On 20/01/2013 5:08 AM, Roy Sigurd Karlsbakk wrote:
Hi all
As far as I can understand from the bcache docs, a volume cached with bcache,
must be formatted and setup for bcache in the first place. I come from a ZFS
environment, where adding SLOG or L2ARC is done dynamically, so I have a few
questions:
- Would it be somewhat possible to add caching to an existing volume and its
data?
- What would happen if the cache device dies - does the whole filesystem become
inaccessible?
I've actually been wondering a bit about this - its not exactly clear in
the docs as to what I should do to set up bcache.
In my case, I have a RAID6 over 4 x 2Tb drives. It lives as /dev/md2.
/dev/md[01] are RAID1 on a pair of 80Gb drives for boot and LVM.
As the system is a Xen Dom0, all the DomU (guests) run from their own LV
on the RAID6. So - it would make sense to add bcache to /dev/md2.
I'm a bit confused from reading the docs if I can attach to the existing
/dev/md2 or I have to create something from scratch. Obviously,
attaching to an existing RAID device is going to be the preferred method.
Covering this in the docs or even on the web site would probably be
beneficial for a lot of people - especially as I feel that this is
getting closer to be merged with the upstream kernel.
--
Steven Haigh
Email: [email protected]
Web: https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
Fax: (03) 8338 0299
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