Gluster users - Sep 2012 - using KVM on glusterfs

hi, all:    I'm now working on constructing KVM servers based on glusterfs. 
    After many times searching on web, i found just a little information for
this task, so I had to
    write this email for seeking systematically instruction of how to make
glusterfs and KVM working together
    perfectly.


    And here are some questions I can not find any clearly answers:
    1. what are the relations between option cache=none(o_direct) in kvm and
direct-io-mode=[enable|disable] & option o-direct in translator
storage/posix, or something else?


    2. in previous mails it mentioned that raw image can be ran using cache=none
on glusterfs, but not mentioned what        options are used, such as
direct-io-mode, option o-direct in translator storage/posix, etc.
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1. is a deficiency of the libvirt test for safe filesystems. There is a 
way to override that, but I'm not sure off the top of my head what that 
was. You should be able to search the libvirt mailing lists for that 
error and find it though. I know I read it there a little while ago.
2. Should work with any current kernels and the "direct-io-mode=yes" 
mount option (using the fuse client).
3. That's correct. qemu-kvm sets o_direct for just about anything but 
type=raw,cache=none. That's (imho) a qemu bug. Any app that doesn't fall
back if it can't do O_DIRECT should.

Anyway, I hope that all helps.

On 09/24/2012 12:39 AM, flintcq wrote:
> 1. kvm can run on glusterfs using option cache=writeback, but can not 
> implement migration because of following error:
> Unable to migrate guset: Unsafe migration: Migration may lead to data 
> corruption if disks use cache != none
> 2. then i change the option as cache=none, but i doesn't work with 
> following error:
> could not open disk image ..... invalid argument
>
> 3.later, i found that fuse doesn't support cache=none(using O_DIRECT 
> flag), and if using disks with option type=raw, then cache=none may 
> workable, so i change the type of disks, but  still the same error 
> mentioned above.
>
> this is my most works.
>
>
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