Re: [Bacula-users] bacula fails to fill lto-6 tapes

[Dan L. <da...@la...>]

On 2014-02-03 05:45 AM, Stefano Stalio wrote:
> Hi all,
> I have an Overland Tape library with two LTO6 drives.
> 
> I verified that I can write 2.5TB on each tape both via tar and using
> the btape command (fill test on a single tape).
> Here is the end of the command output, telling me that 2.5TB of data
> were written to tape:
> 
>> Wrote block=39015000, file,blk=2518,1499 VolBytes=2,516,935,615,488 
>> rate=99.83 MB/s
>> Wrote block=39020000, file,blk=2518,6499 VolBytes=2,517,258,175,488 
>> rate=99.84 MB/s
>> 31-Jan 18:21 btape JobId 0: End of Volume "TestVolume1" at 2518:10316 
>> on device "drive0" (/dev/nst0). Write of 64512 bytes got -1.
>> 31-Jan 18:21 btape JobId 0: Re-read of last block succeeded.
>> btape: btape.c:2712 Last block at: 2518:10315 this_dev_block_num=10316
>> btape: btape.c:2747 End of tape 2518:0. Volume 
>> Bytes=2,517,504,417,792. Write rate = 99.82 MB/s
>> btape: btape.c:2318 Wrote 1000 blocks on second tape. Done.
> 
> During backups, though, the tapes are never filled up to that limit:
> 
>> 20-Jan 08:49 gsbacula2-sd JobId 7300: End of Volume "FB7005L6" at 
>> 1668:1 on device "drive0" 
>> (/dev/tape/by-path/pci-0000:04:00.0-fc-0x50050763124cb9db:0x0000000000000000-nst). 
>> Write of 64512 bytes got -1.
>> 20-Jan 08:49 gsbacula2-sd JobId 7300: Re-read of last block succeeded.
>> 20-Jan 08:49 gsbacula2-sd JobId 7300: End of medium on Volume 
>> "FB7005L6" Bytes=1,667,893,312,512 Blocks=25,854,000 at 20-Jan-2014 
>> 08:49.
> 
>> 20-Jan 23:09 gsbacula2-sd JobId 7300: End of Volume "FB7006L6" at 
>> 1402:1 on device "drive0" 
>> (/dev/tape/by-path/pci-0000:04:00.0-fc-0x50050763124cb9db:0x0000000000000000-nst). 
>> Write of 64512 bytes got -1.
>> 20-Jan 23:09 gsbacula2-sd JobId 7300: Re-read of last block succeeded.
>> 20-Jan 23:09 gsbacula2-sd JobId 7300: End of medium on Volume 
>> "FB7006L6" Bytes=1,401,910,336,512 Blocks=21,731,000 at 20-Jan-2014 
>> 23:09.
> 
>> 21-Jan 18:05 gsbacula2-sd JobId 7300: End of Volume "FB7007L6" at 
>> 1625:1 on device "drive0" 
>> (/dev/tape/by-path/pci-0000:04:00.0-fc-0x50050763124cb9db:0x0000000000000000-nst). 
>> Write of 64512 bytes got -1.
>> 21-Jan 18:05 gsbacula2-sd JobId 7300: Re-read of last block succeeded.
>> 21-Jan 18:05 gsbacula2-sd JobId 7300: End of medium on Volume 
>> "FB7007L6" Bytes=1,624,896,064,512 Blocks=25,187,500 at 21-Jan-2014 
>> 18:05.
> 
> Does anybody understand what is going on?

Did you use the same data in both cases?

Data compresses differently.  e.g. video/graphic compress very poorly.  
Text dumps of databases [often] compress very well.


-- 
Dan Langille - http://langille.org/