Re: [expert] reiser fs ? (was: Unexplained crashes)
Hi, Tony, I'm not sure of the benefits of ReiserFS other than journalling, but I can give you a quick overview of journalling itself: Basically, journalling is a way of ensuring that the file system never (in theory, at least :) ) becomes internally inconsistent. For instance, if you were running Win9x with [VFAT, FAT32] or Linux with e2fs and you poked your reset button, the part of the file system that is in charge of writing everything to the hard drive wouldn't get a chance to flush it's buffers, make sure all of the file allocation tables/inodes were pointing at valid files, and so on. When the system comes back up, you will have to sit through a scandisk in Win9x or an e2fsck in Linux while the OS goes through and sorts out all of the potential problems with the file system and fixes them. Now with Reiser FS (NTFS for WinNT/2000 and BeFS for BeOS are journalled as well), prior to each file system write to the hard drive, the system basically does a pre-write to a special file called a journal file that says, "I intend to write the following information to file FOO: xx". Once the entry is verified to be in the journal, the system applies the change to the actual file and finally removes the entry from the journal and marks it as being completed. This way, the system has two choices in case of a catastrophic shutdown: if there are any entries in the journal file that are marked as incomplete but valid, the system can apply those updates without compromising the integrity of the file system, and it will do so. However, if the system was interrupted in the process of writing to the journal file itself, the entry will be invalid and will be deleted without being applied. Either way, the actual file system itself remains valid and internally consistent. This is why, if you are running one of the three file systems mentioned above, if you hit the reset button, when the OS comes back up, there will be no file system check of any sort (in ReiserFS you'll see a message to the effect of "applying N changes". Granted, this was a bare bones overview, (and may not be completely accurate: I've never dug into the source for any of the file systems in question), but this is at least the concept. Hope this helps, Brian - Original Message - From: "Tony McGee" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, 18 August, 2000 09:34 Subject: [expert] reiser fs ? (was: Unexplained crashes) Can anyone give me the 10c guide to what the reiserfs provides that ext2 doesn't? I've heard the term journalling thrown about but have no idea what that means. I always hate when the bandwagon is a mile down the road before I've even noticed it. :) Tony On Fri, 18 Aug 2000, Roan pushed some tiny letters in this order: Thanks, that took care of the problem! I just reseated all the cables, memory SIMMs, and the CPU. The box has been up and running since yesterday afternoon with no hiccups. Now I get to re-install and use ReiserFS. :)
Re: [expert] reiser fs ? (was: Unexplained crashes)
On Sat, 19 Aug 2000, Tony McGee wrote: Can anyone give me the 10c guide to what the reiserfs provides that ext2 doesn't? I've heard the term journalling thrown about but have no idea what that means. I always hate when the bandwagon is a mile down the road before I've even noticed it. :) Rather than waste everyone's time with a long description, one of the main ReiserFS sites, www.devlinux.org/namesys, has a very good description as well as a lot of documentation for the product. Tony -- Regards, Ellick Chan [EMAIL PROTECTED] Aug 19
Re: [expert] reiser fs ? (was: Unexplained crashes)
IN a nutshell Tony the Reiser FS is basically the ext2 FS with a few important modifications. One of which is the fact that the file system keeps a journal entry for the entire FS so that in the event of an unclean unmount, if there is such a thing...but you get the idea... the FS can recover better than a regular ext2 FS given that it knows where everything is/was...is supposed to be because it's got a system of journalized entries to map the FS with. Phew! Frankly I'm VERY impressed with the way the ext2 FS in Mandrake handles as compared to RedHat 6.0, 6.1, and 6.2. It recovers FAR more gracefully than the other three I just mentioned. By the way, I used to use RedHat on my machine. That is until I met Mandrake and for me at least the choice is crystal clear. Mandrake All the way! Mark Tony McGee wrote: Can anyone give me the 10c guide to what the reiserfs provides that ext2 doesn't? I've heard the term journalling thrown about but have no idea what that means. I always hate when the bandwagon is a mile down the road before I've even noticed it. :) Tony On Fri, 18 Aug 2000, Roan pushed some tiny letters in this order: Thanks, that took care of the problem! I just reseated all the cables, memory SIMMs, and the CPU. The box has been up and running since yesterday afternoon with no hiccups. Now I get to re-install and use ReiserFS. :)
Re: [expert] reiser fs ? (was: Unexplained crashes)
I believe that you're talking about ext3, which is ext2 with journaling added. AFAIK it is not yet included with Mandrake. ReiserFS is a completely new filesystem with an underlying structure that is similar to a database. Unlike most Unix/Linux filesystems, ReiserFS does not use inodes. I am using it because it is supposedly optimized to handle large numbers of small files (like a typical mail server). On a normal Unix filesystem (like ext2) with a lot of small files, you will often run out of inodes before you run out of space. Of course, you can reconfigure things to support more inodes, but it's a pain to do so. I have been using ReiserFS on three systems for over a month. One is a webserver, one is for development, and one is a mail server (the hardware is identical). It works flawlessly on all systems, except for the mail server. The mail server fails mysteriously every 9-10 days. I can't say for certain that the problem is caused by ReiserFS, since I can't find any error messages in the system logs. However, it seems to be the most likely culprit. The system doesn't crash, but I can't run any new programs (which requires the use of the filesystem to retrieve them from disk). X still works and the system will echo chars on the command line. However, since I can't load a new program (like 'shutdown') I am forced to hit the reset button to get back to normal. After that, it reboots quickly and with no apparent loss of data. It's annoying to be forced to reboot every few days (reminds me of Windows NT) and I'd like to figure out the problem. If I can't find any clues to the cause, I'm going to try plugging the drive into a different motherboard (maybe it's a hardware-related problem). I have not been able to detect any kind of pattern to the failures and the time between them is so long that it is difficult to troubleshoot. Jeff At 03:23 PM 8/18/00 -0400, you wrote: IN a nutshell Tony the Reiser FS is basically the ext2 FS with a few important modifications.
RE: [expert] reiser fs ? (was: Unexplained crashes)
(skipping the journalling since others answered) In theory, ReiserFS is faster for certain types of disk operations involving small files. Most FS's use fixed blocks that have wasted space at the end. In a FS with 2KB block size a 1 byte file still takes up 2KB. ReiserFS uses that space efficiently (read about it on their website; URL in a previous msg in this thread). ReiserFS disks with a lot of small files should get more usable space and faster access than with ext2. ReiserFS also has plugins that would allow DB developers, for example, to optimize the on-disk storage methods to improve data access and retrieval. It's all really geeky. I love it. Matthew Zaleski -Original Message- From: Tony McGee [mailto:[EMAIL PROTECTED]] Sent: Friday, August 18, 2000 11:35 AM To: [EMAIL PROTECTED] Subject: [expert] reiser fs ? (was: Unexplained crashes) Can anyone give me the 10c guide to what the reiserfs provides that ext2 doesn't? I've heard the term journalling thrown about but have no idea what that means. I always hate when the bandwagon is a mile down the road before I've even noticed it. :) Tony On Fri, 18 Aug 2000, Roan pushed some tiny letters in this order: Thanks, that took care of the problem! I just reseated all the cables, memory SIMMs, and the CPU. The box has been up and running since yesterday afternoon with no hiccups. Now I get to re-install and use ReiserFS. :)
