A question about RAID 1

[Red10]

Ok, i want to use RAID 1... I am running Linux FC3, ASUS K8V SE mobo (AMD Athlon 64).
Question 1, if i use two SATA drives, could i use the onboard SATA RAID controller? would Linux detect and run Ok with this? or is there a better alternative?
Question 2, i understand RAID 1 mirrors the data, if one disk fails then the data is effectively mirrored on the other, if this happens, can i run the system on just the one disk? (i would not have thought this is possible, though) how do you go about rebuilding the array?

I've read about via google but some of the stuff is written by chimps or someone with too much brains to burn...

Anyone with got any helpful advice, yes i am a noob so be gentle...

[directhex]

unless you spend hundreds (i.e. you use your onboard), you'd use LVM, which is linux sofwtare raid.

a consequence of LVM and RAID 1 is you're not allowed two copies of /boot on 2 disks - the usual pattern is to have /boot on disk A, something else such as swap on disk B, and the remainder of the two disks can be RAIDed - if a disk dies, then you've lost /boot or swap, though, so it's not instantly recoverable (but you DO have a copy of all your other data) but recoverable by simply mounting on any PC, unlike the proprietary RAID solutions on windows.

[Red10]

unless you spend hundreds (i.e. you use your onboard), you'd use LVM, which is linux sofwtare raid.

a consequence of LVM and RAID 1 is you're not allowed two copies of /boot on 2 disks - the usual pattern is to have /boot on disk A, something else such as swap on disk B, and the remainder of the two disks can be RAIDed - if a disk dies, then you've lost /boot or swap, though, so it's not instantly recoverable (but you DO have a copy of all your other data) but recoverable by simply mounting on any PC, unlike the proprietary RAID solutions on windows.

This sounds like what i am after, how do you set this up? would FC3 have a system in place to parition or setup the array or do i need to use another system before hand then install?

Thanks for that concise reply by the way..

[directhex]

i expect the fc3 installer would set up LVM for you on request. i know the debian sarge installer does

[ikonia]

directhex,

I'm interested on the no two copies for /boot spread across the two disks.

I've got a number of hardware raided linux that allows this, but from what your saying you suggest this is a feature of LVM. I've not done much with LVM under linux, but I thought you could have 2 /boot partitions as long as you don't mark the second /boot partition as bootable ?

Also in lvm2 I believe this is possible to have the 2 /boot active partitions.

I'd certainly be interested in hearing more about this

[directhex]

i'm not too sure, i only have on ehard disk in my linux desktops, and the machines i have access to with raid1 use real hardware raid.

just what i read, last i was interested

things may have changed

[ikonia]

same here, most of my linux kit is respectable kit so I've had little experience of software raid under linux.

reading up though, I think the limitation is just having two active /boot partitions so that on the fly disk recovery can't take place for /boot.

however I believe you can have 2 /boot partitions under LVM1 but if /boot becomes corrupted the mirror'ed /boot will not take over, so a reboot from the second disk would be required but that would be in a working state.

I'll have a play with this for interests sake.