From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Boldi Subject: Re: [ANNOUNCE] RAIF: Redundant Array of Independent Filesystems Date: Fri, 15 Dec 2006 08:02:55 +0300 Message-ID: <200612150802.55396.a1426z@gawab.com> References: <200612132257.24399.a1426z@gawab.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1256" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Nikolai Joukov Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org List-Id: linux-raid.ids Nikolai Joukov wrote: > > Nikolai Joukov wrote: > > > We have designed a new stackable file system that we called RAIF: > > > Redundant Array of Independent Filesystems. > > > > Great! > > > > > We have performed some benchmarking on a 3GHz PC with 2GB of RAM and > > > U320 SCSI disks. Compared to the Linux RAID driver, RAIF has > > > overheads of about 20-25% under the Postmark v1.5 benchmark in case of > > > striping and replication. In case of RAID4 and RAID5-like > > > configurations, RAIF performed about two times *better* than software > > > RAID and even better than an Adaptec 2120S RAID5 controller. > > > > I am not surprised. RAID 4/5/6 performance is highly sensitive to the > > underlying hw, and thus needs a fair amount of fine tuning. > > Nevertheless, performance is not the biggest advantage of RAIF. For > read-biased workloads RAID is always slightly faster than RAIF. The > biggest advantages of RAIF are flexible configurations (e.g., can combine > NFS and local file systems), per-file-type storage policies, and the fact > that files are stored as files on the lower file systems (which is > convenient). Ok, a I was just about to inform you of a three nfs-branch raif which was unable to fill the net pipe. So it looks like a 25% performance hit across the board. Should be possible to reduce to sub 3% though once RAIF matures, don't you think? > > > This is because RAIF is located above > > > file system caches and can cache parity as normal data when needed. > > > We have more performance details in a technical report, if anyone is > > > interested. > > > > Definitely interested. Can you give a link? > > The main focus of the paper is on a general OS profiling method and not > on RAIF. However, it has some details about the RAIF benchmarking with > Postmark in Chapter 9: > > > > Figures 9.7 and 9.8 also show profiles of the Linux RAID5 and RAIF5 > operation under the same Postmark workload. Thanks! -- Al