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LTO-5 Block Size

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Ing. Bernd Rieg Absent Member.
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LTO-5 Block Size

What is the recommended block size for LTO-5 tapes (with DP 6.20)?

I do not have such a drive now, but we are upgrading in the near future.

 

kind regards

Bernd

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Established Member.. andre80
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Re: LTO-5 Block Size

Hi Bernd

 

With LTO3 and above you should use at least 256KB blocksize. I'm not sure how much more improvements you get if you go further up to 512 or 1024. But keep in mind, in case of any disaster restore in offline mode only 64KB Blocksize is supported for ms operating systems. DP does switch to offline restore if cell server is not available/reachable. this can have many reasons...

 

regards

andre

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Established Member.. andre80
Established Member..
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Re: LTO-5 Block Size

Hi Bernd

 

With LTO3 and above you should use at least 256KB blocksize. I'm not sure how much more improvements you get if you go further up to 512 or 1024. But keep in mind, in case of any disaster restore in offline mode only 64KB Blocksize is supported for ms operating systems. DP does switch to offline restore if cell server is not available/reachable. this can have many reasons...

 

regards

andre

Absent Member.. Petr Hanzlik Absent Member..
Absent Member..

Re: LTO-5 Block Size

Hi Bernds,

 

my 10 years experience with size block, performance and compatibility show to 256kB size. Ofcourse, the documentation describe that only 64kB block is supported for DR. I have checked few process DR for Windows platform with 256kB and it was working.

 

Petr

Petr
Established Member.. NXsupport
Established Member..

Re: LTO-5 Block Size

And what is the segment size you take for an LTO4 or LTO5 tape

Absent Member.. gabhaas Absent Member..
Absent Member..

Re: LTO-5 Block Size

Does nobody know anything about segment sizes on LTO5?

It would help me too to know what should be a good size. Somebody told me to use 20.000 MB for segment size and 256KB for Block size. Is that a good choose?

 

Absent Member.. Unix Beheer Absent Member..
Absent Member..

Re: LTO-5 Block Size

Segment size is something really different from blocksize.

 

In the manual it is explained why DP uses segment sizes. In general,don't make them to small. However using very large segment sizes might cause DP to force end of segments if there is more than 13 mbyte of metadata in one segment. This will happen if you backup large numbers of small files, for example. Exact details can be found in the manuals and/or google.

 

On any non-linux media-server 2 to 8gbyte should be fine and should not make any difference in performance. Linux hosts currently have problem the stop/start tape drive when writing filemarkers. So on a linux media/cell-manager you will generally need a bigger segment size to minimize shoe-shining. But if you make them too big, your restore times might increase, since DP will need to do more searching on a tape to get the required information.

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