I've been using/managing tape library for many years, still remember I spent 3 days searching for a nonpropretary virtual tape library for my tape application development. I couldn't find one at that time, so I made pretty one just for my development. Now, I don't have to fight with test library anymore, but this one still caught my eyes, couldn't help not to try it. Great!
mhvtl is a linux virtual tape library program, its kernel module is based on scsi_debug kernel module, mhvtl.ko is a pseudo HBA (LLD).
Its target devices are vtltape and vtllibrary.
Utilite commands mktape, vtlcmd
And startup scripts build_library_config(1), make_vtl_devices(1)
As of version 1.4-9, mhvtl can emulate most popular tape libraries.
List of Emulations
Working emulations
IBM LTO (1/2/3/4 & 5) (LTO 5 emulation does not support LTFS)
HP LTO (1/2/3/4 & 5) (LTO 5 emulation does not support LTFS)
IBM 03592-J1A, 03592-E05 & 03592-E06
STK 9840 (A/B/C/D), 9940 (A/B)
STK T10000 (A/B/C)
Sony AIT (1/2/3 &4)
What about model X....
Quantum (DLT/Super-DLT) is NOT supported as their SCSI Programmer's Guide does not document the expected returned data.
DDS (4mm DAT) - I've not found any SCSI programmers' Guides for these drives.
Library emulation is coming in the future.
STK L180/L700 emulation works for NetBackup & NetWorker.
TSM - IBM library type needed to use LTO drives.
Note: Currently, only the tape module has 'personality modules'
Installation
Two packages are needed and they are in ELREPO on RHEL6/SL6 and CentOS. Though they are one version behind git, they stil look good.
#rpm --list *mhvtl*
kmod-mhvtl.x86_64 1.3-1.el6.elrepo @elrepo
mhvtl-utils.x86_64 1.3-1.el6.elrepo @elrepo
lzo will be installed as indenpents
Config and run
It's simple, just run the command below.
/etc/init.d/mhvtl start
By default, the default tape file location is /opt/mhvtl, so if you want to use different filesystem/directory for virtual tapes, make a symbol link(no option to change so far, hope in future release, the location can be change in configuration)
ln -s /opt/mhvtl <your virtual location>
As for library, there are two libraries configured, they are in /etc/mhvtl. I changed one to IBM TS3500, I put /etc/mhvtl/device.conf origional and new output here, you can see not much need to be changed.
< Vendor identification: IBM
< Product identification: 03584L32
origional one
> Vendor identification: STK
> Product identification: L700
Configuration change needs a restart to take effect, so after restart, it looks like this.
Show scsi devices
#lsscsi -g
[1:0:0:0] cd/dvd NECVMWar VMware IDE CDR10 1.00 /dev/sr0 /dev/sg0
[2:0:0:0] disk VMware, VMware Virtual S 1.0 /dev/sda /dev/sg1
[3:0:0:0] mediumx IBM 03584L32 0103 /dev/sch0 /dev/sg10
[3:0:1:0] tape IBM ULT3580-TD5 0103 /dev/st0 /dev/sg2
[3:0:2:0] tape IBM ULT3580-TD5 0103 /dev/st1 /dev/sg3
[3:0:3:0] tape IBM ULT3580-TD4 0103 /dev/st2 /dev/sg4
[3:0:4:0] tape IBM ULT3580-TD4 0103 /dev/st3 /dev/sg5
[3:0:8:0] mediumx STK L80 0103 /dev/sch1 /dev/sg11
[3:0:9:0] tape STK T10000B 0103 /dev/st4 /dev/sg6
[3:0:10:0] tape STK T10000B 0103 /dev/st5 /dev/sg7
[3:0:11:0] tape STK T10000B 0103 /dev/st6 /dev/sg8
[3:0:12:0] tape STK T10000B 0103 /dev/st7 /dev/sg9
Check scsi VPD
#scsi_id --page 0x80 --whitelist --device=/dev/sg10
SIBM 03584L32 XYZZY_A
#scsi_id --page 0x80 --whitelist --device=/dev/sg11
SSTK L80 XYZZY_B
#scsi_id --page 0x80 --whitelist --device=/dev/st0
SIBM ULT3580-TD5 XYZZY_A1
#scsi_id --page 0x83 --whitelist --device=/dev/st0
350223344ab000100
Check device tree
It's from a pseudo adapter, so you can't get it from lspci
#udevadm info -a --path=/class/scsi_tape/st0 | grep "looking at device"
looking at device '/devices/pseudo_0/adapter0/host3/target3:0:1/3:0:1:0/scsi_tape/st0':
#udevadm info -a --path=/class/scsi_changer/sch0 | grep "looking at device"
looking at device '/devices/pseudo_0/adapter0/host3/target3:0:0/3:0:0:0/scsi_changer/sch0':
scsi2_logic
I also tried to use stinit to initialized scsi2_logic for LTO tape drives, they are all succeed, support global blocking.
#mt -f /dev/fctd51 seek 0
#tar tvf /dev/fctd51
-rw-r--r-- vtl/vtl 3136 2013-08-30 06:24 ./device.conf
-rw-r--r-- vtl/vtl 3132 2013-08-30 06:23 ./device.conf.orig
-rw-r--r-- vtl/vtl 1373 2013-08-30 01:48 ./library_contents.10
-rw-r--r-- vtl/vtl 1453 2013-08-30 01:48 ./library_contents.30
-rw-r--r-- vtl/vtl 206 2013-08-30 01:48 ./mhvtl.conf
#mt -f /dev/fctd51 tell
At block 2.
vtilibrary
Media changer works beautifully too
Check library status
#mtx -f /dev/sg10 status
Storage Changer /dev/sg10:4 Drives, 43 Slots ( 4 Import/Export )
Data Transfer Element 0:Full (Storage Element 30 Loaded):VolumeTag = F01030L5
Data Transfer Element 1:Empty
Data Transfer Element 2:Empty
Data Transfer Element 3:Empty
Storage Element 1:Full :VolumeTag=E01001L4
Storage Element 2:Full :VolumeTag=E01002L4
Storage Element 3:Full :VolumeTag=E01003L4
Storage Element 4:Full :VolumeTag=E01004L4
Storage Element 5:Full :VolumeTag=E01005L4
Storage Element 6:Full :VolumeTag=E01006L4
Storage Element 7:Full :VolumeTag=E01007L4
Storage Element 8:Full :VolumeTag=E01008L4
...
Unload tape catridge
#mtx -f /dev/sg10 unload 30 0
Unloading drive 0 into Storage Element 30...done
It doesn't emulate time cost which mechnical movement would have, so when you use it for development, count this factor in, other than that, nothing to complain.
Check out more details in https://sites.google.com/site/linuxvtl2
Note: By default, this virtual tape library generates numerous lines of logs to syslog, even its kernel debug is turned off, I did some effort to discard/separate message mhvtl created, see How to filter mhvtl generated syslog message
