StoreEver Tape Storage
cancel
Showing results for 
Search instead for 
Did you mean: 

LTO 2 tape drive capacity for Unix and Windows

unix adm
Regular Advisor

LTO 2 tape drive capacity for Unix and Windows

Hello Experts!

Good Morning!


I am just little bit confused if there is any difference in LTO2 tape capacity when it writes windows data or when it writes Unix data.

On LTO2 tape, my windows server backup is asking for mount request writting up to 400 GB however my unix server backup using the same drive and master server drive writing up to 469 Gb on a single tape and still not asking for mount request.

I understand LTO 2 has capacity of 200/400 GB.

Then what could be reason for this difference?

Thanks in advance.

Rajeev
4 REPLIES
Uwe Zessin
Honored Contributor

Re: LTO 2 tape drive capacity for Unix and Windows

> LTO 2 has capacity of 200/400 GB.

The first value means how much data can be stored on the medium without using compression. The second value _assumes_ a 1:2 compression of the data.

Not all data can be compressed well, so you can see more or less than 400GB written - even when using the same operating system.
.
unix adm
Regular Advisor

Re: LTO 2 tape drive capacity for Unix and Windows

If all data can not be compressed it should be less than 400 GB , how it can be more than 400 GB ?
Uwe Zessin
Honored Contributor

Re: LTO 2 tape drive capacity for Unix and Windows

If all data cannot be compressed at all - you should see 200GB - the 'native' capacity.

If it is more than 400GB, the data had been compressed better than 1:2

469GB = 1:2.345 compression ratio

-----

Let's face it: specifying a 1:2 is just a marketing thing. It depends on the compressibility of _your_ data how much fits on the tape. All the vendor can guarantee is the 'native' value, e.g. 200GB.
.
Víctor Cespón
Honored Contributor

Re: LTO 2 tape drive capacity for Unix and Windows

The tape has a capacity of 200 GB. Forget any other number.

The amount of data that fits in 200 GB using compression depends on how compressible the data is.

You can fit 1 PB of data on that tape. Just create 4 million BMP files of 10000x10000 pixels, that are all black. Once compressed they will take very little space.