On Thu, Oct 12, 2006 at 04:35:02PM +0200, Jean-Luc Coulon (f5ibh) wrote: > *Real* hardware raid doesnt need an OS layer / driver to work. > This kind of raid relies on the BIOS *and* on a Windows driver. > It is more a raid feature enabled in the BIOS and managed by the > Windows driver. > Linux can or not support this BIOS feature depending of the chipset. > > Most of the time, you have to disable the raid in the BIOS and use pure > software raid. > > In case if a raid1, if a disk fails you get a message from the system. > If you have spare disks (configured and installed as so in the raid), > the raid is rebuilt on the spare disk. You will notice disk activity > related to this mirroring. Then you can wait until you can shutdown > your system and remove/replace the defective disk. Then restart the > system and use mdadm to reinstall the disk in the array. > If you have no spare, the raid is degraded and you are running on the > safe disk without any redundancy. > You have, the same way as before, to shutdown your system and remove / > replace the defective disk. > > In case of a raid0, you have no redundancy and the filesystem relying > on this raid will die. > > Remarks : > - SATA is told to be hotplug but most of the motherboards dont support > hotplugging of disks on their SATA controller. This is why you have to > shutdown your system.
Actually most SATA controllers DO support hotplug. The linux kernel doesn't support SATA hot plug yet (although supposedly that is being worked on). > - There are disk failures and there are controller failures. If both > your disk are on the same controller, your system will crash. If your controller fails, most likely the system will crash when the driver gets very unexpected results. This is a rather unusual case, and very expensive to protect against. Disk failures are much more common and fortunately much easier to protect against. > - The swap has to be on the raid also (or on a logical volume of LVM > which is built over the raid) otherwise, you will probably crash your > system at the failure. That is for sure. > You can download and install mdadm : the doc files in > /usr/share/doc/mdadm contain valuable informations. > > It is often easier to repair have access to ext3 (which is > ext2+journal) from a system you have booted from a live CD, just in > case of a weird problem on the filesystem. Also grub only supports some filesystems for /boot, so it makes sense to keep / as something supported and simple. After all if your / is small and doesn't change much why would you need any fancy filesystem for it? -- Len Sorensen -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
