From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: POHMELFS high performance network filesystem. Transactions, failover, performance. Date: Thu, 15 May 2008 02:10:09 +0100 Message-ID: <20080515011009.GA28687@shareable.org> References: <4829E752.8030104@garzik.org> <20080513205114.GA16489@2ka.mipt.ru> <20080514135156.GA23131@2ka.mipt.ru> <20080514143105.GB14987@shareable.org> <20080514150052.GA15826@2ka.mipt.ru> <20080514213251.GB23758@shareable.org> <20080514220252.GA14378@2ka.mipt.ru> <20080514222837.GF23758@shareable.org> <20080514224519.GA3739@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sage Weil , Jeff Garzik , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Evgeniy Polyakov Return-path: Received: from mail2.shareable.org ([80.68.89.115]:37507 "EHLO mail2.shareable.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752247AbYEOBKS (ORCPT ); Wed, 14 May 2008 21:10:18 -0400 Content-Disposition: inline In-Reply-To: <20080514224519.GA3739@2ka.mipt.ru> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Evgeniy Polyakov wrote: > > It's possible that implementing server cloud protocol _and_ simple > > client protocol may be more work than just server cloud protocol. I'm > > not sure. Thoughts welcome. > > Well, getting that client protocol is mostly ready, and its design > allows infinite (blah!) extensions and extremely (blah!) flexible > processing, we are close to just difficult server one :) That's what I thought when I had my system working fine with just one server. The client was very simple. :-) Since, I learned that my clients need to have parts of the complex server protocol for fast, safe transactions (think ACID (or ACI)) over relatively slow links, especially with multiple servers. Also, efficiently recovering from a link/server failure, when clients have large zero-latency caches (using leases), appears similar to the synchronising protocol between recovering servers. But, on the bright side, these things are only necessary for performance in scenarios you might not encounter or care about :-) I'm finding it's a really interesting but large problem. -- Jamie