AIX

Hi,

LTO5 Data cartridge has 1.5 TB (1500GB) native capacity but when we are taking our 1.44 TB (1475 GB) filesystem backup using backupby filename on these data cartridges it does not fully finish on one cartridge instead it requires another volume to backup the remaining files. I am unable to find out why this happens as we have already 25B less size of filesystem then the capacity of cartridge. For the resolution of this we have reduced our back up filesystem down-to 1375 GB in order to complete it on one volume.

Note that filesystem is backupby filename having default block size 51200 bytes (100 blocks).

Moderator's Comments:

That font was somewhat small; changed it to default.

Terabyte vs Tebibyte perhaps?

1.5TB is approximately 1.4TiB...

Its Terabyte

besides the data, there is also metadata being stored. that must be the drop that is overflowing the tape (bucket).

hope this helps.

Michael its OK fine that metadata is acquiring that space on tape but we noted this happens some times not all the times.
We faced problem again from last two days that our total data filesystem size is 1200GB & we are taking the backup of the same on LTO5 which has capacity of 1500GB. For the resolution of this we further moved our data from filesystem & bring the filesystem size down to 1000GB & took the backup which was successful. I am unable to understand what amount of metatdata was written on tape. Before LTO 5 we were taking 750 GB filessytem size backup on LTO4 which has native capacity of 800GB and we didn't face problem on that. But I don't know what happens with the LTO5.

I can only speculate as you haven't described your environment completely.

What exactly do you mean by "backup by filename"? Might it be that you have sparse files on this filesystem which get expanded during the backup? (This would mean the restore would also fail because the FS won't provide enough space to accomodate the expanded file(s).)

I hope this helps.

bakunin

Many people have issues with LT05 capacities. You mention that your tape drive is 1.5TB native. Does that mean that it's circa 3TB with compression?? What model of LT05 is it exactly? Is hardware compression enabled on it?

Also, what is your backup utility? Are you using tar or cpio or some backup suite? With Unix commands you can normally set the tape capacity and, if you do that, the number of bytes backed up is "counted" as the tape is written and the command calls for a new volume when that number of bytes is reached. It has nothing to do with hitting the actual end-of-tape or anything like that. With some backup suites the tape capacity is often set in a configuration file somewhere.

As other respondees have said, please post more information of your configuration.

Meantime, search for "LT05 compression" on the web.

In this example the discussion covers not getting the 1.5TB capacity even with compression switched off (ie, native) and reformatting tapes to resolve.
LTO5 Tape is not using the complete capacity of 1,5TB (uncompressed) + Compression not working | Symantec Connect Community

Hope that helps. Please post your progress or lack of progress.