[DRBD-user] PROTOCOL C

Lars Ellenberg Lars.Ellenberg at linbit.com
Fri Mar 19 16:15:28 CET 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


/ 2004-03-19 14:14:12 +0100
\ Benoit.Ropartz at alcatel.fr:
> Hi,
> 
> I try to know if data blocks are write or not to the local hard disk with
> protocol C when write order is completed (in application).

I don't understand what you ask here.

An application issues some IO request.
The request will be satisfied sooner or later.

If this was a WRITE request, the application can ask the kernel to
suspend this application until the request has reached stable storage.

With proto A, the application will resume operation as soon as the
block was send off to the local TCP stack, and reached the local disk.
B: when the block reached remote memory and local disk.
C: when the block reached BOTH local and remote disk.

If the application does not ask about "have my write requests
reached stable storage", no one will tell it about.
Such an application is badly written, or the data was of
throw-away type... I doubt there are any apps of this kind.

Thats it.

> If it's yes what is the role of open option file SYNC ?

Again I just don't understand what you are refering to.

	Lars Ellenberg



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