From owner-freebsd-fs@FreeBSD.ORG Sat Oct 20 07:37:58 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id A36ABE03 for ; Sat, 20 Oct 2012 07:37:58 +0000 (UTC) (envelope-from daniel@digsys.bg) Received: from smtp-sofia.digsys.bg (smtp-sofia.digsys.bg [193.68.3.230]) by mx1.freebsd.org (Postfix) with ESMTP id 2070D8FC19 for ; Sat, 20 Oct 2012 07:37:56 +0000 (UTC) Received: from surfer-172-30-97-1-proxy.surfnet.iacbox ([193.43.158.229]) (authenticated bits=0) by smtp-sofia.digsys.bg (8.14.5/8.14.5) with ESMTP id q9K7UIAj002727 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Sat, 20 Oct 2012 10:30:25 +0300 (EEST) (envelope-from daniel@digsys.bg) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\)) Subject: Re: Memory consumption after turning off dedup From: Daniel Kalchev In-Reply-To: <44510CBA-2D95-4BDF-8AEE-61727760321C@wimsey.us> Date: Sat, 20 Oct 2012 10:30:18 +0300 Content-Transfer-Encoding: quoted-printable Message-Id: <28A26432-EB80-41DF-82B2-B1D8F998D9A5@digsys.bg> References: <44510CBA-2D95-4BDF-8AEE-61727760321C@wimsey.us> To: David Wimsey X-Mailer: Apple Mail (2.1499) 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: Sat, 20 Oct 2012 07:37:58 -0000 The only way I am aware of to get rid of the DDT (what is consuming = memory) is to turn dedup off, then copy all the data in again -- if you = have space, you could copy within the same zpool, then remove the old = data. Maybe it doesn't remove all the DDT entries, such as for metadata, = but at least most of it will be gone. Turning off dedup only prevents = deduplication of data you write after that act. Daniel On Oct 20, 2012, at 10:18 AM, David Wimsey wrote: > I've had dedup on for a while and everything was good until the feeble = machine I have as a file server couldn't deal with the memory = requirements of dedup. I solved the problem by adding more RAM, = imported the pools on the machine and turned off dedup. I had a ratio = of less than 2x, and the main savings were on virtual machine disks = which I want maximum performance for. >=20 > Does the memory consumption due to the DDT go away when you turn dedup = off or do I need to do a send/recv on it? >=20 > I assume that once the block is deduced and written to disk its not = really any different than a blocks associated with a snapshot, is that = correct? >=20 > I also assume that there is no performance penalties on reads, only = writes since it (with dedup on) has to check the dedup table to see if = it is a duplicate, is that correct? >=20 > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"