Tape Compression when using Dedupe-Friendly?

[zuldan]

There are many articles saying it's best not to use tape hardware compression when the source data is already compressed but they don't specify which compression levels that's applicable for. Surely there is a tipping point for when the compression level of the source data is so minimal that it would be worth enabled Tape Compression. For example, what about when the source data is only using the compression level Dedupe-friendly?

[Andreas Neufert]

Double Compression will likely lead into bigger backup files on tape. You can do a simple test in your environment by creating 2 jobs with different settings and back them up to tape.

Compared with the Veeam Optimal compression the compression on tape should not be much higher. So the space saving effect is low. On the other side when you store the Veeam data on disk without compression or with dedup friendly compression, you need much more disk space (nearly 2x) and you process nearly 2x more backup data at the backup disks. Potentially your backups and restores need longer. (Uncompression on the fly by the CPU is faster than your disks).

I would not disable the compression on disk when you backup to normal disks first.

[zuldan]

Hi Andreas, thank you for your response.

I guess my current situation is that we're using an Exagrid as a repository so we have to use either "Dedupe-friendly" or no compression. At the moment we're getting great deduplication ratio's so space saving is high. The problem is that since the data isn't compressed that much we're using a huge amount of tapes each week to backup.

I was hoping that it was best practice to enable Tape Hardware Compression when your source data is massively deduplicated with little compression to reduce the amount of tapes being used. What are your thoughts?

[Andreas Neufert]

Sure, whenever the Compression reduce the backup file on the tape I would enable compression. In your scenario I would enable it for sure.

[zuldan]

Thank you Andreas.

[chris.jones]

Hello. I currently use Veeam to send backups to an ExaGrid appliance using the "Dedupe-Friendly" level of compression. If I enable backup to tape jobs, will Veeam use this same compression to send backups to the tape library (Dell TL2000)? Thanks.

[foggy]

Tape jobs will take the backup files as they are stored on the source storage (compressed) and copy to tape. Additionally, you can enable hardware compression on the tape library.

[zuldan]

Just to report back. After enabling hardware tape compression when backing up jobs on our Exagrid repositories we saw a big reduction of data going to tape. I guess the point is, enabling hardware tape compression on deduped data (that resides on an appliance) is very beneficial. I'm guessing you would not see this benefit if Veeam was compressing and deduping to a standard repository.

[chris.jones]

That's good to hear, zuldan. I'll be sure to enable it for my tape jobs. Thanks for the update.

[Andreas Neufert]

Thanks, yes this is correct. whenever you store the Veeam data uncompressed (on dedup applainces) then you should enable the tape hardware compression setting as the data get´s rehydrated from dedup storage (data is uncompressed and undeduplicated then) and tape compression would reduce data in most cases more than 50%. This would lead into faster streaming to tape (less data needs to be written on tape) and tape amount usage reduction.

Whenever you have already compressed data (like with default backup job settings, backing up to standard storage), Tape compression would likely end up in more data, as double compression produce in most of the cases more data then before.