Tape drive compression issue?

[blu4]

Hi,

 

We have got a Tanberg tape drive with Fujitsu tapes at school. They are LTO5 and are rated at 1.5TB uncompressed and 3TB compressed. We use Symantec Backup exec for backup. The strange thing is, compression is a mere 1.1:1... Could this be a hardware issue or software issue? I posted this in hardware because it is enabled to hardware compression.

[localzuk]

It really depends on what you're backing up. If it is lots of videos, photos and zipped files, your compression ratio is going to be poorer than if it were mostly word documents.

[blu4]

The thing is, the files are mostly word documents... Few pictures and program specific files like Photoshop and After Effects. I'd say that the data is 70% word docx.

[DMcCoy]

Are you using software or hardware encryption? Some older versions of BE do not recognise LTO5 as having hardware encryption either, so it drops back to software. You will get virtually no compression if it is software encrypted first.

[blu4]

Are you using software or hardware encryption? Some older versions of BE do not recognise LTO5 as having hardware encryption either, so it drops back to software. You will get virtually no compression if it is software encrypted first.

 

You mean compression instead of encryption right? We use Backup exec 2012 so it does support hardware compression. We have it set to "Hardware, otherwise software" for compression setting. Could it be that it skips hardware and does software even though it CAN support hardware?

[Mcshammer_dj]

What is the OS of the server and is the data on a drive that is already compressed Edited October 6, 2014 by Mcshammer_dj

[blu4]

What is the OS of the server and is the data on a drive that is already compressed

 

Windows Server 2008 R2

[Mcshammer_dj]

and is the data on drives that have either compression or anything like that on them.

[blu4]

What is the OS of the server and is the data on a drive that is already compressed

The drives are empty, no data there.

[Mcshammer_dj]

I mean the data you are backing up. Are there any restrictions on these drives. It may be that the system is simply not able to compress the data.

 

Of interest what amount of data are you able to backup

[blu4]

I mean the data you are backing up. Are there any restrictions on these drives. It may be that the system is simply not able to compress the data.

Of interest what amount of data are you able to backup

 

I have got 2.75TB of data to back up. The tapes are 1.5TB uncopressed and 3TB compressed. I hope to get at least 1.6/1.7:1 compression. No restrictions on the drives.

[Mcshammer_dj]

So when you run a backup how much are you able to get onto each tape

[blu4]

About 1.8TB-1.9TB- could it be that Backup exec has some hidden compression options?

[Mcshammer_dj]

That is not bad, remembering that the overhead will mean that a reported dataspace will not be the full 1.5TB (uncompressed) and that the data may not all be compressable etc you are gettings quite a good level.

 

When you look at the compresion ratios the best option is the reported 2:1 , and the worst will be 1:1. In my experience the amount I have tended to see with tape compression tends to be nearer 1.2:1 if you are lucky

[Mcshammer_dj]

Found this on the Symantec site:

 

As an update Symantec have found two conditions relating to compression in BE 2012

 

1) is Do not use the compression setting "Hardware if Available otherwise Software" which is already mentioned in this thread. We are working on a fix for this but for now use "Hardware if available otherwise none"

 

2) is the Admin console displays the compression as 1:1 - this appears to be a cosmetic/display issue a full backup of a known set of datat to tape as an overwrite and then compare byte count of data set with amount used on tape youw ill find compression has taken place. Agsin we are working on a solution to this.

 

Of course there may still be an unidentified cause out there so please log cases if the above information does not solve your issue

[DMcCoy]

You mean compression instead of encryption right? We use Backup exec 2012 so it does support hardware compression. We have it set to "Hardware, otherwise software" for compression setting. Could it be that it skips hardware and does software even though it CAN support hardware?

 

No, I mean encryption, you can set an encryption key for backup jobs. If you use hardware encryption and hardware compression, then backup exec hands the data and the key to the drive, which compresses it then encrypts it.

If you use software encryption and hardware compression then backup exec encrypts the data and hands it to the drive, encrypted data is virtually incompressible, which is why you want hardware for both if you use encryption.

 

2012 should be fine with hardware for both, 2010 supported compression for LTO5 but not encryption iirc which is why I asked.

[DMcCoy]

Oh, and remember docx is already compressed, it's really a zip.

[blu4]

Thanks for all the replies. I will try all of the above suggestions and report back.

[LeMarchand]

FWIW, I just checked the compression on the tapes at this site and they're getting 1.2:1. I've never seen a tape reach anything like the "full" compressed ratio of 2:1.

[blu4]

Well, I guess you are right about that... Shame we cant get at least 2.5TB from one tape :<