[dm-devel] Use device mapper to redirect to cache server?
malahal at us.ibm.com
malahal at us.ibm.com
Tue Jan 8 19:30:42 UTC 2008
Ph. Marek [philipp.marek at bmlv.gv.at] wrote:
> Hello everybody!
>
>
> I'd like to mirror write accesses to a block-device to two devices, get all
> all *read* accesses from one of these, and if it fails, to fallback to the
> other device.
This is exactly what 'mirror' target does (dm-raid1.c) without
read-balancing. But read on...
> The usage would be to use some kind of NAS box as persistent network block
> device, with some other machine with a lot of RAM as cache server; the cache
> server would get asked for data, and if it's not available, the request
> should go to the NAS directly.
I think, you are better of using the cache server as some kind of NFS
server as 'mirror' target's failure handling is heavy-weight.
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