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ratio of synchronous reads for bufferpool

P: n/a
hello,

admin guide says that
pool_data_p_reads - pool_async_data_reads will give me number of
physical reads that were performed synchronously (that is, physical
data page reads that were performed by database manager agents).

I assume then pool_data_p_reads should give total value of all reads
( synchronous + asynchronous )
i see values for pool_async_data_reads more than pool_data_p_reads in
my snapshots for bufferpools

i am taking delta every 10 minutes

i am confused
can anyone please explain?

regards,
jagdip singh

Mar 9 '07 #1
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5 Replies


P: n/a
db2admin wrote:
hello,

admin guide says that
pool_data_p_reads - pool_async_data_reads will give me number of
physical reads that were performed synchronously (that is, physical
data page reads that were performed by database manager agents).

I assume then pool_data_p_reads should give total value of all reads
( synchronous + asynchronous )
i see values for pool_async_data_reads more than pool_data_p_reads in
my snapshots for bufferpools

i am taking delta every 10 minutes

i am confused
can anyone please explain?

regards,
jagdip singh
pool_async_data_reads gives the async reads for _all types of tablespaces_
pool_data_p_reads gives the reads for regular and large tablespaces, i.e.
excluding temp. ts's.
The correct formula to calculate synchronous physical reads therefor should
be:

pool_data_p_reads + pool_temp_data_p_reads - pool_async_data_reads

Check these pointers:
http://publib.boulder.ibm.com/infoce...c/r0001236.htm
http://publib.boulder.ibm.com/infoce...c/r0001244.htm

HTH.

--
Jeroen
Mar 10 '07 #2

P: n/a
On Mar 10, 4:00 pm, "The Boss" <use...@No.Spam.Please.invalidwrote:
db2admin wrote:
hello,
admin guide says that
pool_data_p_reads - pool_async_data_reads will give me number of
physical reads that were performed synchronously (that is, physical
data page reads that were performed by database manager agents).
I assume then pool_data_p_reads should give total value of all reads
( synchronous + asynchronous )
i see values for pool_async_data_reads more than pool_data_p_reads in
my snapshots for bufferpools
i am taking delta every 10 minutes
i am confused
can anyone please explain?
regards,
jagdip singh

pool_async_data_reads gives the async reads for _all types of tablespaces_
pool_data_p_reads gives the reads for regular and large tablespaces, i.e.
excluding temp. ts's.
The correct formula to calculate synchronous physical reads therefor should
be:

pool_data_p_reads + pool_temp_data_p_reads - pool_async_data_reads

Check these pointers:http://publib.boulder.ibm.com/infoce...ic/com.ibm.db2....

HTH.

--
Jeroen
thanks a lot
i really appreciate the help

Mar 12 '07 #3

P: n/a
On Mar 12, 6:05 pm, "db2admin" <jag...@gmail.comwrote:
On Mar 10, 4:00 pm, "The Boss" <use...@No.Spam.Please.invalidwrote:
db2admin wrote:
hello,
admin guide says that
pool_data_p_reads - pool_async_data_reads will give me number of
physical reads that were performed synchronously (that is, physical
data page reads that were performed by database manager agents).
I assume then pool_data_p_reads should give total value of all reads
( synchronous + asynchronous )
i see values for pool_async_data_reads more than pool_data_p_reads in
my snapshots for bufferpools
i am taking delta every 10 minutes
i am confused
can anyone please explain?
regards,
jagdip singh
pool_async_data_reads gives the async reads for _all types of tablespaces_
pool_data_p_reads gives the reads for regular and large tablespaces, i.e.
excluding temp. ts's.
The correct formula to calculate synchronous physical reads therefor should
be:
pool_data_p_reads + pool_temp_data_p_reads - pool_async_data_reads
Check these pointers:http://publib.boulder.ibm.com/infoce...ic/com.ibm.db2........
HTH.
--
Jeroen

thanks a lot
i really appreciate the help
I could not find pool_temp_data_p_reads for bufferpool snapshot data
I am on DB2 V8 + FP 11
How would you determine the same for a bufferpool ?

Mar 13 '07 #4

P: n/a
On Mar 13, 1:42 pm, "db2admin" <jag...@gmail.comwrote:
On Mar 12, 6:05 pm, "db2admin" <jag...@gmail.comwrote:
On Mar 10, 4:00 pm, "The Boss" <use...@No.Spam.Please.invalidwrote:
db2admin wrote:
hello,
admin guide says that
pool_data_p_reads - pool_async_data_reads will give me number of
physical reads that were performed synchronously (that is, physical
data page reads that were performed by database manager agents).
I assume then pool_data_p_reads should give total value of all reads
( synchronous + asynchronous )
i see values for pool_async_data_reads more than pool_data_p_reads in
my snapshots for bufferpools
i am taking delta every 10 minutes
i am confused
can anyone please explain?
regards,
jagdip singh
pool_async_data_reads gives the async reads for _all types of tablespaces_
pool_data_p_reads gives the reads for regular and large tablespaces, i.e.
excluding temp. ts's.
The correct formula to calculate synchronous physical reads therefor should
be:
pool_data_p_reads + pool_temp_data_p_reads - pool_async_data_reads
Check these pointers:http://publib.boulder.ibm.com/infoce...ic/com.ibm.db2........
HTH.
--
Jeroen
thanks a lot
i really appreciate the help

I could not find pool_temp_data_p_reads for bufferpool snapshot data
I am on DB2 V8 + FP 11
How would you determine the same for a bufferpool ?
I am sorry for previous post
I collected snapshot data using snapshot table function which does not
give values for pool_temp_data_p_reads
I looked at manual for all possible values for bufferpool snapshot and
it does include values for pool_temp_data_p_reads
I do not know why snapshot table function does not include column for
pool_temp_data_p_reads

Mar 13 '07 #5

P: n/a
That's fun!!

I compared the fields of the "Select * from TABLE( SNAPSHOT_BP(..."
with the fields contained in the db2 command line snapshot. There are
missing some more fields!

There is NO info about any TEMP - 4 values missing (log./phys. & data/
index).
Also missing:
- Asynchronous index read requests
- No victim buffers available
- Vectored IOs
- Pages from vectored IOs
- Block IOs
- Pages from block IOs
- Physical page maps
- Tablespaces using bufferpool
- Pages left to remove
- Current size
- Post-alter size

May be there is still some homework for IBM to do? I think some values
are interesting (e.g. TEMP, Blocked/vectored IO)

Mar 14 '07 #6

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