From: Dan L. <da...@la...> - 2014-02-10 19:44:30
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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/ |