Bar Code label and tape capacity ulitlisation

[PL_3]

Does the bar code label has any effect on the capacity of a tape ? Can I use a Ultrium-1 bar code label on a Ultrium-2 tape? I'm running DP 5.x and using MSL6030 tape library.

[Leif Halvarsson_2]

Hi,
Yes, you can. The label is only uset to identify the media and has no impact on capacity. Also, please note that the capacity value used when formatting is only a "estimated" value. Data Protector always writes the media until physical end.

[Duncan Edmonstone · Accepted solution]

The barcode has no effect on the capacity of the tape from DPs perspective - however I don't know how the MSL will behave itself with a tape with a L1 suffix... maybe a detailed read of the following should provide the answers:

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c00030203

HTH

Duncan

[Leif Halvarsson_2]

Hi,
There is no problem with the MSL. I have used both types of labels on both types of media in a MSL library without any problem

[PL_3]

Thanks for the responses.
I asked this same question to some IT Support on HP and he told me that "The manual says, the library comes to know about media Genration type from the label suffix "L1" or "L2" only."

From the "statement" above, can it be said that the LTO2 media will be treated as LTO1 ,if it's using barcode label with L1 suffix ?

By checking on the history log of the L2 tape utilisation (without using compress format), some tapes stopped before reaching 200GB and some tapes went up to 250 to 290GB.

Anyone has any idea, please ?

[Kurt Beyers.]

PL,

The capacity of data written on a tape does not depend on the suffix of the barcode label.

By default you have 200GB of native data on an Ultrium2 tape and 400 GB of compressed data assuming a compression ratio of 2:1

The true compression ratio is however data dependent, the rule of 2:1 is only a rume of fist (generalization after many observations). Eg if you have a 1 GB Oracle data file that contains only a few records of actual data, the compression ratio will be huge. But if the same data file is completely filled with records, the compression ratio will be around 1.

DataProtector will always use a tape untill the physical end of tape is reached.

best regards,
Kurt

[Leif Halvarsson_2]

Hi,
The answere from "IT Support on HP" is perhaps correct from the perspective of the library but misleading when it comes to DP. The library may "know" about Ultrium 1 and Ultrium 2 but, the library does not write any data to the media, it is done by the application (e.g Data Protector). And, there is only ONE Ultrium media class in DP. So Ultrium 1,2 or 3 makes no difference for DP. Data Protector writes the media to the physical end. Thats's all.

How much data that fit on each media depend on the data you write to it, compression ratio is very data dependant. With hardware compression on, you can get everything from the native (uncompressed) capacity to several TB.

[PL_3]

Hi All,

Thanks for your reply.

I still could not find out why the max size of the L2 backup tapes(with L1 label in my tape libary)in my tapes library is only 150GB. There are below 200GB.

Could there be any setting in the DP that set the max utilisation of tape capacity (trying my luck)?

I could not give a satisfactory answer to my customer because we have another site using the same type of equipment(MSL6030 tape library), Ultrium-2 tapes with L2 label do not have this problem. Each of the tapes capacity is at average of 250GB per tape. (no data compression)

Any idea ?

BR//PL

[Andrzej Kowalik]

DP have predefined format value for LTO tapes. If you want format with another value, you must change defsize value (102400).
regards,
Andrzej

[Leif Halvarsson_2]

Hi,

Is it the same type of data you backup on the two sites ? If not, compression ratio for the data may also be different.

You can do a simple test if you compress some files using zip, compress or another compression utility. Those programs uses algotitms similar to the hardware compression in the drive. In that way you can get an idea about compression ratio for your data.

Also check if volume compression is used.