Tape Capacity

Hi V,

 

No, data is not selectively deleted off a tape. The OPP protects a tape for a certain period, and the Append allows data to be added to a tape.Once a tape is full, it can't be used until it is overwritable again.

See the TN below for more information:

http://www.symantec.com/business/support/index?page=content&id=TECH5459

The tape capacity is also subject to the type of data being backed up. An LTO4 tape, for instance, can hold 800GB uncompressed, and with 2:1 it will hold 1.6TB. You won't get this in the real world.

Thanks!

When you append to a tape and it gets full, BE will require an overwritable tape for the second and subsequent tapes. BE cannot append to a second tape. It will not write to the front of the tape after appending to it.

Hi guys,

Here are the facts:

-We have 10 LTO5 tapes (Week1 and 2) and One Tape Drive.

-Tape total Capacity 1.4GB

-Compression ratio 3.2:1

- For example the tape I should use for tonights job has only 292GB space free or available Capacity. Our Backups are less than 400Gb but 292 won't be enough. Then this tape is showing under Proteccion Period "Overwriteable" (Our proteccion period is setup to 1 week) and "Infinite-Allow Append"

Then can next backup job be done succesfully on this tape? or should we get the media full/ insert overwritable media message?

What should we do in this case??

Thanks for your help

 

V

 

 

 

Hi guys,

Here are the facts:

-We have 10 LTO5 tapes (Week1 and 2) and One Tape Drive.

-Tape total Capacity 1.4GB

-Compression ratio 3.2:1

- For example the tape I should use for tonights job has only 292GB space free or available Capacity. Our Backups are less than 400Gb but 292 won't be enough. Then this tape is showing under Proteccion Period "Overwriteable" (Our proteccion period is setup to 1 week) and "Infinite-Allow Append"

Then can next backup job be done succesfully on this tape? or should we get the media full/ insert overwritable media message?

What should we do in this case??

Thanks for your help

 

V

...it should start appending to the tape before spanning to another. However, once full, the OPP takes effect. The tape will be overwritable once the OPP threshold is reached. Once this happens, the ENTIRE tape is useable...not just sections of it.

Thanks!

with 400GB required space and only 2929 free but as teh tape is overwritable the way to avoid the inert media message is to make the next job actually start as an overwrite and not an append.

In practice I would recommedn you reduce you append period from infinite down to some sensible number that gives you enough appends but then forces an overwrite eventually

The other option is to setup your jobs so that most start as append but every so often 1 starts as an overwrite

Either of the above ideas will need you to look at your media rotation and the approximate timings for when you might expect to fill a tape in order to decide on appropriate timings

 

 

... means that tape has to be full and reach the OPP threshold in order to have the entire tape useable?

What about if we don't want to use two tape for one job, becasue actually there's nobody in to switch tapes at that time. 

Is there another practice??

Thanks

If you don't want to use 2 tapes you need to make sure all your data fits onto 1 tape.

Or change from FULLto INCR/DIFF backups.

Thanks!

Hi Colin,

We already changed the AP to 1 month, then tonights tape is showing "Not Appendable" , But the OPP is "Overwriteable".

This means BE will force to overwrite it?

I understood clearly about the rotation that needs to be checked.

Thanks a lot

V

 

 

...if the tape is marked as Overwritable, then it is available for write operations.

Thanks!