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Re: TRAP: FailedAssertion("!((itemid)->lp_flags & 0x01)",

From: Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: TRAP: FailedAssertion("!((itemid)->lp_flags & 0x01)",
Date: 2005-10-28 04:26:31
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Thu, 27 Oct 2005, Tom Lane wrote:

> "Jim C. Nasby" <jnasby(at)pervasive(dot)com> writes:
> > On Wed, Oct 26, 2005 at 09:29:23PM -0400, Tom Lane wrote:
> >> Could you send me the whole file (off-list)?
> > Ok, will send URL as soon as I have it from client.
> Well, the answer is that there's nothing wrong with that index except
> that four consecutive pages near the end (32K total) have been zeroed
> out :-(


> Bottom line is that index searches probably ought to have some
> non-Assert defenses against zeroed-out pages.  Obviously we can't
> expect to catch every flavor of data corruption, but this particular
> one has been seen before...

Definately. I've seen faulty hardware somehow zero blocks where I would
have expected random data. I wonder if we can test with PageIsNew(), which
is very inexpensive. The question is: what do we do when we detect this?

> BTW, Jim, any thoughts about how the index got corrupted?  Have you
> had any crashes on that machine lately?

Have spoken with Jim on IRC, he says that there have been several crashes
recently due to a faulty disk array. I guess the zeroing could be an
outcome of the faulty disk. I wonder if the crash the faulty disk resulted
in could have been caused some where around mdextend() where we create a
zero'd page but before we could have written out the initialised page.

If this happened 4 times in a row it could account for the problem. It
does seem a bit unlikely thought.

That being said, is there any reason where don't extend the file with a
PageInit()'d block instead of a zero'd file?



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Subject: Re: TRAP: FailedAssertion("!((itemid)->lp_flags & 0x01)", File: "nbtsearch.c", Line: 89)
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Subject: Re: TRAP: FailedAssertion("!((itemid)->lp_flags & 0x01)", File: "nbtsearch.c", Line: 89)

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