From owner-freebsd-questions@freebsd.org Wed Sep 9 18:50:36 2015 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A31E59CDDD8 for ; Wed, 9 Sep 2015 18:50:36 +0000 (UTC) (envelope-from prvs=168719c8fe=vogelke@pobox.com) Received: from SCOTT-MAIL1.afnoc.af.mil (scott-mail1.afnoc.af.mil [132.3.41.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "SCOTT-MAIL1.afnoc.af.mil", Issuer "DOD CA-27" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 1A1BC1648 for ; Wed, 9 Sep 2015 18:50:35 +0000 (UTC) (envelope-from prvs=168719c8fe=vogelke@pobox.com) Received-PRA: neutral (us.af.mil: 131.9.254.133 is neither permitted nor denied by domain of pobox.com) client-ip=131.9.254.133; envelope-from=vogelke@pobox.com; helo=us.af.mil; Received-SPF: neutral (us.af.mil: 131.9.254.133 is neither permitted nor denied by domain of pobox.com) client-ip=131.9.254.133; envelope-from=vogelke@pobox.com; helo=us.af.mil; Received: from us.af.mil (unknown [131.9.254.133]) by SCOTT-MAIL1.afnoc.af.mil with smtp (TLS: TLSv1/SSLv3,256bits,DHE-RSA-AES256-SHA) id 2684_730b_aa4b2548_ccc9_4f3b_bbff_4c827e2577be; Wed, 09 Sep 2015 18:50:21 +0000 Received: from ([131.9.40.227]) by 52vejx-mr-002.us.af.mil with SMTP id 5X21FN1.184546828; Wed, 09 Sep 2015 13:50:14 -0500 Received: (qmail 6877 invoked by uid 100); 9 Sep 2015 18:50:14 -0000 From: "Karl Vogel" Date: Wed, 9 Sep 2015 14:50:14 -0400 To: freebsd-questions@freebsd.org Subject: Re: Storage question Message-ID: <20150909185013.GA5368@bsd118.area52.afnoapps.usaf.mil> Reply-To: vogelke+unix@pobox.com References: <55EF3D23.5060009@hiwaay.net> <20150908220639.20412cbd@gumby.homeunix.com> <55EF5409.8020007@yahoo.com> <55EFC2DA.3020101@hiwaay.net> <08B351DD-AA48-4F30-B0D6-C500D0877FB3@lafn.org> <55F02DC8.7000706@hiwaay.net> <20150909150626.5c3b99e5.freebsd@edvax.de> <55F031A0.40500@hiwaay.net> <55F0375D.4070608@FreeBSD.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55F0375D.4070608@FreeBSD.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-NAI-Spam-Flag: NO X-NAI-Spam-Threshold: 4.1 X-NAI-Spam-Score: -0.9 X-NAI-Spam-Version: 2.3.0.9393 : core <5424> : inlines <3769> : streams <1502533> : uri <2036413> X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Sep 2015 18:50:36 -0000 On Wed, Sep 09, 2015 at 02:42:53PM +0100, Matthew Seaman wrote: > Actually, ZFS's RAM requirements may not be as gargantuan as all that. > Despite its reputation for gobbling up all that's available and asking > for more, it doesn't have to be that way. What takes up the space are > the filesystem caches, and how much you need for those depends > absolutely on your usage patterns. I'm on a Solaris-11.1 system so this doesn't strictly apply, but with a little tweaking ZFS works pretty well with low memory: Environment: full X-Windows, Apache, dev stuff (compilers, etc.) Memory: 4Gb PC3-10600 Chipset: AMD 785G CPU: AMD Athlon(tm) II X2 B28 Processor, 3.4 GHz, 2MB L2 cache Disk: 500-GB 3.5" Drive 7,200 rpm, 16MB cache, 3.0 GB/s I have a second drive with a 32MB cache, and the performance improvement from the additional memory is significant. My boot settings are below; hope this helps. [Yes, I'd love more memory. It's a gov't site, I ordered it last Nov, and I'm sure it'll be here any day now.] -- Karl Vogel I don't speak for the USAF or my company Lois, I think people would prefer a knock to "Pants on". --Clark Kent chastising Lois Lane for her preferred way of entering a room on "Smallville". # ------------------------------------------------------------------------- # Prefetch is on by default, disable for workloads with lots of random I/O. # or if prefetch hits are less than 10%. set zfs:zfs_prefetch_disable = 1 # Seems to make scrubs faster. # http://serverfault.com/questions/499739/ set zfs:zfs_no_scrub_prefetch = 1 set zfs:zfs_top_maxinflight = 64 set zfs:metaslab_min_alloc_size = 4096 set zfs:zfs_scan_idle = 10 set zfs:zfs_scrub_delay = 1 # Enable no write throttling? If your drives can't keep up, you # can end up with a core dump, according to # http://hardforum.com/showthread.php?t=1742979 ## set zfs:zfs_no_write_throttle = 1 ## set zfs:zfs_write_limit_override = 1 # http://dan3lmi.blogspot.com/2012/10/solaris-zfs-tuning-cache-flushes.html # Looks like it's more for storage arrays or JBODs. ## set zfs:zfs_nocacheflush = 1 # https://rageek.wordpress.com/2012/07/09/strickly-limiting-zfs-arc-cache-size/ # Keep ARC size to about 1/4th memory set zfs:zfs_arc_max = 1048576000 set zfs:zfs_arc_min = 1048576000 # -------------------------------------------------------------------------