[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC] support more qdisk types
Konrad Rzeszutek Wilk wrote: > On Wed, Jan 27, 2016 at 07:42:49PM -0700, Jim Fehlig wrote: >> On 01/27/2016 02:09 PM, Konrad Rzeszutek Wilk wrote: >>> On Wed, Jan 27, 2016 at 02:25:51PM -0600, Doug Goldstein wrote: >>>> On 1/27/16 12:32 PM, Konrad Rzeszutek Wilk wrote: >>>>> On Mon, Jan 25, 2016 at 05:25:02PM -0700, Jim Fehlig wrote: >>>>>> I would like to hear the community's opinion on supporting more qdisk >>>>>> types in >>>>>> xl/libxl, e.g. nbd, rbd, iSCSI, etc. I prefer supporting additional >>>>>> qdisk types >>>>>> in libxl over apps like xl or libvirt doing all the setup, producing a >>>>>> block >>>>>> device, and then passing that to libxl. Each libxl app would have to >>>>>> re-implement functionality already provided by qdisk. libxl already >>>>>> supports >>>>>> IDE, AHCI, SCSI, and Xen PV qdisks. My suggestion is to extend that to >>>>>> initially >>>>>> include nbd, rbd, and iSCSI. Sheepdog, ssh, etc. could be added in the >>>>>> future. >>>>> ssh? >>>>>> I considered several approaches to supporting additional qdisk types, >>>>>> based >>>>>> primarily on changes to the disk cfg and interface. At one extreme is to >>>>>> change >>>>>> nothing and use the existing 'target=' to encode all required config for >>>>>> the >>>>>> additional qdisk types. libxl would need to be taught how to turn the >>>>>> blob into >>>>>> an appropriate qdisk. At the other extreme is extending >>>>>> xl-disk-configuration >>>>> Either way - new backends would require changes in both libxl and libvirt >>>>> right? >>>>> The libxl would need to understand the new 'target=' blob to parse it out? >>>>> >>>> libvirt would probably just do what its doing now. Since it can setup >>>> the connection and pass the file descriptor into libxl. Honestly I don't >>>> see the advantage here because libvirt does a better job from a security >>>> standpoint and unless the goal is to have everything and the kitchen >>>> sink in libxl/xl. There's already a number of ways to skin the cat (xl, >>>> libvirt, xapi, openstack), why another one? >>> I believe what Jim is saying that there needs to be some parsing in libxl >>> so that it can pass the right information to QEMU. >> Correct. The info is also needed when libxl creates the device in xenstore. > > I think that would be awesome - especially with the iSCSI and Sheepdog. > > The one thing that I am worried about is bitrotting. And I would think > if test-cases were added for this support - while it is bigger upfront > cost - would benefit us long term. Agreed. At a minimum I planned to add testing of any new disk config settings to tools/libxl/check-xl-disk-parse. Were you thinking of something more end-to-end like a new OSSTEST case? Regards, Jim _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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