On 03/20/2015 01:06 PM, Dr. Greg Wettstein wrote:
We have had the opportunity to architect, build, maintain and debug
complex converged data and storage networks. The switches on these
networks are a million dollars apiece and there are multiple switches
in multiple data-centers.
The storage, running at about one-half petabyte levels, is all SCST
based and we use Qlogic HBA's and CNA's on both the initiators and
targets. Given the somewhat colorful history with respect to Qlogic
target driver support we had to roll up our sleeves and write an
interface driver which allows SCST to run on top of the Qlogic target
driver in stock Linux kernels.
I just put an integrated patchset which includes SCST 3.0.0, our
target interface driver and a few patches to the in-kernel target
driver we carry to make all of this work correctly and address various
regressions in the stock target driver. You can grab the patchset
from the following URL:
ftp://ftp.enjellic.com/pub/scst/sqa-1.2_scst-3.0.0_3.10.67.patch.gz
All of the storage targets are direct FCOE attachments using Qlogic
8362 CNA's. The above patchset is what we are currently using in
production and it has been validated over hundreds and hundreds of
terrabytes of I/O, which includes exposure to some rather rigorous
fabric and TMF event processing situations. We have also tracked down
some rather elusive switch based FCOE transport issues with this
codebase.
Obviously your mileage may vary.
If you drop the above patch onto a 3.10 kernel source tree and build a
kernel with the appropriate configuration options it should work with
whatever cards are supported by the stock Linux kernel. One of the
patches which is included sets the card to QLA2XXX_INI_MODE_EXCLUSIVE
which causes the card to come up 'target capable' by default which
mirrors the behavior of the SCST supplied Qlogic target driver.
In your note you indicate your card is a 'QLogic QLE8362 - 7101674,
Sun Storage 16Gb FC PCIe Universal HBA' which I assume is probably an
OEM rebranded card. The 8362 is actually a Converged Network Adapter
(CNA) rather then an HBA. The 2672 is the 'fibre-channel' HBA version
of the card. The stock Qlogic cards are dual-personality cards which
allows their operational mode, ie 16 GBPS FC or 10 GBPS ethernet, to
be selected through the BIOS setup utilities.
Given your e-mail address, I'm sure you've jumped through all these
hoops but one obviously wants to have the card setup with the right
personality and correct optics for your physical transport layer.
You also probably want to make sure you have both your HBA/CNA and
motherboard up to the most recent versions of their respective
firmware. There are issues particularly with Intel S2600 motherboards
and these cards which requires updated firmware on both sides.
If the card is detected and found to be target capable by the stock
Linux kernel Qlogic driver you will find the available target PWWN's
in the following directory:
/sys/kernel/scst_tgt/targets/sqatgt
If there are none present there is the possibility that the card has
been modified in firmware to prohibit target mode or has a modified
PCI id which is causing problems for the driver probe logic. If that
is the case the card isn't going to be a candidate for use in target
mode. We tend to recommend that people buy straight Qlogic branded
cards to avoid these sorts of issues.
Just as an FYI/CYA there are session management issues/bugs in the
Qlogic target driver, regardless of breed; SCST, Qlogic SCST or
kernel. These can show up during asynchronous fabric processing
events, particularly if you are aggressive in placing the card and
fabric under duress.
We are in the process of upgrading our patchset to 3.0.1 which will
include a number of additional fixes to the in-kernel Qlogic target
driver. I will shoot a note off to the list when it is available if
you or others find this stuff useful.
I hope the above is helpful.
Hello Greg,
Having to download an SCST target driver that is not in the SCST tree is
inconvenient for SCST users. If we would add your version of the SCST
QLogic target driver in the SCST tree, would you be willing to maintain
that target driver ? We can provide help to make sure that that driver
builds against multiple kernel versions. If you want I can send you a
copy of the output of the SCST nightly build process. That nightly build
process checks whether SCST and its target drivers build correctly
against a wide range of kernel versions.
Bart.
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