On Wed, 9 Mar 2005 peter.greis@xxxxxxx wrote: > Greetings All, > > I have been lurking for a while.... I recently put together a raid 5 > system (Asus K8NE SIL 3114/2.6.8.1 kernel) with 4 300GB SATA Seagate > drives (a lot smaller than the bulk of what seems to be on this list!). Size isn't important :) > Currently this is used for video and mp3 storage, being Reiser on LVM2. > > So a couple of questions: > > Bonnie++ to test, but with which parameters ? Also, I have seen the > mount option "nolargeio=1" for reiser, but not a lot of information on > the impact in raid systems. > > Any thoughts ? Why LVM2? Are you taking snapshots, or expecting to re-size the array? I just could never work out why I needed yet another layer of software between the application and the disk platter. There may well by a good reason for it - I did look into LVM some 18 months ago when I was looking at snapshot solutions though, but it was hideously slow (or appeared to be) after I'd taken a snapshot. (My intention was to tape dump from the snapshots, and provide a 'yesterday' & 'the day before' type things. I now use rsync for that - takes time to make the snapshot, but accesses to it are no slower than accessing the live aray. I know nothing about reiser either, so can't help there, I'm afraid, however, XFS has some real-time facilities which might be useful for streaming data, but again, it's not something I've looked into. Anyway - if you are streaming big files, you want nothing more than time dd to test the speed of the thing. Bonnie++ will limit the size of a single file to 2GB (and write multiple 2GB files if you specify a bigger size) and you'll get an indication of how busy the CPU is when it's writing & reading. Your drive will have between 55 and 65MB/sec of head bandwidth, so anything better than that is a bonus, athough the 3114 will have all 4 ports on the same PCI bus, so thats going to be your bottleneck. If you want more speed, you might want to try to reconfigure it in a RAID-10 way, but then you'll only get 2 disks worth of storage rather than the 3 in a RAID-5 setup. Also test streaming over LAN if thats what you are doing - if it's just a 100Mb LAN, then all your disk system needs to be able to do is 12MB/ses and anything more is a bonus. And do check your disks regularly, although I don't think current version of smartmontools fully supports sata under the scsi subsystem yet... Good luck, Gordon - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
