From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: where is the journal kept? Date: Tue, 16 Aug 2005 22:51:54 -0700 Message-ID: <4302D07A.40804@namesys.com> References: <20050815115310.GA28630@tranquility.scriptkitchen.com> <20050815125025.GA29390@tranquility.scriptkitchen.com> <43009184.2080201@namesys.com> <200508150812.40382.pat@patdouble.com> <4300A603.2050602@namesys.com> <4300D240.7010109@namesys.com> <4302458E.9070604@namesys.com> <430268F4.8020100@slaphack.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <430268F4.8020100@slaphack.com> List-Id: Content-Type: text/plain; charset="us-ascii" To: David Masover Cc: Shawn Rutledge , "Vladimir V. Saveliev" , reiserfs-list@namesys.com David Masover wrote: > Shawn Rutledge wrote: > > >On 8/16/05, Hans Reiser wrote: > > >>Reiser4 does a very nice job of packing the tree tightly, which is > >>independent of seeks. Ditto for compression plugin. > >>He merely needs to ignore some code, he is not harmed by it. If he > >>wants to write a new block allocator, sure, why not, we have allocator > >>plugins yes? His will just be simpler..... > > > >But the most important thing is to reduce the number of writes as low > >as possible. > > > Something Reiser4 does very well. If you have enough RAM, it's possible > to avoid any reads/writes at all -- given enough RAM, it behaves as a > ramdisk, which is why I wish I knew how to tell Gentoo to *not* mount > tmpfs over /dev. > > One other thing you might try is disabling the write-twice behavior. > Currently, if you've got a huge, fairly well-sorted file that you're > making lots of tiny writes to, such as a database, it makes sense to > write twice to keep the file from getting fragmented. But, > fragmentation isn't nearly as much an issue on truly random-access > media, so you'd want the default small-file behavior to be used > everywhere -- first write the data to the new location, then atomically > update the pointer to it as you deallocate the old location. > > Am I right about this? I'm not feeling very lucid today... Yes, but there is not a lot of write twice for most usage patterns.... Hans