From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id 9D5597F3F for ; Mon, 30 Dec 2013 05:27:54 -0600 (CST) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay3.corp.sgi.com (Postfix) with ESMTP id 24E00AC003 for ; Mon, 30 Dec 2013 03:27:54 -0800 (PST) Received: from awesome.dsw2k3.info (awesome.dsw2k3.info [217.188.63.246]) by cuda.sgi.com with ESMTP id gqSlnyzDhj1ipBd6 (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Mon, 30 Dec 2013 03:27:48 -0800 (PST) Date: Mon, 30 Dec 2013 12:27:43 +0100 From: Matthias Schniedermeyer Subject: Re: [xfs_check Out of memory: ] Message-ID: <20131230112743.GA16889@citd.de> References: <201312270907.22638.arekm@maven.pl> <20131227224212.GK20579@dastard> <201312280020.39244.arekm@maven.pl> <20131229095033.GL20579@dastard> <52C0D281.7040704@hardwarefreak.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <52C0D281.7040704@hardwarefreak.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Stan Hoeppner Cc: Stor?? <289471341@qq.com>, Jeff Liu , xfs@oss.sgi.com On 29.12.2013 19:55, Stan Hoeppner wrote: > On 12/29/2013 3:50 AM, Dave Chinner wrote: > ... > > I think you are forgetting that developer time is *expensive* and > > *scarce*. This is essentially a solved problem: An SSD in a USB3 > > enclosure as a temporary swap device is by far the most cost > > effective way to make repair scale to arbitrary amounts of metadata. > > It certainly scales far better than developer time and testing > > resources... > > Now this is an interesting idea Dave. I hadn't considered temporary > swap. Would USB be reliable enough for this? I've seen lots problem > reports with folks using USB storage with Linux, random disconnections > and what not. It's certainly a problem with several variables. - Quality of USB-Stack (should be quite good nowadays, but there can always be (new) bugs) - Quality of SATA <-> USB(3) Chip - Quality of SSD itself And with Quality i mean everything from physical chip up to firmware. I'm not quite sure what happens when SWAP crapps out. I think it can be everything from "machine goes dead" down to "all programs with pages in swap are terminated". I've transfert quite a few TB over USB3 and i can say, it mostly works. But random disconnects happen and you can't really be sure which part is the problem as it only happens rarely. For e.g. currently i have a HDD that randomly but seldomly craps out in an USB3 enclosure, after coping a few hundert GB. The drive works flawlessly when connected directly by SATA to a (different) computer, at least i haven't had a failure after i moved the drive. Is it the drive, chip in enclose, firmware between HDD & enclosure not playing nice (like too high command timeouts on HDD side and too low on enclosure-sde), USB3 stack. Can't really tell. So: I would consides SWAP on a device connected via USB3 to be on the risky side. I would validate beforehand if that specific combination of xhci/enclosure chip/SSD survies a prolonged time of "high I/O stress". Like several days of full bandwidth/random I/O. -- Matthias _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs