Fajar Priyanto wrote:
On Thursday 09 March 2006 05:07 pm, Simone wrote:
Hi, once you remove sda, you need to setup grub on sdb to get it working. Just boot from the CentOS cd1 into linux rescue mode, and it should autodetect your system and mount it under /mnt/sysimage. Once you're in, chroot /mnt/sysimage /sbin/grub --> you get a prompt grub>
In my case I read in my grub.conf: title CentOS (2.6.9-22.0.2.106.unsupportedsmp) root (hd0,0)
so at the grub> prompt I would type
grub> root (hd0,0) grub> setup (hd0) grub> quit
You can then exit, reboot and your system should be up and running.
Hope this helps
Thanks Simone, It works now. Anyway, can you give me an insight how RAID-5 works in preventing the loss of data?
I'm testing it by copying a large file (20MB) into /root, and when I unplugged a drive, it seems that the data is still Ok. How does RAID-5 do this?
Thank you,
It uses parity information that it stores across all three drives. In your setup 1/3 of each drive is used for the parity information. Basically any two drives then have enough parity information to recreate the date on the third drive. With raid 5 the usable storage is C * (N -1) where C is the capacity of the drives and N is the number of them. So if you have 3 * 250GB disks the usable storage is 500GB. If two disks die at the same time kiss all your data good bye (although this is a pretty rare scenario)