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If
you put 4GB memories (2 X 2GB) xen-3.0.2-2 crashed to and if when we put
2Gb (2 X 1 GB) it works fine. So 16Gb is not the problem.!
We
have tried new memory and we have the same crash.
So if I put 2gb memories it's crashing with
xen-3.0.2-2, but it's work fine with redhat 4.1 kernel, xen-3.0.1 So or only
explanation is that xen-3.0.2-2 have a problem with 2 GB memories
I disagree. First and
foremost because Xen itself has not knowledge of what combination of memories
(type of module or otherwise) you
have.
However, it may EXPOSE
some problems that previously didn't occur, due to some other scenario... For
example, the new version of Xen may have a different memory access pattern
that causes a failure to happen because there's some particular
sequence of memory accesses, which doesn't happen in the same way with Xen 3.0.1
or plain RedHat. I've worked with hardware long enough to know that "strange
things happen" when you mix different hardware and software.
One thing to consider is
to upgrade the BIOS on the machine, just in case there's some sort of bug in the
memory configuration code in the BIOS. Here's how it works: The BIOS recognizes
your memory chips (from the SPD), and then sets up the timing parameters, memory
sizing parameters, number of banks and some other miscellaneous parameters. Once
this setup has been done, nothing touches the memory configuration registers
ever again. Xen has absolutely NO CODE to touch these registers, so how can Xen
itself fail with one memory configuration when another similar one works - well,
because the ORIGINAL setup didn't work right. But it's not Xen's fault.
Please feel free to
pursue Xen as the culprit if you wish, but I can 100% guarantee you that it's
going to end with you fiinding that it's the memory and/or BIOS and/or
motherboard that is ACTUALLY causing the problem. I know this, because not only
have I worked with Xen for the last year and a bit, but I've also written memory
sizing/configuration algorithms for startup of the processor (like what you find
in the BIOS).
Try running Memtest86 on
the 2GB memory sticks and see if that shows anything. That is NOT GUARANTEED to
show a problem, but it's a good starting point for figuring out that the memory
is good or bad.
Just to confirm that
software can influence the memory errors, I ran memtest86 as a HVM instance
under Xen - so running the virtual machine doing memory testing. I got memory
errors. I then ran memtest86 on the machine itself, no errors. Changing to a
different memory module (from a different manufacturer), fixed the problem. It's
still not Xen's fault that the memory fails, it just changes the access pattern
by locating things in a different way, and in the case of HVM models adding
memory mapping to the not-usually-memory-mapped test-case, so there will be a
different memory access pattern when running the HVM guest compared to running
the bare-metal version.
--
Mats
Ragard Kevin
-----Oorspronkelijk
bericht-----
Van: Petersson, Mats
[mailto:Mats.Petersson@xxxxxxx]
Verzonden: Thursday, August 24, 2006
12:00 PM
Aan: Kevin van Kuik;
xen-users@xxxxxxxxxxxxxxxxxxx
Onderwerp: RE: [Xen-users] Memory
problem's 2GB mod
Xen has absolutely no idea what type of memory modules
you're using, so obviously this is not DIRECTLY causing the problem.
Have you tried runnign a memory test on the 16GB
memories? It may just be that a slightly different setup of memory (caused
by arbitrary changes in Xen 3.0.1->3.0.2) causes you to hit some bad spot
in the memory.
To utterly prove that it's not a "module" issue, you
could also try running 4 * 2GB instead of 8 * 1GB, which should have the
same effect.
The only place where the actual configuration of the
memory is known is within the BIOS that sets up the memory configuration
early on in the boot process (before you see any text on your monitor).
Beyond that, no software will touch anything that is related to what type or
model of memory you're using [except for some utilities that are able to
READ the memory configuration registers to tell you what type of memories
you're using, etc, etc].
--
Mats
I have a HP ml370 with xen-3.0.1 and redhat 4.1 with 16
GB memory (8 x 2GB). I want to upgrade to xen-3.0.2-2 because the server
crashed on the scsi driver.
If I boot the server with xen-3.0.2-2 it crashed on the
boot. But if I put 8 x 1GB memory the server boot fine.
So xen-3.0.2-2 can't work with 2GB memory modules. Is
there a compile option to solve this problem?
The memory is OK because it's work fine with redhat 4.1
(without xen) and xen-3.0.1
regards
Kevin
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