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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@2037 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Vladislav Bolkhovitin
2010-09-03 14:37:19 +00:00
parent 0c825d11b1
commit 4d2e6d4eff
4 changed files with 163 additions and 67 deletions
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www/contributing.html
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@@ -36,9 +36,7 @@
<ul>
<li><span>By sending donations. They will be spent on further work making SCST better as well as on providing
better support and troubleshooting for you. Donations can be on one time or per period of time basis,
from companies or individuals. They can be sent by direct bank transfer or using
Western Union, Moneygram or similar payment systems. Unfortunately, more convenient options,
like PayPal, are not available in Russia.</span></li>
from companies or individuals.</span></li>
<li><span>By sending patches, which fix bugs or implement new functionality.
See below a list of possible SCST improvements with some possible
implementation ideas.</span></li>
@@ -49,10 +47,6 @@
<li><span>By reporting bugs or other problems.</span></li>
</ul>
<p>Contributing in SCST, you investing not only in making Linux the best storage OS, but, if your company
has a product or service, based on SCST, you also investing in the secured future of your product
or service and, hence, in the the secured future of your company.</p>
<h1>Possible SCST extensions and improvements</h1>
<A NAME="ZC_READ"></A><h3>Zero-copy FILEIO for READ-direction commands</h3>
@@ -282,18 +276,26 @@
<A NAME="SG_LIMIT"></A><h3>Solve SG IO count limitation issue in pass-through mode</h3>
<p>In the pass-through mode (i.e. using the pass-through device handlers
scst_disk, scst_tape, etc) SCSI commands, coming from remote initiators,
<p>In the pass-through mode (i.e. using the pass-through device handlers like
scst_tape, etc) SCSI commands, coming from remote initiators,
are passed to local SCSI hardware on target as is, without any
modifications. As any other hardware, the local SCSI hardware can not
handle commands with amount of data and/or segments count in
scatter-gather array bigger some values. If you have this issue you will see
symptoms like small transfers work well, but large ones stall and
scatter-gather array bigger some values. For some commands SCST can
split them on subcommands and, hence, workaround this problem, but it isn't
always possible. For instance, for tapes splitting write commands may mean
corrupting the tape data.</p>
<p>If you have this issue you will see
symptoms like small transfers work well, but large transfers stall and
messages like: "Unable to complete command due to SG IO count
limitation" are printed in the kernel logs.</p>
<p>In <a href="sgv_big_order_alloc.diff">sgv_big_order_alloc.diff</a> you
can find a possible way to solve this issue.</p>
<p>
<p>The only complete way to fix this problem is to allocate data buffers with number
of entries inside the SG IO count limitation. In <a href="sgv_big_order_alloc.diff">sgv_big_order_alloc.diff</a>
you can find a possible way to solve this issue.</p>
<p>There are also 2 more patches you can look at:</p>