Ultrium(LTO) generation 2 ...wat a display!!!

[abhijeet_7]

Hello Gurus,
We are using LTO ultrium (generation 2) tapes.
We have installed HP's data protector (cell manager) s/w .
Being generation 2,it should go uncompressed upto 200 GB(green marking) & above it ,it should start compressing data(red marking).

but,as soon as data reaches 100GB ,it starts showing red marking when checked for usage.

Is it correct?

thanks & advance
abhik

[Kurt Beyers.]

Hi Abhik,

The default size for an Ultrium tape when you format it into DP is 100 GB.

However, DP will use the tape untill the end-of-tape is reached and the size during the format doesn't matter. If you set a size of 1 MB or 1 TB, you still will be writing +- 400 GB of compressed data on the tape (asuming you are using hardware compression).

Else you should reformat the tape and specify a size of 409600 MB. DP will reflect now the correct settings.

The default size can be changed in the global optinos (etc/opt/omni/options/global) file.

best regards,

Kurt

best regards,

Kurt

[Marcel Boogert_1]

Hi there,

This doesn't matter. Eventually DP continues writing to the tape. We have the same issue, I don't have any good explanation for this. All I know is that DP continues to write even if it says the tape is full(100GB).

I believe there is coming a DP5.5 version soon, maybe it is fixed there.

MB.

[Leif Halvarsson_2]

Hi,
The "problem" is that there is only one LTO media type in DP, the 100GB (default) size apply to all LTO medias.

As stated out before, this size is for information only, DP alwaus uses the full media caspacity.

It is possible to change the default size in the global option file.

I don't belive there will be any differences in DP 5.5 .

[Seth Parker]

What you're describing isn't a "problem" at all. It's just an annoying side-effect of data compression. DP knows the capacity of a given type of media based on its settings, and these settings are based on uncompressed data. The "problem" comes in when you enable compression. Since DP can never know ahead of time how much space is going to be saved by compression, it can never know how much data it will be able to store.

Keep in mind that DP is only writing 200GB of information on an LTO2 tape as that's all it can hold. But since the source data is being compressed as it's written, the size of the source data may be much larger than 200GB.

Regards,
Seth