Re: Hardware RAID5 vs Software RAID5
"Matthew Bowie" <[email protected]>
| Newsgroups | gmane.org.user-groups.nmlug |
|---|---|
| Message-ID | <[email protected]> |
I've used both Linux software and hardware RAID, but had a failure on neither so can't give personal experience on recovery. As far as flexibility, I love Linux RAID. One of the things I like about it is that you can RAID just a partition instead of a whole drive. Plus you can stack RAID on top of LVM or LVM on top of RAID, or RAID on top of RAID if you wish. Also, with software RAID, the drives don't even need to be remotely similar (although you'll want access times to be close and rpms to be the same or you'll limit yourself to the slowest drives performance). So from a flexibility standpoint, software RAID wins hands down. If it's doing A LOT of hard drive access and it's a really slow computer, then CPU utilization might become an issue. Doing a 13GB copy from a software RAID 0 drive to itself shows CPU utilization spikes of up to 40% (avg of about 20%) on an AMD 64 3700+. So it's got to read from, assemble, disassemble, and write out the data across the RAIDed partitions. Which was always acceptable performance for me, especially with the speed increase in reads I was getting. Below is an example using 2 7200 RPM SATA drives w/ 1 partition on each in a RAID 0 config. # hdparm -tT /dev/md1 /dev/md1: Timing cached reads: 1524 MB in 2.00 seconds = 760.81 MB/sec Timing buffered disk reads: 324 MB in 3.01 seconds = 107.79 MB/sec As far as an OS for NAS, you'll wanna stick w/ something light. Don't need a pretty desktop or a ton of stuff for a NAS system. Debian would be a good option, as a base install w/ just NFS, SAMBA, FTP, and Webmin would probably be < 300MB. Of course Gentoo is always an option, but you probably don't want to wait hours to install a distro just to serve some files and get a marginal (at best) performance increase. Especially since either your drives or the network are going to be the bottleneck, not the OS. Another thing you can look at is DRBD (http://www.drbd.org). Basically RAID 1 over the network. Since it can work w/ LVM partitions, it's what I plan to use for redundant storage on two HP585 G4's running Xen with Windows and Linux guest OS's. Anyways, just my $.02. Which is probably about what it's worth :) -- Matthew Bowie Programmer/IT Consultant [email protected] _______________________________________________ NMLUG mailing list [email protected] http://www.nmlug.org/mailman/listinfo/nmlug