large Mass Data I/O Managing

[Henry_3]

Hello there!

My system is in SDE(20CPU/20GB Memory, 11.i)

Usually I make a sort job by SYNC Sort tool which services festly in memory.

When SYNC processing, Buffer Case hit rate is lowing and then I am recommanded using direct I/O, that means not using buffer case.

But I have a question. If I didn't use Buffer Cashe, How can OS get data fastly without knowing the adress of data ?

Does anybody have a experience using the SYNC sort tool or lage mass data I/O managing?

I wil wait many helps.

Thank you very much.