On Thu, Apr 01, 2004 at 09:56:40AM +0400, Brad Campbell wrote:
Jeff Garzik wrote:
it out and insert the new drive in the array. The array starts rebuilding - no effect on the uptime and only a slight loss in throughput. Plus it's seamless.
Yeah, md+mdadm can do all this right now, provided the hardware and driver support is there...
Yes, my point however is for low budget stuff with software raid the driver support is not yet there in a vanilla kernel.
I can't just whack a sata drive off one of my promise SATA150-TX4 controllers, pop another one in and have the kernel rescan the partition table and realise a new drive was present. (YET!)
I'm sort of confused... which are the combinations that allow me to hotswap a
disk w/ software raid. I don't mind doing some mdadm operations, I'm just
interested in how I can avoid rebooting.
I thought I couldn't, now I learn you can "provided the hardware and driver support is there"... can you detail a little more?
AFAICS, the steps should be:
1) (optional) be nice, and tell md you are about to yank a drive using hot-remove
2) (required on ICH5, optional on others) be nice, and tell SATA you are about to yank a drive (not implemented yet in libata)
3) unplug the SATA cable
4) swap out drives
5) plug in the SATA cable (kernel automatically notices the new device; not implemented yet in libata)
6) new device is probed by kernel SATA driver
7) kernel executes /sbin/hotplug (normal for any hotplug event)
8a) /sbin/hotplug magic issues the md ioctls to hot-add a new device. This requires some knowledge in code, or in a config file, of how to associate a new device on a random controller with a specific array.
or
8b) sysadmin uses mdadm to hot-add the new device, to the specified array.
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