Re: AIX on JS21 Blades
- From: "F. Michael Orr" <michael_orr25@xxxxxxxxx>
- Date: Tue, 16 Jan 2007 10:31:31 -0500
On Thu, 11 Jan 2007 14:49:24 -0500, Larry Anta wrote:
Okay, I'm getting more confused. :) But please bear with me because I'm
new (two days experience) to this whole chassis/blade world (although I have
years of experience with IBM RS/6000s and with AIX in general).
The H Chassis that we're testing (BladeCenter H Type 8852) has a 20-port
Brocade FC switch (sorry, no p/n or model handy). This switch *part of the
chassis*. Six of the switch ports are exposed at the back of the chassis;
the other 14 ports are internal to the chassis and each of the 14 physical
JS21 blades is automatically connected to an internal Brocade port. I
watched the physical installation of two physical hard disks *plus* an FC
"adapter" (QLogic 4Gb Fibre Channel Expansion Card) into each of the 14
blades, so I'm confused that this is deemed to be unlikely. Maybe "adapter"
is the wrong word (If so, sorry about that.) but it's the piece of hardware
on the blade that permits this internal connection to the Brocade switch.
With this (hopefully clearer) description of my environment, it had better
be the case that IBM supports my JS21s since it's their blades, their
chassis, their (rebranded) FC switch and their SAN technology (DS 4300).
The blades have an HBA and two drives. The switch config as you
describe above is correct. The problem lies in support. AIX running on a
JS21 accessing SAN storage via the above is not supported. Linux running
on the JS21 _is_.
In any case, that's not what my original question was about. :)
I was polling for best practices surrounding the use of the two internal
hard disks on each blade and was attempting to decide between hardware
mirroring of those two internal disks (via the blade's onboard RAID
controller) versus software mirroring with the AIX O/S.
Normally, choosing between hardware and software mirroring is a no-brainer;
I'd go with hardware mirroring for performance. My concern was the manner
in which drive failures are communicated to the AIX administrator, because,
after all, what good is hardware mirroring if a drive failure goes
undetected? I've since been advised (by IBM) that drive failures will be
reported via errpt. This eliminates my concern, so I'm implementing
hardware mirroring (which is set up by booting off the regular diagnostics
CD, by the way). With hardware mirroring in place, the AIX admin sees one
hdisk, even though there are two physical disks behind the scenes. I
surmise that there is some regular polling of the RAID controller by AIX to
enable AIX to report (via errpt) that one of the real physical drives has
failed or that failure is imminent.
I now feel the decision is justified, but still of course welcome
discussion. Cheers!
I would test to make sure. Pull a drive and see if you get an errpt
message. I would not assume that it works, because it has been my
experience that AIX is being treated somewhat as a stepchild on the JS
series.
We don't do H/W mirroring. We do the standard AIX config, with hdisk0
and hdisk1 for each PV, and so far have found it to be acceptable. We
don't, however, do heavy disk I/O on our blades; they are app servers
which exist primarily to do network I/O.
Larry Anta
Ryerson University
Toronto, Canada
.
- References:
- AIX on JS21 Blades
- From: Larry Anta
- Re: AIX on JS21 Blades
- From: sjm
- Re: AIX on JS21 Blades
- From: F. Michael Orr
- Re: AIX on JS21 Blades
- From: Larry Anta
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