Chris's Wiki :: blog/tech/ISCSIOffloadPuzzle Commentshttps://utcc.utoronto.ca/~cks/space/blog/tech/ISCSIOffloadPuzzle?atomcommentsDWiki2008-07-31T13:06:13ZRecent comments in Chris's Wiki :: blog/tech/ISCSIOffloadPuzzle.By Chris Siebenmann on /blog/tech/ISCSIOffloadPuzzletag:CSpace:blog/tech/ISCSIOffloadPuzzle:238394b4bb0e8e4320d85a43c10e2ecf8e394c31Chris Siebenmann<div class="wikitext"><p>The HP has whatever hardware a default configured HP DL320s has and
all of the IO was streaming writes. I certainly expect a default
configuration hardware RAID to perform adequately (and at least
non-catastrophically) on the easiest IO load to handle.</p>
<p>(I really doubt that the Linux kernel is asking the hardware to
synchronize the cache to disk after every stripe write or something.
If the HP has decided to do it anyways, that's a hardware issue.)</p>
</div>2008-07-31T13:06:13ZFrom 81.18.0.241 on /blog/tech/ISCSIOffloadPuzzletag:CSpace:blog/tech/ISCSIOffloadPuzzle:150ae1732778c4ab227175bb0d02d95870d99d7aFrom 81.18.0.241<div class="wikitext"><p>On the issue of the HP harware-raid performing poorly: do you have a battery backed accelerator board installed ? If you don't the raid controller will have very poor performance because write caching is turned <code>off</code> on the drives to insure data integrity.</p>
</div>2008-07-31T08:44:08ZBy Chris Siebenmann on /blog/tech/ISCSIOffloadPuzzletag:CSpace:blog/tech/ISCSIOffloadPuzzle:88ad6062dcc54715146334791a272e8bfecd949eChris Siebenmann<div class="wikitext"><p>I don't have any experience with iSCSI accelerator cards. The HP DL320s
I'm (partly) testing with is doing iSCSI through a regular Broadcom NIC,
which it can drive at gigabit data rates (assuming that your disks can
go that fast).</p>
<p>Given that there are so many iSCSI parameters to set and fiddle with,
the thought of having all of that on the card scares me.</p>
<p>(I suppose dedicated iSCSI HBAs do have one potential advantage: they
limit how much damage a compromised initiator machine can do on the
iSCSI network, since they don't give it a real network connection there.)</p>
</div>2008-03-26T20:59:29ZFrom 164.116.253.111 on /blog/tech/ISCSIOffloadPuzzletag:CSpace:blog/tech/ISCSIOffloadPuzzle:26ff4fd698d1a5d06b82150940a79a30448b83c7From 164.116.253.111<div class="wikitext"><p>You were using the HP iSCSI Accelerator? </p>
<p>I was searching for info on it and came across this page, but I see that supported OS' for it are listed in the following A from the FAQ</p>
<p>"It supports Windows 2000, Windows 2003 32-bit and ES."</p>
</div>2008-03-26T15:48:13ZFrom 131.251.5.84 on /blog/tech/ISCSIOffloadPuzzletag:CSpace:blog/tech/ISCSIOffloadPuzzle:f31616d0a121657db06454f6bb6d4d2ef87dea2cFrom 131.251.5.84<div class="wikitext"><p>Nope, bootable iscsi luns make a lot of sense. The card is usually configurable with
a firmware utility, sometimes even open source ones.</p>
<p>Also there are OSes with non-existent (or really shitty) iSCSI support that cope a lot
better when they think they're talking to a standard SCSI HBA.</p>
</div>2008-02-21T10:45:48ZBy Chris Siebenmann on /blog/tech/ISCSIOffloadPuzzletag:CSpace:blog/tech/ISCSIOffloadPuzzle:89f9859ff30b12dc297bf2da52dd1c6c8a27d20fChris Siebenmann<div class="wikitext"><p>Given that iSCSI is a complex protocol with a lot of configuration
on top of TCP (itself not a simple protocol), I'm not sure how you
can have a reasonable 'iSCSI HBA' card that can boot a system from
iSCSI storage. Such a card would either be PC-only and have a huge
boot-time ROM or be something awfully close to a separate computer
running its own code.</p>
<p>(And do people actually boot machines from iSCSI storage instead of
from local disks?)</p>
</div>2008-02-19T00:00:48ZFrom 198.137.214.33 on /blog/tech/ISCSIOffloadPuzzletag:CSpace:blog/tech/ISCSIOffloadPuzzle:c6a11b4e0617d3eb99b9268680ba5c020d0fb15cFrom 198.137.214.33<div class="wikitext"><p>Bootability.
-Alex * <a href="http://alexharden.org/">http://alexharden.org/</a></p>
</div>2008-02-15T21:52:49Z