> > the ZIL is always there in host memory, even when no > synchronous writes > are being done, since the POSIX fsync() call could be > made on an open > write channel at any time, requiring all to-date > writes on that channel > to be committed to persistent store before it returns > to the application > ... it's cheaper to write the ZIL at this point than > to force the entire 5 sec > buffer out prematurely >
I have a question that is related to this topic: Why is there only a (tunable) 5 second threshold and not also an additional threshold for the buffer size (e.g. 50MB)? Sometimes I see my system writing huge amounts of data to a zfs, but the disks staying idle for 5 seconds, although the memory consumption is already quite big and it really would make sense (from my uneducated point of view as an observer) to start writing all the data to disks. I think this leads to the pumping effect that has been previously mentioned in one of the forums here. Can anybody comment on this? TIA, Thomas This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
