BE can't compress data writing to tape

[happypumper]

There is BE 2012 which according to daily schedule creates backup using the method "disk to disk to tape". A writing process to a tape run immediately after a disk backup finishes and in this case data written to a tape is compressed, rate of compression is about 2:1, so, everything is ok. I need to get additional tape copies every month to keep data in a remote location. As a result, I create additional job which should copy a last available backup from a disk to a tape and, of course, I enable options which makes BE used compression, however, in this case I get a tape without compression. There is another one noticeable thing which can be related to this trouble which is tape partitions. I separated one library cell as partition and use it when I try to make backup for remote keeping so as process of making additional copies can't influence on daily backup. What might be a cause of this trouble?

[Larry_Fine]

I doubt that the library partition has anything to do with it.

These may help you:

http://www.symantec.com/docs/TECH50960

How to verify Hardware Compression Setting in Backup Exec

https://www-secure.symantec.com/connect/articles/understanding-compression-backup-exec

[happypumper]

I've captured SCSI commands according your instructions and, as a result, almost every "Mode Sense" command doesn't consist nesassery bytes.The majority of these command include the following string:

0B 58 08 58 00 00 00 01 00 00

If my understanding this article is right the cause why the compression doesn't work is located in BE. What can be the reason of such behavior of BE? Another fact which might be releated to this problem is encription. I enable software encription, so, could it prevent compression? 

[pkh · Accepted solution]

If you are using software encryption with hardware compression then yes. Encrypted files compress very badly. See my article below https://www-secure.symantec.com/connect/articles/compression-short-explanation

[happypumper]

Thank you for your article! I've just done several tests and, as a result, this tests proof that the cause of this problem is software encryption. When I turn off it I get normally compressed backup. The normally compressed backup I also get when I enable hardware encryption instead of software. As soon as I return software type of compression again the backup isn't compressed. I have another two questions:
1. When I confige duplication of being excisted copy I can't choose software compression for a tape-library because only hardware compression is available. Is it normal for a tape-library? Shall I enable some additional options somewhere in BE in order to activate this opportunity? The software compressed is still aviliable if I confige backup from server to tape directly. 
2. I enabled for job a software encryptions and a software compression in the same time would this combination work appropriately and would it allow me to get backup which would be compressed? I can hardly use hardware encryption because my tape will be kept in remote location and every tape device should be able to read data from such tapes.

[VJware · Accepted solution]

Software compression not appearing for a Duplicate is expected - http://www.symantec.com/business/support/index?page=content&id=HOWTO22915

If you would like your backups to be encrypted, then better to use software compression than hardware compression. As when software compression is used, BE will first compress the files and then encrypt them, whereas if you hardware compression, it will compress data post the encryption and this is not effective as the data becomes randomized.

[pkh]

1. Yes. This is by design. Only hardware compression is available for a duplicate job. 2. If you want both encryption and compression, you should enable both software encryption and software compression in your backup job. You then duplicate without specifying either encryption or compression. The duplicate job would copy the previously encrypted and compressed backup set to tape

[happypumper]

Thank you, I've solved my problem. So, in order to create copy for remote location I should create an additional job where software encryption and compression should be enabled and it cannot be a duplication job which means that copy should be made directly from server source. However, this solution isn't effective because although there have already been full backup copies we can't just duplicate them and had to do additional copy. And it's a serious problem because a size of our full backup is several Tb and it's illogical to copy such large data from source twice. It would be more effective if we could use backup we've already had instead of getting backup from source. Could you tell me if you have any ideas how it can be implemented?

[pkh]

How can your problem be solved when you don't know how to implement the so-called solution? Also other than duplicating a backup set, there is nothing else that you can do with it. Your imaginary job is not possible