Ubuntu Linux RAID: Hardware or software?

[BusyDoingNothing]

I started my Ubuntu build with an Adaptec 2610SA (Dell CERC 1.5/6ch). Card worked fine, got it up and running. I have 2x WD 500GB Green drives in a RAID 1 for backup, and 3x Hitachi 1TB drives intended for a RAID 5 for data. I come to find out the card doesn't like 1TB or larger drives. Ugh. Back to eBay it goes.

The card was touted as an inexpensive hardware RAID solution that works well in Linux. I liked the sound of that. It's useless to me now that I can't use 1TB drives. I'm at a crossroads now. Should I seek out another hardware solution, or should I just go software RAID? Are there any drawbacks to software? It's a home server, so performance isn't exactly my biggest concern, stability and reliability is.

Does anyone have any recommendations either way? I'm going to need some piece of hardware regardless (either a RAID controller or SATA controller) because my board only has 2 SATA ports and I need at least 5.

Any recommendations would be appreciated.

 

[Nothinman]

I always tend to lean towards software RAID. Linux software RAID is a lot more flexible than most hardware solutions and the performance is on par or better. I don't think you can really go wrong with Linux software RAID and LVM on top.

 

[Gooberlx2]

Yep, software RAID + LVM on linux works very well. Fast, solid, reliable.

 

[Emulex]

i'd do raid-Z in software given those type of drives.

 

[sub.mesa]

Adaptec 2610SA seems to be a PCI card. That's kind of bad when using software RAID; especially RAID5. RAID is powerful as it can communicate parallel by issuing different I/O to each physical disk. The downside of PCI is that the other requests will lag behind the first one, creating a latency that hurts performance.

In this time where a $40 motherboard provides 6 full bandwidth Serial ATA, you should not have to resort to PCI for your software RAID array. I looked for a review on the smaller 4-port version, this is what the review said:

"Below them, they placed two Silicon Image Sil3112A chips and a flash BIOS chip, while Intel 80302 processor and two memory chips reside in the right part of the PCB."

That kind of is an ugly solution i would say. The SiI-3112 chips are buggy as hell too; i wouldn't want to serve my important array through such a troubled controller chip. One other thing:

I have 2x WD 500GB Green drives in a RAID 1 for backup, and 3x Hitachi 1TB drives intended for a RAID 5 for data.

Please know that RAID can never replace a backup. Either you have a backup, or you don't. Even the most redundant arrays won't protect you from damage that falls outside its protection and without backup you're just as screwed.

For consumers, i would recommend running 2 normal non-RAID disks over a single RAID1 array. RAID1 is very useful for servers to prevent going down, but for consumers it takes just as much as space as a backup but RAID protects against much fewer dangers than a backup is able to.

Same goes for RAID5, although not all your data may be irreplaceable. I do recommend setting aside stuff that you can't afford to lose, and invest in a good backup solution that DOES protect you when hell breaks loose.

 

[BusyDoingNothing]

sub.mesa, thanks for the detailed info. You're right, I can probably find a pretty inexpensive mobo, but that would entail getting a new CPU and new memory also, and that would up the price. I guess I'd end up spending a decent amount on a card anyway. Any recommendations on an inexpensive cpu/mobo combo for this?

Regarding backup, I completely understand. I plan on having all my critical data on the RAID 1, which will probably do nightly incremental backups from my desktop, then I'll likely do a weekly backup of that RAID to an external hard drive.

 

[Emulex]

yeah make sure you take into consideration site recovery.

theft. fire. vandalism (virus).

you don't want to expose your only off-site backup say if someone pwns your machine and corrupts everything during its only copy. or corrupt ram or whatever.

i find machines with ECC ram (bus/etc) about 100X more stable than the machines without them (all running XP).