Cadet 1st Class Cadet 1st Class
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LTO-4 tape marked full with 350 GB data

Hello

I have noticed that my LTO-4 tapes are marked full with less data then 800GB.

Ussually it is 600-650GB, but there are some also marked full with 350 GB.

I use very old HP EML with LTO-4 drives. No errors on hardware.

HP DP 9.09 on Cell Manager and media server

It can happen in environment with slow LAN clients and is called as "shoe-shining".

But I have D2D2T - LAN data are wirtten to FileLibrary Writers on media server disk from array directly attached to that server, and written to tape as object copy.

My tests show that transfer to tape drive is around 60-70MB/s which is not very bad.

I was trying with changing block size, segment size, da buffers both on FileLibrary Writers and tape drives - no success.

Any ideas?

 

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Commander
Commander

Hi Cehapure, 

Is this ocurring for all the lto 4 tapes?

when you format these tapes, are you add the format value manually? or are you using it by default? In any case, its recommended to add the value manually to avoid this issues. 

Also, this is just a view perspective, data protector will full the tapes until it arrives to the final tape mark. 

Thanks

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Cadet 1st Class Cadet 1st Class
Cadet 1st Class

yes that is for all tapes, however some tapes has 700, 600 or even 350 GB data and are marked full - not used for next backup jobs.

I was already trying format with values default / 800000MB - no changes.

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Cadet 2nd Class Cadet 2nd Class
Cadet 2nd Class

Hi,


@CEHAPURE wrote:

yes that is for all tapes, however some tapes has 700, 600 or even 350 GB data and are marked full - not used for next backup jobs.


You're sure these are LTO-4 cartridges? The numbers sound exactly like LTO-3 (even there 350GB is a bit on the low side, it needs an extraordinarily wound-out drive, cartridge or shoe-shining triggering source to end up that low but I've seen it). LTO-3 is 400GB native and may write more when data compresses well (as well as less when it has a lot of rewrites).

That being asked, is the pool in question configured correctly for appending?

HTH,
Andre.

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Cadet 1st Class Cadet 1st Class
Cadet 1st Class

It is marked as LTO-4 cartridges. Any idea how to verify?

On very very rare cases there is 1,2-1,3 TB data on tape.

Pools are appendable.

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