From: Achilleas Mantzios <achill@matrix.gatewaynet.com>
Organization: Dynacom Tankers Mgmt
To: =?utf-8?q?C=C3=A9dric_Villemain?= <cedric.villemain.debian@gmail.com>
Subject: Re: pgsql 8.3.3 "Invalid page header" leads to "FATAL: segment too
	big"
Date: Thu, 22 Apr 2010 17:18:51 +0200
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Cc: "pgsql-admin@postgresql.org" <pgsql-admin@postgresql.org>
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	<g2ie94e14cd1004220653g29d54c30pacdfafea3a7493c@mail.gmail.com>
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=CE=A3=CF=84=CE=B9=CF=82 Thursday 22 April 2010 16:53:05 =CE=BF/=CE=B7 C=C3=
=A9dric Villemain =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:
> 2010/4/22 Achilleas Mantzios <achill@matrix.gatewaynet.com>:
> > Hello,
> > i have this serious problem in one of our remote vessels. (comm is done=
 by minicom to the remote satelite modem)
> > I think that this server was under some sort of constant resets or hard=
ware failures.
> > Initially,i had this problem:
> > ERROR: =C2=A0invalid page header in block 672720 of relation "pg_toast_=
125716009"
> >
> > This toast table corresponds to a table named "mail_message",
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Table "public.mail_message"
> > =C2=A0Column =C2=A0 | =C2=A0 =C2=A0 =C2=A0 Type =C2=A0 =C2=A0 =C2=A0 =
=C2=A0| =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 Modifiers
> > -----------+-------------------+---------------------------------------=
=2D-------------------
> > =C2=A0msgno =C2=A0 =C2=A0 | mail_msgno_domain | not null default nextva=
l('mail_msgno_sequence'::regclass)
> > =C2=A0msgsource | bytea =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 |
> > Indexes:
> > =C2=A0 =C2=A0"mail_message_key" PRIMARY KEY, btree (msgno)
> >
> > (obviously the TOAST table serves the msgsource varlena) the contents o=
f which is not of vital importance.
> > I tried, REINDEXING, with no success, and after that, i tried resetting=
 the said block on disk as per this
> > suggestion by Tom here: http://old.nabble.com/invalid-page-header-td119=
81154.html
> >
> > i found the oid of the table:
> > SELECT tableoid,1 from pg_toast.pg_toast_125716009 order by chunk_id LI=
MIT 1
> > =C2=A0tableoid =C2=A0| ?column?
> > -----------+----------
> > =C2=A0125716013 | =C2=A0 =C2=A0 =C2=A0 =C2=A01
> >
> > (and just to verify)
> > SELECT relname from pg_class where oid=3D125716013;
> > =C2=A0 =C2=A0 =C2=A0relname
> > --------------------
> > =C2=A0pg_toast_125716009
> >
> > Then i did: (as i said i do not need the contents of msgsource - yet th=
e contents of msgno are vital)
> > dd if=3D/dev/zero of=3D/usr/local/var/lib/pgsql/data/base/125714957/125=
716013 seek=3D672720 bs=3D8192 count=3D1
>=20
> segment have 1.1GB size maximum. You have to catch in what segment the
> faulty block is, and reajust the block value from the error report to
> the real one in the good segment.
>=20

Thanx,
Taking a look at /usr/local/src/postgresql-8.3.3/src/backend/storage/smgr/m=
d.c
i see the the error comes from function mdnblocks

if (nblocks > ((BlockNumber) RELSEG_SIZE))
                        elog(FATAL, "segment too big");

That means, that some segment file is bigger than RELSEG_SIZE
At least in my system:
#define BLCKSZ   8192
#define RELSEG_SIZE (0x40000000 / BLCKSZ)
So, any segment file cannot be bigger than RELSEG_SIZE blocks (or 2^30 byte=
s =3D 1GB)

Currently i dont have any access to the machine but tomorrow i will check t=
he file sizes.

Can anyone shed some light as to some method of identifying all the segment=
 files of a table?
The first one has the same name as the tableoid.=20
How about the subsequent segments?

> >
> > However, after that, unfortunately i get constant postgresql server res=
tarts with:
> > FATAL: =C2=A0segment too big
> > server closed the connection unexpectedly
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0This probably means the server terminated ab=
normally
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0before or while processing the request.
> > The connection to the server was lost. Attempting reset: Succeeded.
> >
> > Is there anything i can do to savage the situation?
> >
> > (one of) the hard part here is that i dont have neither physical nor ne=
twork access to the server
> > (only ultra expensive unreliable satellite comms)
> >
> > Thanks for any hints...
> >
> > --
> > Achilleas Mantzios
> >
> > --
> > Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org)
> > To make changes to your subscription:
> > http://www.postgresql.org/mailpref/pgsql-admin
> >
>=20
>=20
>=20


=2D-=20
Achilleas Mantzios