On 09/08/2015 08:40 PM, Deepak Shetty wrote:
On Tue, Sep 8, 2015 at 8:32 PM, Daniel P. Berrange
<berra...@redhat.com <mailto:berra...@redhat.com>>wrote:
On Tue, Sep 08, 2015 at 06:34:09PM +0530, Prasanna Kumar Kalever
wrote:
> This patch adds a way to specify multiple backup volfile servers
to the gluster
> block backend of QEMU with both tcp and rdma transport types.
>
> Problem:
>
> Currenly VM Image on gluster volume is specified like this:
>
> file=gluster[+tcp]://server1:24007/testvol/a.img
>
> Assuming we have have three servers in trustred pool with
replica 3 volume
> in action and unfortunately server1 (mentioned in the command
above) went down
> for some reason, since the volume is replica 3 we now have other
2 servers
> active from which we can boot the VM.
>
> But currently there is no mechanism to pass the other 2 gluster
server
> addresses to qemu.
>
> Solution:
>
> New way of specifying VM Image on gluster volume with backup
volfile servers:
>
> file=gluster[+transport-type]://server1:24007/testvol/a.img\
> ?backup-volfile-servers=server2&backup-volfile-servers=server3
Comparison with RBD syntax:
file=rbd:pool/image:auth_supported=none:\
mon_host=mon1.example.org
<http://mon1.example.org>\:6321\;mon2.example.org
<http://mon2.example.org>\:6322\;\
mon3.example.org <http://mon3.example.org>\:6322,if=virtio,format=raw
As Peter already mentioned, you're missing port numbers.
It is slightly unpleasant to have different ways of specifying the
first
vs second, third, etc hosts. I wonder if it would be nicer to keep all
the hostnames in the host part of the URI. eg
file=gluster[+transport-type]://server1:24007,server2:3553,server3:2423/testvol/a.img\
?backup-volfile-servers=server2&backup-volfile-servers=server3
Of course it ceases to be a wellformed URI at that point, so
another option
would be to just allow the host part of the URI to be optional,
and then
accept mutliple instances ofa 'server' arg, eg
file=gluster[+transport-type]:///testvol/a.img\
?server=server1:2424&server=server2:2423&sever=server3:34222
Is it allowed to have this syntax and be a valid URI ? I admit i
haven't looked at the
URI rfc for a long time now, hence the Q. Also looking at rbd syntax,
it looks
to follow this model already is it ? Whats the difference between
using ':' to
separate key=value pairs Vs using '?" query syntax ? Should we look at
having
a uniform way of specifying URI be it rbd or gluster or sheepdog ... ?
If yes
what that uniform syntax be using ':" or '?" ?
Answering myself, based on what I figured .... :)
Looks like rbd syntax is a propertiary one and not adhering to URI rfc,
while gluster syntax
is URI compliant so the 2nd option suggested by danpb seems good
Also need to ensure that old syntax of providing server:port in the
authority field should
be honoured so that older clients/apps generating the old syntax won't
be broken
thanx,
deepak
