[stgt] complete guide for tgt VTL setup

[ronnie sahlberg]

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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