Hardware RAID -how complicated?

I got a laptop, so I'm turning my old computer into a Samba file server (not sure what distro yet). I've decided to get an additional IDE HDD which I'll RAID (level 1) with the existing one. I'm planning on using this PCI controller card to do so.

My question is, since this is a hardware RAID (unless I'm mistaken), are there any special configurations I need to do to get Linux to work with this, or should it just work transparently when I hook all the hardware up? Is there anything I'll need to do to the Kernel?

I'd hesitate to answer this categorically(the only person that can offer that is someone who's used the same card :) ), but I'm pretty sure it should be plug n play with a recent distro. The card has been around for a while, you can see the rather old linux distros it lists as supported(RH 7.x, Suse 7.x), so that's usually a good sign.

You're more likely to have chipset compatibility issues than OS problems, I suspect.

DT

Be careful, unless you get a high end RAID card you will get a controller that masquerades as hardware RAID but is actually software. Unless you get a RAM specification with it and a pricetag to match it won't really work. I just got a SATA Raid controller for about €35. It's excellent, supports up to 4 sata devices on 6 ports. But although you configure the card in a bios like screen, it is still software raid. Suse 10 identified it as such and warned me. I can see the two disks seperately. If this was hardware RAID this would be impossible.

Anyway moral of the story, software raid in linux is pretty good. you don't need a special controlller, though seperate channels would be nice. Even if your distro goes belly up, you can still use the software raid as the partitions are tagged as raid even before the formatting. If the controller you're looking at says it supports only RAID 1, 0 or 1+0 (10) then it is most likely not hardware raid. Hardware should support a minimum of RAID 5.

Have you looked at LVM? If you are just looking at combining to discs it's great. Plus you can add to it and subtract (?). There is no redundancy but if a disc fails the others are unaffected. I have two 320GB disks in an LVM volume on this server as I type.

Good luck with it, if you have any more questions I can answer, I hope I can help.

EDIT- Sorry edit is not working for me ....

I just clocked your link. I see that has mirror, striping, both and JBOD (Just a bunch of disks). By the looks of it, and certainly at that price the raid supported is not hardware raid. This link should confirm for you. Also from the error I got the other day, kernel 2.4 had some tolerance for this type of configuration but 2.6 did not include it. Linux software raid or LVM should do what you need.

Thanks a bunch - I sincerely appreciate your help.

I'm actually wanting to mirror two harddrives for backup/redundancy, so LVM is not likely what I want...unless it can support mirroring?

How much money would I likely be looking at for a true hardware PCI RAID card (that would work well with Linux)? And do you happen to know of any off the top of your head?

If I did go with this card and did a software RAID, would I be able to dual-boot and everything work exactly the same under both Windows and Linux?

I found 2 hardware (I think) RAID controllers. Which is likely better?

one
two

Both cards are quite suitable, the Highpoint one is both cheaper and comes with a higher rating - I'd go with that. It's a lot to invest in but Hardware RAID is excellent in my opinion. As for the dual boot - Software RAID is not bootable directly (or at least it can have prohibitively awkward and time consuming setups) so you will need to boot from a different disk or partition the discs accordingly. If you want to fully mirror the disks you will be able to see them in Linux, pretty much any distro as it's a standard kernel module that looks after it. However Windows is out, not just because of formatting though. You could say use half of each disc (same sectors etc) and have them in a software RAID, but windows is not capable of the same unless you use either third party software or I believe some of the Win32 server OSes support it. Downside is it is not as resilient as a linux soft raid. If you need to reinstall windows you will most likely lose the setup and the data with it.

In this case you are back to Hardware RAID. Good news here is that

• It is completely transparent to all OSes
• It is bootable
• Seperately configurable through a 'BIOS'
• You also get the option of RAID 5

I hope that's of some use. The opinion on the cards above is just opinion you may want to confirm that yourself.

I'm trying to load SuSE 10.1 On to a RAID 1 array using a DPT PM3754U2 hardware SCSI RAID card (with an onboard Intel i960). It has 4 EDO slots, and 1 RAM SIMM. I think it's 16 megs, but I'm not sure. I can set of the array, and SuSE recognizes it as a hard drive, but when I go to load, it starts out fine, with some 500+ files to load off of CD1. Somewhere around 100 files left (400 loaded), it chokes and crashes. I tried it about 5 or 6 times, and every time it crashes on a different file, but it's always in the same neighborhood of about 100 files left. :mad:

Any ideas what may be going on? Not enough EDO? RAM configured wrong? :???:

Oh, and btw - I tried it with several different drives. Same result.

Not sure myself. I ended up installing Ubuntu server on the computer from scratch and it's worked ever since.

I would google: +cardname +suse to see if there are any known incompatibilities or issues.

Did it require any special drivers? Do you have the latest ones installed? If it does require some, I'd look on the web site or even contact the author.


Chad

As I inderstand it, and any correction to the contrary would be welcome, a smart card like this doesn't need a RAID driver, because it masqurades as a single SCSI drive. You still need a SCSI driver, just like on any SCSI card, but that comes with the distro. It certainly didn't need or ask for any drivers in order to recognize what was installed.

I suspect that it has to do with the onboard RAM, that it thinks that it has more than it really does, and runs out, but I can't verify that. I just thought that someone has seen this before.

My other alternative is to use one of those dumb IDE RAID cards, but the picture that I'm getting is that earlier kernals had support for them and for some reason, it was dropped in more recent kernels. If there's a way to make one of them work without hacking things to bits, I'd be interested, but I don't want a system that will take a day to build. I really like my SuSE, but if there's a distro out there that supports RAID without making you jump through a bunch of hoops, I may switch.