Sequential /random disk read and write %

[former_member253718]

Dear Experts ,

can some one guide me from where i can find the exact values over a period of months for sequential/random disk (Input/ouput) reads and writes , i have searched on st03n >> workload >> database there i can see no of sequential read and direct access , i could sum up these values and get the required values for read at least but when i compare them to the data i get from st04 it somehow does not match

for st04 i can see much more number of physical reads ,i am assuming the sum of sequential reads and #accesses from st03n should sum up to the physical read field from st04

can anyone please support

Best Regards,

Shubham Jain

[Former Member]

you can get the historical data in ST03 -> change mode to Expert mode --> workload --> total. Here you can see the data by Day/Week/Month.

[former_member253718]

Hi Sunil,

The question is not about historical data  , the question is from where i can get authentic data for disk input / output from architectural point of view if we want to redesign out hardware

there seems to be a difference between data in st04 and st03n maybe i am lookign at a wrong place.

Regards,

Shubham Jain

[Former Member]

In st04 you get the data since the DB started. and in ST03 you get the historic data by day/week/month wise.

[former_member253718]

Dear Sunil,

Thanks for your response , I get the difference between the data now. do you have any insights from where I can get the data for  sequential disk write and random disk write

in the entire AWR I cannot find the term sequential write .

I get from AWR the total disk I/O writes and Total Direct writes . I am not sure if the difference between these terms would be sequential write

Shubham jain

[fidel_vales]

hi,

you are confusing "things"

When SAP (SM50 or SM66, for example) you see the term "sequential read" that is different from Oracle "db file sequential read"

the first only indicates that the source code NOT requesting one row (SELECT SINGLE, SELECT UP TO 1 ROW or a SELECT specifiying all primary key fields with an equal)

The second indicates that ONE block has been requested to the disk.

The first does not indicate anything related to disk I/O, the second does not includes all disk I/O (direct reads, db file multiblock read ...)