From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id E0BDE1381F3 for ; Tue, 17 Sep 2013 09:43:00 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id D10EEE0BC8; Tue, 17 Sep 2013 09:42:55 +0000 (UTC) Received: from mail-qe0-f44.google.com (mail-qe0-f44.google.com [209.85.128.44]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id B93F0E0BB2 for ; Tue, 17 Sep 2013 09:42:54 +0000 (UTC) Received: by mail-qe0-f44.google.com with SMTP id 3so3566505qeb.3 for ; Tue, 17 Sep 2013 02:42:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=0MkO7PJRgHXKXVwukF3POi+OZ+TM91BmOY16sF1MoFE=; b=vi1S4VLNLATOkcRPA1IQ2Q9bG1WuAfa1ZM0+m/wsSM4UbYDiBO7JBDFpKuIth3RnD5 HyKSpI7q2bzxB9RVKlySgKzIVSxUnSLYj02+1SLTdSMQBaN/hspqTTmSIq44AzIs2HNC kjka08vPpHmYW1oGJqhU4D6ol29QICiJxiMDbFxy1nOgf7SjnA2tkcVIWvLIShTAX1T1 vu/z9FqOHDF2r069ZxdIUHmerNnZvOqa58SiQK4Wj7Mj+g7/6AA2fuwu+We/RoFoXzQG uCrfR5pbyrd2Et1cMvZpbQHdLN0TrusAUIqz8t7fs+4DOO6dC9OhiO/fRP+uFLV/S1fK OiUg== Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 X-Received: by 10.224.125.2 with SMTP id w2mr4936308qar.46.1379410973870; Tue, 17 Sep 2013 02:42:53 -0700 (PDT) Received: by 10.140.25.83 with HTTP; Tue, 17 Sep 2013 02:42:53 -0700 (PDT) In-Reply-To: References: Date: Tue, 17 Sep 2013 02:42:53 -0700 Message-ID: Subject: Re: [gentoo-user] ZFS From: Grant To: Gentoo mailing list Content-Type: text/plain; charset=ISO-8859-1 X-Archives-Salt: cb20fd04-e6ae-41b6-9616-5e0df624af72 X-Archives-Hash: 749d7b39cf043b34d68971b482779e25 >> It looks like there are comprehensive ZFS Gentoo docs >> (http://wiki.gentoo.org/wiki/ZFS) but can anyone tell me from the real >> world about how much extra difficulty/complexity is added to >> installation and ongoing administration when choosing ZFS over ext4? > > Very very minimal. So minimal, in fact, that if you don't plan to use > ZFS as a root filesystem, it's laughably simple. You don't even have > to edit /etc/fstab I do plan to use it as the root filesystem but it sounds like I shouldn't worry about extra headaches. >> Performance doesn't seem to be one of ZFS's strong points. Is it >> considered suitable for a high-performance server? >> >> http://www.phoronix.com/scan.php?page=news_item&px=MTM1NTA > > Go directly to this post: > http://phoronix.com/forums/showthread.php?79922-Benchmarks-Of-The-New-ZFS-On-Linux-EXT4-Wins&p=326838#post326838 > > Notice how ZFS won against ext4 in 8 scenarios out of 9. (The only > scenario where ZFS lost is in the single-client RAID-1 scenario) Very encouraging. I'll let that assuage my performance concerns. >> Besides performance, are there any drawbacks to ZFS compared to ext4? > > 1. You need a huge amount of RAM to let ZFS do its magic. But RAM is > cheap nowadays. Data... possibly priceless. Is this a requirement for deduplication, or for ZFS in general? How can you determine how much RAM you'll need? > 2. Be careful when using ZFS on a server on which processes rapidly > spawn and terminate. ZFS doesn't like memory fragmentation. I don't think I have that sort of scenario on my server. Is there a way to check for memory fragmentation to be sure? > For point #2, I can give you a real-life example: > > My mail server, for some reasons, choke if too many TLS errors happen. > So, I placed "Perdition" in to capture all POP3 connections and > 'un-TLS' them. Perdition spawns a new process for *every* connection. > My mail server has 2000 users, I regularly see more than 100 Perdition > child processes. Many very ephemeral (i.e., existing for less than 5 > seconds). The RAM is undoubtedly *extremely* fragmented. ZFS cries > murder when it cannot allocate a contiguous SLAB of memory to increase > its ARC Cache. Did you have to switch to a different filesystem on that server? - Grant