Something that is not clear to me, which I''ve not found any information on is, is it possible for guests to ''share'' a card that''s installed in the host. More specifically, in a GFS cluster for example, the storage can be in various forms but what if it''s FC based? Can guests share a fibre channel HBA? Even if they did, one would have to use a different fencing method than the FC switch of course but could it be done and what might the complications be? Mike _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Mon, Jan 26, 2009 at 6:31 AM, lists@grounded.net <lists@grounded.net> wrote:> Something that is not clear to me, which I''ve not found any information on is, is it possible for guests to ''share'' a card that''s installed in the host.Long answer : Yes, but chances are you might not have the necessary requirements yet. http://blog.fosketts.net/tag/pvscsi/ http://en.wikipedia.org/wiki/NPIV _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Nick mentioned that the host can share it''s drives/storage so this has made me wonder about something. In my testing so far, each guest usually has NFS mounts to a central storage. I don''t know the NFS protocol well so am only guessing that such a connection means chatter on the network. So, if there are say 10 guests on a server, each connected to the shared storage via NFS, this would end up being a ton more Ethernet chatter than it would if I could simply connect the storage ONCE to the host, then give each guess access to this. Make sense? Mike On Mon, 26 Jan 2009 08:21:00 +0700, Fajar A. Nugraha wrote:> On Mon, Jan 26, 2009 at 6:31 AM, lists@grounded.net <lists@grounded.net> > wrote: > >> Something that is not clear to me, which I''ve not found any information >> on is, is it possible for guests to ''share'' a card that''s installed in >> the host. >> > Long answer : Yes, but chances are you might not have the necessary > requirements yet. > > http://blog.fosketts.net/tag/pvscsi/ > http://en.wikipedia.org/wiki/NPIV_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Mon, Jan 26, 2009 at 11:35 AM, lists@grounded.net <lists@grounded.net> wrote:> Nick mentioned that the host can share it''s drives/storage so this has made me wonder about something.I think we''re talking about two different things here. I was talking about how a guest can share hosts'' HBA so each guest would think they have their own "dedicated" HBA. This is needed for some situations, for example tape backups. Sharing a drive/storage (as in block device, not the fs) should simply be mapping host''s storage using the usual phy:/ vbd, and (optionally, if multiple guests access the same storage) some kind of clustered fs. Note that there are also methods like using tap:qcow to have multiple guests share reads to the host''s block device while writes are redirected to a different file. Sharing host fs is done using the old NFS/CIFS method.> > In my testing so far, each guest usually has NFS mounts to a central storage. I don''t know the NFS protocol well so am only guessing that such a connection means chatter on the network.Yes.> > So, if there are say 10 guests on a server, each connected to the shared storage via NFS, this would end up being a ton more Ethernet chatter than it would if I could simply connect the storage ONCE to the host, then give each guess access to this.I get your point, but AFAIK it would not reduce network traffic as NFS makes very little use (if any) of cache, so that all traffic would end up in the NFS server anyway, which is why on the other thread I mentioned you should have a dedicated storage network. You might have better luck with cachefs to reduce NFS network traffic. Regards, Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users