On Apr 7, 2011, at 3:00 PM, Garrett Cooper wrote: > On Thu, Apr 7, 2011 at 12:03 PM, Alexander Best <arun...@freebsd.org> wrote: >> On Thu Apr 7 11, Alexander Motin wrote: >>> Author: mav >>> Date: Thu Apr 7 08:17:53 2011 >>> New Revision: 220412 >>> URL: http://svn.freebsd.org/changeset/base/220412 >>> >>> Log: >>> Make ada(4) driver to control device write cache, same as ata(4) does. >>> Add kern.cam.ada.write_cache sysctl/tunable to control it alike hw.ata.wc. >> >> how hard would it be to support per device sysctls/tunables? i'd really like >> to >> do: >> >> kern.cam.ada.0.write_cache=0 (root fs) >> kern.cam.ada.1.write_cache=1 (/usr, /var, etc.) > > Does it really make sense to turn on write caching for one drive and > not the other(s)?
Think about /usr/obj or /tmp and ask that question again. Or any filesystem that's mounted that you don't really care about the contents of across a power cycle. If you have to recreate it, that's OK. In those cases, you may want the speed increase over safety that write_cache gives you. Or maybe you have a drive that's doing write caching correctly and one that doesn't. Warner _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
