transaction-log memory mapped on AIX ?

[mike]

Environment: db2v7 on aix. 32-bit instance.

When db2v7 writes to the transaction log files (not during archival,
but when flushing logbuf), does it use MMAP on the log file or regular
system calls?

I'm assuming it uses regular system calls, but wonder if anyone can
verify.

[Ian]

mike wrote:

Environment: db2v7 on aix. 32-bit instance.

When db2v7 writes to the transaction log files (not during archival,
but when flushing logbuf), does it use MMAP on the log file or regular
system calls?

I'm assuming it uses regular system calls, but wonder if anyone can
verify.

Although I can't say for sure, I suspect it's dependent on the
DB2_MMAP_WRITE (and DB2_MMAP_READ) variables.

[mike]

Ian wrote:

mike wrote:

Environment: db2v7 on aix. 32-bit instance.

When db2v7 writes to the transaction log files (not during archival,
but when flushing logbuf), does it use MMAP on the log file or regular
system calls?

I'm assuming it uses regular system calls, but wonder if anyone can
verify.

Although I can't say for sure, I suspect it's dependent on the
DB2_MMAP_WRITE (and DB2_MMAP_READ) variables.

I should have stated in my original query that these variables
are both at their default v7 setting (ON) , so SMS and file-dms
container files are memory-mapped, but the question is whether
the txn-log would also use that technique.

[Ian]

mike wrote:

>
I should have stated in my original query that these variables
are both at their default v7 setting (ON) , so SMS and file-dms
container files are memory-mapped, but the question is whether
the txn-log would also use that technique.

Right, and my point was that if MMAP read/write are enabled (as they
are by default), DB2 would probably use the mechanism for I/O to the
txn log files.

I could be wrong, but that's my gut feeling (based on my knowledge that
enabling DB2_NT_NOCACHE would cause DB2 to open ALL files on a Windows
server with the no-caching attribute set).