Software RAID in Linux

Okay, today I got my tax return, a wonderful 800 Euros and I just went and got myself another 40gb HD to play around with RAID. And I was wondering..

a) How does one go about doing this? - Ender tells me that kernel software RAID will be much faster than my Hacked Promise RAID controller, so I would like to go with that.

b) How to NOT mess up my perfect LFS system when I go and do whatever it is I do ?
(A full backup on my server is possible if that's easier.)

c) One would like to go RAID 0+1 (if I recall the name correctly) - 2x40GB = 80gb FFM (Fucking Fast Mode )

[Killer_Penguin]

Ok,

A) since you are on LFS, head over to www.linuxdoc.org and check out thier software raid how-to. There are a few things that need to be in your kernel and whatnot.

B) I would suggest that you use mondo ( http://www.mondorescue.org ) to do a complete system backup to tape/cdr/whatever so that you can restore it directly to a new raid setup. The joy of mondo (;

C) 0+1 would require a boatload of disks. that's stripping + mirrored, so, atleast 2 disks to stripe across, them mirrored over to 2 more disks.... I'm thinking that you want to just stripe them for speed, and not worry about redundancy? If so, that's just Raid level 0, 0 == no redundancy, but stripped for speed.

One little gotcha, Linux can only boot from a mirror set, (raid 1) it can't boot from raid 0 or 5, so what I did was make a 50meg /boot partition, and leave it alone, while / and the rest of my partitions are raided.

I now have RAID 0 on MDK, but I can't for my life figure out how the fsck to make partitions on the little 80gb fucker.

no partitions means no LFS... and life without LFS will just be to hard to bear., I tried using LVM since from what I could read it would be like this:

RAID0 makes one partition or DiskDrake complains:
That one partition makes one large LVM volume:
That LVM volume makes partition babies.

But LVM won't fucking work, it fails with pvcreate, making a zero byte volume on my RAID0 array, totally screwing my HDs.

Oh and I decided to redo LFS, since I had various little problems with my 3.2 setup, which 3.3 should fix

[Killer_Penguin]

I now have RAID 0 on MDK, but I can't for my life figure out how the fsck to make partitions on the little 80gb fucker.

no partitions means no LFS... and life without LFS will just be to hard to bear., I tried using LVM since from what I could read it would be like this:

RAID0 makes one partition or DiskDrake complains:
That one partition makes one large LVM volume:
That LVM volume makes partition babies.

But LVM won't fucking work, it fails with pvcreate, making a zero byte volume on my RAID0 array, totally screwing my HDs.

Oh and I decided to redo LFS, since I had various little problems with my 3.2 setup, which 3.3 should fix

Fuck diskdruid... You are a LFS dude, do it manual.

Use fdisk to create some equal size partitions, then use them in /etc/raidtab to create raid devices. Start the raid device, then make your file system on /dev/md0 or 1 or whatever.

The how-to at www.linuxdoc.org was very helpfull when I did it first.

[Stix]

I just did this a couple of days ago on a RH7.1 box..Raid 0 with a separate /boot partition (not included in the stripe set) using a couple of older UW scsi drives. It worked out well for me, no redundancy but the increase in I/O was worth the effort. KP's (err..ender's) advice is, as usaual, right on. The software raid How-To is the place to start. I also found this site http://linas.org/linux/raid.html to be infomative also.

LC, your KDE3 screen shots look very good btw. And It's pretty cool that Ralinx came back

thx Stix, long time no see.

I FINALLY got it working... I hope.. Well it only took 9 reinstalls and a few mokings on #LJR.
But now I have RAID0 working with 2 main partitions and a bootable setup.

Oh the big shameful act... I installed WIndows solely to run a HD test program to see if my new HD was faulty - which is was partly.

So tomorrow will be LFS install day, wait, no.. I'm stuck in Drake for a few days I think.

[Stix]

Oh the big shameful act... I installed WIndows solely to run a HD test program to see if my new HD was faulty - which is was partly.

LOL...Not to fear, we all have to do things we don't really want to do sometimes... :-/ I'm glad the raid setup is working for though. Next is playing around with SAN's and NAS systems..Hehehe


sorry the quote got messed up

-- edit --

Fixed the quote for you, it drove we nuts - sorry

Damn, I finally figured out what the big problem was.

My A7V has an onboard ATA100 controller which I use for the RAID array, and for some reason unknown to me it fails to detect the new Mxtor drive with the correct size in 9 out of 10 restart, making Linux foobar.

My older Western Digital drive is just perfect on that control and has been for a long time.

So what's wrong, broken controller or faulty Maxtor drive. I tested my maxtor drive on the ATA66 controller because I didn't have the time to make the ATA100 control work on my spare 6gb Wndows test drive. And PowerMax returned no flaws.

Mighty strange

Ok... as a last effort I went and got new cables, an I sprung for two new ATA100 cables of the round sort.
(decided to mode the HDs to each their own controllers to get more speed.
And it seemed to solve to problem.

[root@Lovechild david]# hdparm -tT /dev/md0

/dev/md0:
Timing buffer-cache reads: 128 MB in 0.68 seconds =188.24 MB/sec
Timing buffered disk reads: 64 MB in 1.09 seconds = 58.72 MB/sec
[root@Lovechild david]# hdparm -tT /dev/md1

/dev/md1:
Timing buffer-cache reads: 128 MB in 0.75 seconds =170.67 MB/sec
Timing buffered disk reads: 64 MB in 1.04 seconds = 61.54 MB/sec
[root@Lovechild david]# hdparm -tT /dev/md2

/dev/md2:
Timing buffer-cache reads: 128 MB in 0.73 seconds =175.34 MB/sec
Timing buffered disk reads: 64 MB in 1.90 seconds = 33.68 MB/sec

YEAH !!
For the record:
md0 - / - ReiserFS, 10GB
md1 - /mnt/lfs/ - ReiserFS, 67GB
md2 - swap - 1GB <-- Overkill I know
hdc1 - /boot - ext2 - 50MB

[Stix]

Thanks for fixing my little snafu...It was late and I was'nt paying attention. /me bad..

Dude, you're getting some good transfer rates. A job well done. /me tips my hat.