[stgt] complete guide for tgt VTL setup

[ronnie sahlberg]

Ok,  several questions about VTL setup recently.
Ill try to write a small README about it.


For now,   you can use doc/README.mmc
It contains an example on how to build a DVD jukebox which should be
almost identical to how to set up tape VTL

The only difference is really using tgtimg to create "blank tapes"
instead of "blank disks"
and to specify the data transfer device as a tape drive isntead of a cdrom


mtx-gui  on github is a great tool to operate the media changer device !


regards
ronnie sahlberg



On Wed, Jul 25, 2012 at 10:07 AM, Thomas Lau
<Thomas.Lau at principleone.com> wrote:
> Hi, I could but can you attach example configuration file for tgt act as vtl
> target as well?
>
> It's lack of document you know
>
>
> -----Original Message-----
> From: ronnie sahlberg [ronniesahlberg at gmail.com]
> Sent: Tuesday, July 24, 2012 02:36 PM China Standard Time
> To: Thomas Lau
> Cc: stgt at vger.kernel.org
> Subject: Re: complete guide for tgt VTL setup
>
> Hi,
>
> We optimized performance in patches in january this year :
> commit 96e83a2e60857cd5356f99c45f0a0a658f600949
> Author: Ronnie Sahlberg <ronniesahlberg at gmail.com>
> Date:   Mon Jan 23 12:42:14 2012 +1100
>
>     ssc: fsync on the final WRITE-FILEMARK
>
>     Not for the individual WRITE6 calls.
>
>     Add a specific Mode_sense function for SSC devices so we can force the
>     BUFFERED-MODE in the mode sense data to inidcate that we are doing
>     buffered writes.
>
>     Signed-off-by: Ronnie Sahlberg <ronniesahlberg at gmail.com>
>     Acked-by: Mark Harvey <markh794 at gmail.com>
>     Signed-off-by: FUJITA Tomonori <fujita.tomonori at lab.ntt.co.jp>
>
>
> Priuor to this we used to fsync() on every individual write()  which
> was massively expensive.
> Instead it now only calls fsync() once when the file is finished.
>
>
> Centos6.0 is quite old so it is completely possible that it still uses
> a version of tgtd prior to 1.0.24 when this fix was added.
> This fix would improve performance by an order of magnitude or more as I
> recall.
>
>
> Can you compile and install tgtd from GIT and compare the performance ?
>
> regards
> ronnie sahlberg
>
>
>
> On Wed, Jul 25, 2012 at 1:50 AM, Thomas Lau <Thomas.Lau at principleone.com>
> wrote:
>> Dear All,
>>
>> does anyone have a workable config and setup guide for centos 6.x?
>>
>> I am using mhvtl and it's working fine, except the performance is poor.
>>
>> my target is to setup LTO5 emulation with a media changer. --
>
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