> 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). > > 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: <http://www.fsl.cs.sunysb.edu/docs/joukov-phdthesis/thesis.pdf> Figures 9.7 and 9.8 also show profiles of the Linux RAID5 and RAIF5 operation under the same Postmark workload. Nikolai. --------------------- Nikolai Joukov, Ph.D. Filesystems and Storage Laboratory Stony Brook University - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
