Hi All,



Who would believe that a modify of an isam table could stall an
installation? All the connections went mutex with Mutex: SCS
kdb_semaphore



What the hell is a kdb_semaphore...?



The installation is elderly and is running II 2.6/0604 (int.lnx/00) +
p12166.



The table was isam non unique on a single element key (integer not null
not default). The table has a 2k page size. There are no long columns,
no funnies like decimal or money, just integers, varchars and a date or
two. No secondary indexes.



The errlog shows things like:

E_DM93A7_BAD_FILE_PAGE_ADDR Page 400878 in table
candidate_addr_audit, owner: ascend, database: ascend, has an incorrect
page number: 0. Other page fields: page_stat 00000000, page_log_address
(00000000,00000000), page_tran_id (0000000000000000). Corrupted page
cannot be read into the server cache.



I've found that if I alter the table to isam/8k pages the problem goes
away. Ditto if I alter to btree/2k pages.



That's been a fun way to spend a day.



Martin Bowes

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Marty,

Most of the kdb_semaphore mutex problems seem to be related to running
out of file descriptors. You can use the "lsof -p <PID>" command to
list all the file descriptors in use for a process - when running this
modify how does that figure relate to your "open files" limit?

John

________________________________

From: info-ingres-bounces (AT) kettleriver...ting (DOT) com
[mailto:info-ingres-bounces (AT) kettleriverconsulting (DOT) com] On Behalf Of
Martin Bowes
Sent: Tuesday, 5 May 2009 11:11 PM
To: Ingres and related product discussion forum
Cc: Michael Lay
Subject: [Info-Ingres] More ways to stall an installation



Hi All,



Who would believe that a modify of an isam table could stall an
installation? All the connections went mutex with Mutex: SCS
kdb_semaphore



What the hell is a kdb_semaphore...?



The installation is elderly and is running II 2.6/0604 (int.lnx/00) +
p12166.



The table was isam non unique on a single element key (integer not null
not default). The table has a 2k page size. There are no long columns,
no funnies like decimal or money, just integers, varchars and a date or
two. No secondary indexes.



The errlog shows things like:

E_DM93A7_BAD_FILE_PAGE_ADDR Page 400878 in table
candidate_addr_audit, owner: ascend, database: ascend, has an incorrect
page number: 0. Other page fields: page_stat 00000000, page_log_address
(00000000,00000000), page_tran_id (0000000000000000). Corrupted page
cannot be read into the server cache.



I've found that if I alter the table to isam/8k pages the problem goes
away. Ditto if I alter to btree/2k pages.



That's been a fun way to spend a day.



Martin Bowes