 | | | RHEL + SAN feedback [long] | RHEL + SAN feedback [long] 2005-06-27 - By Al Tobey
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On Mon, 2005-06-27 at 12:38 -0700, Tobias Speckbacher wrote:
Hi guys,
>
> We are currently evaluating the implementation of a SAN to work in
> conjunction with an Oracle 10gR2 RAC. The host OS will be RHES 3 or 4.
> The hba's of choice are going to be QLogic cards.
>
> The SAN products we have narrowed our choice down to are the HP EVA-6000
> and the EMC Cx500.
>
> This will be our first SAN, thus I do not have any working experience
> with either system.
>
> If you have worked with either of these (EVA-6000 is pretty new,
> EVA-3000 or 5000 exp should do) I would appreciate your feedback.
>
> My main criteria are in order of importance:
>
> 1. Management
I have a 9i RAC cluster on RHEL 3 on EVA 5000 storage. We use Qlogic
(HP re-branded FC2312's - two GBICs on one PCI card) with HP/Brocade
switches. I typically run HP's driver, which is just a release from
Qlogic that they've blessed. Redhat typically picks those drivers up
fairly soon after HP and I've also had no trouble with RedHat's
shipped driver. Maintaining a driver binary outside Redhat's is a
bit tedious and not explicitely supported by them, so I recommend
using the on included with your distro - it'll work fine.
I was recently trained on the EVA's management interface. It took
about 5 minutes, most of which was explaining how we laid out the disk
rather than how to use the tool. Allocating disk takes less than 5
minutes per/lun if you take your time. Setting up multipathing on
the Qlogic card is very easy using HP's fibreutils package (search for
FCA2214 on HP's driver page). Dag Wieers has a tool that sets this
stuff up, too: http://dag.wieers.com/home-made/qla-autoconf/.
> 2. Scalability
Currently, the EVA 3000 and 5000 do not support active-active at the
array level, although I believe the EVA 6000 does. Failover support
for the Qlogic+EVA has worked flawlessly without much effort to set it
up. So, if you're looking to do more than 2GB/s to your servers,
you'll want to find out more about active-active support on the EVA
6000. I would not recommend Veritas on Red Hat as you'll be better
off in the long run using Qlogic with failover and waiting for RH to
support active-active with device-mapper+CLVM. Then again, I have no
experience with Veritas on Linux, so take that with a grain of salt.
You should contact Redhat or Oracle (or both!) to determine if you can
set up something on RHEL4 that is supported. RHEL4 has a lot of
features that make management much easier (like on-line resizeable
filesystems). The main hold-back is that OCFS is not supported on
the 2.6 kernel, OCFS2 is not released yet, and AFAIK GFS is not
certified for RAC yet. So, from a support point of view, you'll
probably want to go RHEL3+OCFS, if only to make sure you have a
certified clustering file system. I know there are other CFS's out
there, but have no experience with them and I'm intentionally ignoring
raw disk.
We put our Oracle binaries on a local ext3 filesystem. Getting Data
Protector (HP's backup product - sense a theme yet?) to back OCFS
volumes up is tricky, but not hard once you know how (hint: vi
/usr/omni/bin/.util).
> 3. Support
My personal opinion is that the HP array is the way to go in the long
run because you can easily stay away from binary kernel modules.
Both Red Hat and Oracle have a much better chance of supporting you if
they don't have to wonder about what binary modules are doing to your
kernel. AFAIK, the Qlogic drivers are fully supported by both
Redhat _and_ HP. Once CLVM is available, you'll have a
fully-supported cluster LVM, too.
> 4. Performance
This is largely dependent on how you configure your array, but I have
had no complaints about performance on our Linux/EVA disk. Then
again, our RAC instance on Linux is low-volume. We do have a number
of dev/test HP-UX/Oracle instances and our Exchange server on the same
array and they also are rarely the subject of performance complaints.
In closing:
If I sound like a guised HP sales person, I'm not. I just work at a
shop that has done well by having an all-HP environment, from a
support perspective. Over all, I've been very happy with the EVA5000
+ Qlogic + HP combination. The EMC array is probably comparable on
almost all points except for the driver support. If you need a full
4GB/s load balanced pipe to the array, you'll probably get there
faster with EMC PowerPath. I believe this will be available at some
point for the EVA 6000 if it is not already. Failover support on
EVA+Qlogic is free and quite reliable.
I haven't seen Dag Wieers or Ed Wilts pipe in on this thread yet, but
I know they both have experience with these arrays and HBAs, so you
might find some wisdom from them (highly recommended!) if you search
the archives - try "qlogic" and "HP EVA".
Lastly, dual pathing is probably the single most important "best
practice" when implementing a SAN. In my experience, most of the
problems people have with their SAN are due to having some single
point of failure in the path between the host and disk, be it a
switch, an HBA, or an array controller. If you go through and count
all the pieces of your SAN and come up with an odd number, something
isn't quite right.
2 HBAs/server, 2 switches, 2 array controllers
Many shops (like mine) even go with 2 arrays (one production, one D.R.).
-Al Tobey
> If you think that order is odd, i can elaborate on that in a followup
> email.
>
> Thanks in advance,
>
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