1.To add live HA to PG, I transfer WAL of a database instance(Primary node) to another database instance (standby node) at real time, and keep startup alive in standby node to recovery WAL online,so that standby node can be a hot standby.
But I got some trouble. When standby node switch to primary mode to accept connections, of course after startup initilize the WAL and exit, the postgres process ereportERROR
when mdread function enter ERROR branch, and I got message like this "could not read block X of relation X/X/X: read only Xof X bytes". I spent two days to figure out what happened, but it is too hard.Please help me.

2. When restore data from a LIVE backup , I got message like "unexpected pageaddr %X/%X in log file %u, segment %u, offset %u" "WAL ends before end time of backup dump". It seems the WAL was
corrupted. I found the LSN where the error occured contained the wrong pageaddr, the pageaddr was 8K before it's real address.What was wrong?

2010-08-04



Richard

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  • Joshua D. Drake at Aug 3, 2010 at 4:40 pm

    On Wed, 2010-08-04 at 00:34 +0800, Richard wrote:
    1.To add live HA to PG, I transfer WAL of a database instance(Primary node) to another database instance (standby node) at real time, and keep startup alive in standby node to recovery WAL online,so that standby node can be a hot standby.
    But I got some trouble. When standby node switch to primary mode to accept connections, of course after startup initilize the WAL and exit, the postgres process ereportERROR
    when mdread function enter ERROR branch, and I got message like this
    "could not read block X of relation X/X/X: read only Xof X bytes". I
    spent two days to figure out what happened, but it is too hard.Please
    help me.
    What are you using to transfer the WAL?

    Did you read this chapter?

    http://www.postgresql.org/docs/8.3/static/continuous-archiving.html

    Sincerely,

    Joshua D. Drake

    >

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  • Robert Haas at Aug 3, 2010 at 4:46 pm
    On Tue, Aug 3, 2010 at 12:34 PM, Richard wrote:
    1.To add live HA  to PG, I transfer WAL of a database instance(Primary
    node) to another database instance (standby node) at real time, and
    keep startup alive in standby node to recovery WAL online,so that
    standby node can be a hot standby.
    But I got some trouble. When standby node switch to primary mode to accept connections, of course after startup initilize the WAL and exit, the postgres process ereportERROR
    when mdread function enter ERROR branch, and I got message like this "could not read block X of
    relation X/X/X: read only Xof X bytes". I spent two days to figure out what happened, but it is too hard.Please help me.

    2. When restore data from a LIVE backup , I got message like "unexpected pageaddr %X/%X in log file %u, segment %u, offset %u" "WAL ends before end time of backup dump". It seems  the WAL was
    corrupted. I found the LSN where the error occured contained the wrong pageaddr, the pageaddr was 8K before it's real address.What was wrong?
    Please see http://wiki.postgresql.org/wiki/Guide_to_reporting_problems

    I recently troubleshot a problem much like the one you describe in (2)
    and I believe in that case it was a bad disk subsystem that started
    failing writes and didn't tell PG. But it could also be caused by
    misconfiguration. Since you haven't given any details about your
    configuration or what steps you've tried to take to resolve the
    problem, it's pretty difficult to guess what's going on in your case.

    --
    Robert Haas
    EnterpriseDB: http://www.enterprisedb.com
    The Enterprise Postgres Company

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