From owner-freebsd-fs@FreeBSD.ORG Sun Jun 9 14:09:07 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 06B80CC1 for ; Sun, 9 Jun 2013 14:09:07 +0000 (UTC) (envelope-from marck@rinet.ru) Received: from woozle.rinet.ru (woozle.rinet.ru [195.54.192.68]) by mx1.freebsd.org (Postfix) with ESMTP id 6F4601AD5 for ; Sun, 9 Jun 2013 14:09:06 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by woozle.rinet.ru (8.14.5/8.14.5) with ESMTP id r59E950f090752; Sun, 9 Jun 2013 18:09:05 +0400 (MSK) (envelope-from marck@rinet.ru) Date: Sun, 9 Jun 2013 18:09:05 +0400 (MSK) From: Dmitry Morozovsky To: Jeremy Chadwick Subject: Re: /tmp: change default to mdmfs and/or tmpfs? In-Reply-To: <20130609124603.GA35681@icarus.home.lan> Message-ID: References: <20130609124603.GA35681@icarus.home.lan> User-Agent: Alpine 2.00 (BSF 1167 2008-08-23) X-NCC-RegID: ru.rinet X-OpenPGP-Key-ID: 6B691B03 MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (woozle.rinet.ru [0.0.0.0]); Sun, 09 Jun 2013 18:09:05 +0400 (MSK) Cc: freebsd-fs@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Jun 2013 14:09:07 -0000 On Sun, 9 Jun 2013, Jeremy Chadwick wrote: [back to second part] [and snip a lot here too] > Where someone stated that excessive ARC usage on ZFS had an indirect > effect on tmpfs. r233769 to stable/9 may have fixed this, but given the > history of all of this "juggling" of Feature X causing memory exhaustion > for Feature Y, and in turn affecting Feature Z, all within kernel space, > I really don't know how much I can trust all of this. > > One should probably review the FreeBSD forums for other posts as well, > as gut feeling says there's probably more there too. .. that's why I'm trying to discuss this in public (maybe wrong list had been chosen, perhaps -stable@ would fit a bit more) -- to share knowledge, opinions and other related stuff ;) > In closing: > > If you want to make bsdinstall ask/prompt the administrator "would you > like to use tmpfs for /tmp?", then I'm all for it -- sounds good to me. > But doing it by default would be something (at this time) I would not be > in favour of. I just don't get the impression of stability from tmpfs > given its track record. (Yes, I am paranoid in this regard) Agree at most. > *** -- For example I personally have experienced strange behaviour when > ZFS+UFS are used on the same system with massive amounts of I/O being > done between the two (my experience showed the ZFS ARC suddenly limiting > itself in a strange manner, to some abysmally small limit (much lower > than arc_max)). In this case, I can only imagine tmpfs making things > "even worse" given added memory pressure and so on. For our backup server, which uses rather huge 24*2T raidz2 and periodically synced on eSATA UFS, I sometimes seen speed drops, but nothing really bad. It's stable/9 with 16G of RAM though, perhaps on systems where RAM is tighter the situation could be much worse... -- Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] [ FreeBSD committer: marck@FreeBSD.org ] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------