From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: ReiserFS post-crash issues Date: Tue, 21 Sep 2004 08:01:19 -0700 Message-ID: <4150423F.3020804@namesys.com> References: Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Ash Cc: reiserfs-list@namesys.com FS operations are not persistent unless you fsync or wait long enough. That is the expected norm for unix fs design. Hans Ash wrote: >Hi > >I have been running a few tests on ReiserFS to check durability of >common filesystem operations. >For example, create a certain number of files and crash the machine >(poweroff) immediately after this. >On rebooting, check the number of files actually present on the >filesystem after log replay. > >Similarly, I tried for some other operations like rename, link and delete. >I am using a C program with open, rename and link system calls to >perform these operations respectively >and crashing the system using a network power switch immediately after >my C program finishes doing its stuff. >So the delay in-between completion of the operations and the machine crashing >should be, according to me, less than 1-2 seconds (which is the time >required to establish a telnet connection to the power switch) > >It seems that ReiserFS operations are not durable for most of the cases I tried. > >For file create, when tried with 50K, 100K and 1M files, I got >34224, 99492, and 998594 files respectively after system rebooted from the >crash. Similarly for operations like rename and link, the number of files >renamed or linked after reboot is less than what the filesystem reports prior >to the crash. > >Now introducing a fsync() after every open() call does solve the problem >but the performance degradation seen is very high. In fact, I did notice >the related discussion on the FAQ at namesys.com. > >Also, operations like rename, link and delete also seem to give problems. > >However, with other filesystems like XFS, I get much better results (almost >100% durability) on similar tests. > >I am using ReiserFS with linux kernel 2.6.7 > >Any comments/suggestions will be helpful. > >Thanks, >Ash > > > >