Software RAID in Linux

[Zach]

Who else has played with it? I have software RAID 5 going for a webserver I'm building (contact me if you're willing to be a test subject for a discount), and am going to have some fun with it tonight..

I've waited for the parity to sync, so it's time to unplug a drive and see what happens.

 

[Workin']

I've used it with RAID 0, but not RAID 5. It worked great for me, but it was somewhat different than what you are doing. Oh well.

 

[SUOrangeman]

I'm thinking about going RAID in my next system and am very interested in your setup/notes for Linux. Right now, assume RAID 0.

TIA.

-SUO

 

[andri]

Software RAID is actually quite simple to set up. RAID-HOWTO has pretty clear instructions.

 

[Workin']

It's even easier than the HOWTO says. I used Red Hat 6.2 and used Disk Druid to set up my partitions. Basically you set up whatever partitions you need, as I recall I used a 5MB /boot partition and a 64MB swap partition, and used the rest for /. But if you have 2 additional drives that you can use just set the partition type to RAID and then there is an option to create the RAID set where you just pick the partitions you want to include in the volume. It's easier than it sounds.

 

[soho]

kestion...

can you add a disk to the Raid 5 array in Linux? For instance you have a 3 disk raid 5 array and want to increase the disk size by adding another drive. Is it possible?

 

[Damaged]

I've set it up. Works just fine.

Thanks but no thanks on a discount on some web space. I have over 90GB already riding on a co-lo (dual OC-12)and another 90 some odd GB that I could setup on my home comps on my DSL line.

However...if you would like some help, just ask.

 

[Zach]

What would help cost me?

Also, has anyone figured out if you can add disks to RAID 5 arrays? Mine just finished 'syncing' it's parity today, which would seem to imply that it would be possible to add a drive and get that parity going for another lot of data, and I don't see why moving stripes would be a problem. Do hardware RAID adapters do this?

 

[StuckMojo]

to my knowledge (which is not that extensive), most hardware raid controlers do not let you add volumes on the fly.

my bud sells network attached storage from network appliance, and one of the big features of his hardware is being able to add drives like that.

however, since its software raid...maybe. have you checked the docs?

 

[MrSuperstar]

So how is the speed of Software raid in linux? I'm considering setting up RAID 5 on a dual pentium pro 180.. will that work ok? Or does it take more speed? If it does, I can always get a cheap duron or something...

 

[soho]

Sure you can add drives to hardware raid on the fly. If that's your friend's product's key selling point he is going to have stiff competition. Perc raid controllers in Dell machines do just that, Pull out the nonfunctioning drive, insert the new drive, and then if auto rebuild is enabled you don't need to do anything else.

I wasn't familiar with Linux's software raid. So is it possible to add an additional drive to the array?

 

[Zach]

We mean add drives, not replace them. Like I have 4 9.1 gig SCSI's, and it'd be nice to add four externals when I run out of room... I don't know of a decent controller that doesn't rebuild after a drive failure? You can have the spare-disks in software raid too...

As for speed, definetly better than a single drive! It's on a celeron 400 too, nothing amazing. How can you test disk access / transfer speeds in linux? Without X too.