[Ukfreebsd] FreeBSD and LTO 3 tape drives

andy thomas andy at time-domain.co.uk
Thu Aug 15 23:36:11 BST 2013


For a long time I've been using LTO 3 Ultrium tape libraries connected to 
a Slackware Linux server for backups using Bacula along with the mt & mtx 
tape utilities. This is all working fine but since I'm using FreeBSD for 
most other things now, I thought I'd migrate to FBSD 9.1 to take advantage 
of the ZFS support when moving to a larger server.

But this hasn't worked out too well as mt doesn't seem to fully recognise 
LTO 3 drives - it gets the tape density code right (0x44) but that's all:

    root at replicant2:/root # mt -f /dev/sa1 status
    Mode      Density              Blocksize      bpi      Compression
    Current:  0x44                 variable       0        0x1
    ---------available modes---------
    0:        0x44                 variable       0        0x1
    1:        0x44                 variable       0        0x1
    2:        0x44                 variable       0        0x1
    3:        0x44                 variable       0        0x1
    ---------------------------------
    Current Driver State: at rest.
    ---------------------------------
    File Number: 0  Record Number: 0        Residual Count 0

A SDLT 320 tape drive on the same controller and external SCSI bus returns 
much more information:

    root at replicant2:/root # mt -f /dev/sa0 status
    Mode      Density              Blocksize      bpi      Compression
    Current:  0x49:SDLTapeI(160)    variable       193000   IDRC
    ---------available modes---------
    0:        0x49:SDLTapeI(160)    variable       193000   IDRC
    1:        0x49:SDLTapeI(160)    variable       193000   IDRC
    2:        0x49:SDLTapeI(160)    variable       193000   IDRC
    3:        0x49:SDLTapeI(160)    variable       193000   IDRC
    ---------------------------------
    Current Driver State: at rest.
    ---------------------------------
    File Number: 0  Record Number: 0        Residual Count 0


FBSD seems to recognise the tape drive hardware OK:

    root at replicant2:/root # camcontrol devlist
    <COMPAQ CD-ROM SN-124 N104>        at scbus0 target 0 lun 0 (cd0,pass0)
    .
    <snip ... hard disk info deleted ... >
    .
    <COMPAQ SDLT320 4B4B>              at scbus5 target 3 lun 0 (sa0,pass7)
    <DELL PV-132T 310D>                at scbus5 target 5 lun 0 (pass8,ch0)
    <IBM ULTRIUM-TD3 5BG2>             at scbus5 target 6 lun 0 (sa1,pass9)

Also, attempts to use the tape library changer interface fail with:

    root at replicant2:/root # mtx -f /dev/ch0 status
    cannot open SCSI device '/dev/ch0' - Inappropriate ioctl for device


Is this a known issue with the FreeBSD tape driver? And has anyone managed 
to get LTO 3 drives working under FreeBSD? The mt man page doesn't list 
the 0x44 density code, although it does list 0x49 as used by the SDLT 320 
drive.

Thanks in advance,

Andy


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