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Author Topic: rootvg disk faliure caused server crash
Phizzy_Phil
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Icon 1 posted October 18, 2005 11:57      Profile for Phizzy_Phil   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Hi to all,
Sorry to ask work related questions but this has been driving me mad all day....
Does anyone have any ideas why a fully mirrored disk which is part of the root volume group on a HPUX server brought a server down when it failed?
I've checked all the usual places and can't find any evidence.

Thanks for any ideas or unusual places too look

Posts: 26 | From: Nottingham, UK | Registered: Oct 2005  |  IP: Logged
supaboy
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Icon 1 posted October 19, 2005 10:18      Profile for supaboy     Send New Private Message       Edit/Delete Post   Reply With Quote 
I can't offer any help other than the very general:

Verify the configuration is exactly what you think it is!

Last week, some agents where I work came in on Saturday to take phone calls. They sat at a row of computers that were normally unoccupied, and I assumed the computers were all in the state I had left them: freshly-imaged and ready to go.

Of course, two of them had their network cables disconnected and two more of them had had their mice stolen. [Mad]

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Groggle
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Icon 1 posted October 19, 2005 18:42      Profile for Groggle     Send New Private Message       Edit/Delete Post   Reply With Quote 
It depends on what's on that group, and whether it's a hardware mirror or a software mirror, not to mention what version of HP-UX you're on. I'm guessing that swap was on the same volume group for most of what follows.

If the mirroring was a software mirror, a fault on the active disk, particularly accessing swap space would cause the kernel to panic, as kernel resources are responsible for the managing the mirror.

Depending on the hardware involved, a hardware mirror could have crashed the server when the controller driver tried to notify the kernel of the failed disk. (Likely causing another page fault, and multiplying the failure cycle as the kernel tries to sort itself out with i/o stacking up multiply)

Of course, this is all speculation on my part, but there are some pretty nasty possible modes of failure when swap gets corrupted on an I/O fault - even if it is mirrored.

Posts: 77 | From: Calgary | Registered: Aug 2003  |  IP: Logged
Phizzy_Phil
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Icon 1 posted October 20, 2005 05:00      Profile for Phizzy_Phil   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Thanks both,
Groggle you were right, its a software mirror and according to HP the crash is a "feature". If it didn't reboot, as you say swap could be corrupted and cause lots of nasty I/O errors. oh well live and learn...

Posts: 26 | From: Nottingham, UK | Registered: Oct 2005  |  IP: Logged


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