On Fri, 4 Sep 2009, Scott Meilicke wrote:
I only see the blocking while load testing, not during regular usage, so I am not so worried. I will try the kernel settings to see if that helps if/when I see the issue in production.
The flipside of the "pulsing" is that the deferred writes dimish contention for precious read IOPs and quite a few programs have a habit of updating/rewriting a file over and over again. If the file is completely asynchronously rewritten once per second and zfs writes a transaction group every 30 seconds, then 29 of those updates avoided consuming write IOPs. Another benefit is that if zfs has more data in hand to write, then it can do a much better job of avoiding fragmentation, avoid unnecessary COW by diminishing short tail writes, and achieve more optimum write patterns.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
