO4 drives:

Read Formats: ULTRIUM4C,ULTRIUM4,ULTRIUM3C,ULTRIUM3,ULTRIUM2C,ULTRIUM2
Write Formats: ULTRIUM4C,ULTRIUM4,ULTRIUM3C,ULTRIUM3

If I can I would ask you 2 last information:

- is there a way to force compression of next backed up data (in order to reduce the amount of used tapes)? is it a good idea?
- in your opinion, hardware compression may increase (or decrease) backup performance?

Many thanks,
Mauro

To answer (1):

If you update the drive definitions to just use ULTRIUM4C, compression is forced from a hardware viewpoint. You can also force compression (software side) by setting 'compression=yes' on the nodes.

To answer (2):

Personally, I would set the drive for compressed and non-compressed (ULTRIUM4C and ULTRIUM4), and the nodes to compression=client. There are times compression is not desirable and may slow down performance. However, the impact should not be that big.