At 22:09 25.01.99 +0100, you wrote:
>1) I downloaded the alpha version of the 0.90 raidtools
>and there are programs like raidhotadd and raidhotremove,
>but the included RAID5.HOWTO file does not cover these commands.
Yes, the howto is out of date with regard to the alpha code.
>The Howto says "if you connect a new drive" the kernel will
>reconstruct the lost data on this drive"
>but I think you must first partition the drive with fdisk
>with the same size as the other drives in the array.
>But is there a way to tell the kernel: "ok the new drive is ready,
>reconstruct all the data" ?
This depends. If the raid array isn't clean (power fail) on startup but the
component devices are available, the kernel will automatically
resynchronize the raid array. If a disk fails completely and has to be
replaced, as you say it must be partitioned and then added to the raid
array using
raidhotadd /dev/md<whatever> /dev/<new_partition>.
This command adds the new device to the array as a spare; if the array
contains failed components, the spare will be automagically synchronized to
the array.
>Does anyone of you know if there are a way to
>hot-add EIDE harddrives like the SCSI harddrives using
>the echo >/proc/scsi/...
Sorry, don't know.
>To support hot-reconstruction do you must set
>
>#define SUPPORT_RECONSTRUCTION 1 in linux/md.h ?
>(I think yes)
No changes necessary with the current raid/alpha patches.
>2) The RAID5.HOWTO says that you can autostart an md device at boot-time
>
>without having to mdadd all the devices.
>(this is archieved through changing the partition ID to 0xFD)
>
>Does allow this feature to boot of a RAID5 array giving to LILO
>/dev/md0 as root device , or is this autostart feature only available
>for non-root md devices ?
Yes, you can have root on an md device. The kernel will handle
initialisation of all raid devices before trying to mount anything.
However, you'll still need a small non-raid partition to hold your kernel
image and the stuff in /boot - while lilo can tell the kernel to use
/dev/md0 as root it can't read the kernel image or boot bessages off a raid
device.
Bye, Martin
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