Bug#678693: Please add a /usr/share/initramfs-tools/scripts/local-block/ script

Goswin von Brederlow goswin-v-b at web.de
Mon Jun 25 13:20:50 UTC 2012

Ritesh Raj Sarraf <rrs at researchut.com> writes:

> Do you see this affecting multipath?
> There is no use case to run dm-multipath on a local block device.

Don't be too sure about that. I've been playing with dm-multipath on
local block devices because it has a timeout feature. If a single device
in a raid hangs (which can take up to several minutes till all the
resets on all levels have been tried before you get an error or may
actualy hang forever) you can use multipath to make it give up faster.

> There are setups where you would want LVM on top of your SAN Multipath
> Device, but I think we already take care of that.

Since multipath-tools doesn't provide any initramfs-tools scripts yet
I don't see how that could be. I think booting from a multipath device
isn't supported at all yet, right?

I can also imagine setups with a multipath SAN with LVM that and each LV
having a different multipath setup. E.g. LV1 uses path1 with fallback to
path2 and LV2 the other way around.

> Please let me know if you are expecting something else from multipath.

One of the problems in current initramfs-tools is with devices that take
a long time to be detected. My experience with external enclosures was
that detecting the drives takes rather long, just like USB takes it

So I think that if you add support to boot from multipath then it would
definetly fall under the problem cases and need a local-block script
rather than local-top.


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