Re: [Dovecot] linux 2.4 vs 2.6 kernel
We were posed with the same dilemma, but it was due to the need to stick with RHEL supplied packages (ReiserFS does not come with RHEL) that we stayed with ext3. Our old production mail server, running our in-house flavour of Linux, was based on the 2.4 kernel with ReiserFS.
We load tested Dovecot with maildir under RHEL3 (2.4 kernel) using ext3 and found it was unable to standup to our requirements. In part this was due to an inordinate imap-login / pop-login processes being created and hanging around under RHEL3. Using RHEL4 (2.6 kernel), we found we were able to handle the required load - this is the configuration we went live with. Processes ended cleanly too (result of the improved schedular and how it interacted with our IBM x445 and its NUMA architecture?) and the I/O issues seemed to have been resolved - ext3 was fine.
Subject: Re: [Dovecot] linux 2.4 vs 2.6 kernel From: Marc Perkel marc@perkel.com Date: Mon, 18 Jul 2005 18:33:54 -0700
CC: dovecot@dovecot.org
Curtis Maloney wrote:
Marc Perkel wrote:
Actually - yes. Same problem. But the solution is to use the Reiser Filesystem. It doesn't have the ext3 problem.
Now, I don't want to start a religious war, but...
Ext2 has the advantages that 1) it can fall back to ext2 in recovery cases, and 2) because of that, it has all the well-tested ext2 recovery tools available.
People I know who've used Reiser say it's wonderfuly fast, but if it corrupts, well... save your time, and go straight to restoring your backups.
Also, take a look at the tune2fs options. I understand -O dir_index will set it to use a b-tree index for faster handling of large directories.
-- Curtis Maloney cmaloney@cardgate.net
I've been using it for 5 years and it works great. It specifically eliminates the speed problems of Maildir where you have thousands of files in a single directory. And it has infinite inodes so you never run out of them. Reiser is ideal for email systems.
dovecot mailing list dovecot@dovecot.org http://dovecot.org/cgi-bin/mailman/listinfo/dovecot
Actually Redhat does support Reiser. When you install you have to type "linux reiserfs" on the command line to get the reiser options.
On Tue, 19 Jul 2005, Marc Perkel wrote:
Actually Redhat does support Reiser. When you install you have to type "linux reiserfs" on the command line to get the reiser options.
They "let" you install reiserfs, but if you ask for support they'll tell you to FOAD. Don't bother opening any bugzilla, if it has the word 'reiserfs' in it anywhere it will be instantly closed WONTFIX.
Redhat is promoting ext3 hard, which is understandable since they are bankrolling ext3 and see reiserfs as a competitor.
-Dan
Dan Hollis wrote:
On Tue, 19 Jul 2005, Marc Perkel wrote:
Actually Redhat does support Reiser. When you install you have to type "linux reiserfs" on the command line to get the reiser options.
They "let" you install reiserfs, but if you ask for support they'll tell you to FOAD. Don't bother opening any bugzilla, if it has the word 'reiserfs' in it anywhere it will be instantly closed WONTFIX.
Redhat is promoting ext3 hard, which is understandable since they are bankrolling ext3 and see reiserfs as a competitor.
-Dan
Perhaps. But if they don't get a tree into Ext3 they can promote it till hell freezes over and it's still going to be slow on directories with a large number of files.
You know what surprises me is that someone doesn't merge Netware into Linux. Netware was light years ahead of all Linux systems 20 years ago and I don't know if Linux will ever catch up. The had not only bTrees but transaction tracking that allowed any number of pending groups of transactions to be cleanly backed out if they fail to complete. But - i'm not going to go there because that would start a religious war. ;)
On Tue, 2005-07-19 at 16:01 -0700, Marc Perkel wrote:
Perhaps. But if they don't get a tree into Ext3 they can promote it till hell freezes over and it's still going to be slow on directories with a large number of files.
You haven't been reading the thread have you. Ext3 has had btree directories for more than 3 years. Its been mainstream kernel for a substantial time, and probably enabled by default on filesystem create for 2 years.
Nigel.-- [ Nigel Metheringham Nigel.Metheringham@InTechnology.co.uk ] [ - Comments in this message are my own and not ITO opinion/policy - ]
Marc Perkel wrote:
Actually Redhat does support Reiser. When you install you have to type "linux reiserfs" on the command line to get the reiser options.
From my understanding, this was true up to RHEL3 In RHEL4 / CentOS4 you can't do this anymore.... Reiser is simply not supported.... RH say this is because reiser doesn't support SELinux I'm not sure about Fedora
MT
Michael Tibben wrote:
Marc Perkel wrote:
Actually Redhat does support Reiser. When you install you have to type "linux reiserfs" on the command line to get the reiser options.
From my understanding, this was true up to RHEL3 In RHEL4 / CentOS4 you can't do this anymore.... Reiser is simply not supported.... RH say this is because reiser doesn't support SELinux I'm not sure about Fedora
MT
Really! Wow - that's bizzare! Fedora Core 4 supports it. I'm running it so I know first hand.
Really! Wow - that's bizzare! Fedora Core 4 supports it. I'm running it so I know first hand.
Yup, resier has been pulled from the RHEL kernel... However CentOS actually provide a custom kernel that put features like reiser back into the kernel that RH have taken out...
MT
participants (5)
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Dan Hollis
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Marc Perkel
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Michael Tibben
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Nigel Metheringham
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Paul Vatta