- Site menu:
- Latest Discussions
- Latest Newswire
- Archives
- Submit Story
- Story HOWTO
- Syndicate
- E-mail Alerts
Benchmarking hardware RAID vs. Linux kernel software RAID
|
|
|
Comments (3)
Yeah, I use software raid on my fileserver (can't afford one of them fancy high end raid controllers anyway).
I also have an "old" Dell Poweredge 2500c I'm setting up for the church here that I switched over from hardware raid to software raid.
While hardware raid is probably faster and such, it's just not as flexible.
Maybe it's different with the $$$$$ controllers, but the raid on the Poweredge will only let you raid full disks.
I love software raid because I can raid pretty much anything I want in any way I want, like using a partition on a disk for part of an array, while leaving the rest of the disk for other use (I do this on my fileserver).
For example on my fileserver I have:
Standard mirror of 2 80GB disks.
And also
/dev/sdb is actually a 30GB disk, but I'm using 20GB for this array and the other 10GB as a separate partition.
And yes, I know that I could have just raided the complete disks together and then partitioned the md into 2 parts, but I didn't know that at the time, and this demonstrates the flexibility of software raid anyway.
And all of this is done with parts I have been given/have salvaged over the years (the server itself is an old Celeron 766 at the moment), except for the Promise Ultra133-TX2 controller for the raid disks and the Netgear Gigabit NIC (which will be replaced soon with an Intel Pro 1000 when I get around to swapping stuff out around the lan).
For example on my fileserver I have:
Quoting:
cthulhu ~ # mdadm --detail /dev/md0 /dev/md0: Version : 00.90.03 Creation Time : Fri Feb 8 20:00:17 2008 Raid Level : raid1 Array Size : 78148096 (74.53 GiB 80.02 GB) Used Dev Size : 78148096 (74.53 GiB 80.02 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 0 Persistence : Superblock is persistent
Update Time : Wed Jul 16 13:15:12 2008 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0
UUID : a1fc0d8b:f8e3241e:e78c31d9:d2cca1bc Events : 0.24
Number Major Minor RaidDevice State 0 8 1 0 active sync /dev/sda1 1 8 33 1 active sync /dev/sdc1
Standard mirror of 2 80GB disks.
And also
Quoting: cthulhu ~ # mdadm --detail /dev/md1 /dev/md1: Version : 00.90.03 Creation Time : Sat Feb 9 14:39:44 2008 Raid Level : raid0 Array Size : 40087296 (38.23 GiB 41.05 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistentStriping of 2 disk partitions.
Update Time : Wed Jul 16 13:13:06 2008 State : active Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0
Chunk Size : 64K
UUID : 10a51a9f:e8e3a488:0d5066c6:b7f82744 Events : 0.3
Number Major Minor RaidDevice State 0 8 17 0 active sync /dev/sdb1 1 8 49 1 active sync /dev/sdd1
/dev/sdb is actually a 30GB disk, but I'm using 20GB for this array and the other 10GB as a separate partition.
And yes, I know that I could have just raided the complete disks together and then partitioned the md into 2 parts, but I didn't know that at the time, and this demonstrates the flexibility of software raid anyway.
And all of this is done with parts I have been given/have salvaged over the years (the server itself is an old Celeron 766 at the moment), except for the Promise Ultra133-TX2 controller for the raid disks and the Netgear Gigabit NIC (which will be replaced soon with an Intel Pro 1000 when I get around to swapping stuff out around the lan).
Quoting:Maybe it's different with the $$$$$ controllers, but the raid on the Poweredge will only let you raid full disks.
Even my high-end expensive 3ware only RAIDs full disks. This can be a problem when you loose a disk and don't have a spare one of the exact same brand and model. If you use a different one, the number of blocks may be slightly different. Not a problem if the new disk is a few blocks larger, but if it's a few blocks smaller you're looking at shrinking and rebuilding your entire RAID array. That's one of the main reasons I went with software RAID back then. I don't have the money to buy more identical disks and keep them around as spares "just in case".
Post a comment
A free account is needed to post. Write your comment here first: your text is kept in this browser while you sign up or log in, and is waiting for you when you come back.
Your message:Markdown: **bold**, *italic*, [text](https://link), - lists, > quotes, $x^2$ for math. Formatting help
Sign up and post (it is free) or Log in and post
Software RAID has significant advantages over hardware RAID. The article only talks about performance and whether it justifies the cost of a hardware RAID card. You should not be looking just at the cost of the card but also about the cost of any future upgrades. If I had used hardware RAID it would have cost me $500 more to get a new server (either to get an expensive 3ware card that runs PCIe, or to get a more expensive T300 server that does have a PCI-X slot).