Sync I/O?

[ericfjchen]

This is HP-UX + XP256. I am a little confused about I/O path on XP256.
While a process requests an I/O, the entire process is OS-> HBA-> cache memory-> shared memory? Pls kindly explain how a sync I/O complete a process.

Thanks

Eric

[Victor BERRIDGE]

Hi,
From what point of vue?
For HP-UX, after an I/O request is done lets say write, depending how your FS is configured (raw devices or all the other options of vxfs) will lead to different behaviour... once passed the HBA, the XP256 will most time reply "done", and will do the job in background because it was first loaded in its cache...
What are you looking for?

All the best
Victor

[ericfjchen]

1. For block device, what kind of writing path A sync I/O done?
2. Besides cache memory, does XP256 have shared memory? If yes, what is it main function?

Thanks

Eric FJ