Re: [Engine-devel] Proposal for support ISO domain on other types of file based storage.

On 03/18/2013 04:43 PM, Ayal Baron wrote: ----- Original Message ----- Mark Wu : On Sun 17 Mar 2013 10:12:55 PM CST, Ayal Baron wrote: ----- Original Message ----- Hi guys, Currently, ISO domain is only supported on NFS storage. It could improve the ease of use if it allows other types of file based storage to store ISO images. After an investigation, I found there's not any restriction on this idea. So the whole work is removing the limitation on engine side. That means engine should allow ISO domain could have different storage type from the data center it's attached, like what we do with nfs ISO domain in SAN DC. I start this idea with localfs. I know local storage can't be seen in cluster level. But it also provides a choice if no NFS available. VMs can be created on the host which has the ISO repo, and then be migrated to any other host in the cluster. I have done the initial patches: allow creation ISO domain on localfs [1] and support import ISO domain on localfs [2] I don't have much experience in java/j2ee/web development and engine architecture. The patches just work for me. I am not sure if it will bring some potential problems. So any feedback on the patch or the idea will be appreciated very much. Haven't looked at the patches yet, but wrt the idea, I agree on the need (being able to attach ISOs from anywhere and not just nfs) but I think the way to do this should be by getting rid of the ISO domain type altogether. I think ISO domain on localfs is useful for a simple setup or demo, such as oVirt all-in-one. Basically what we need is: 1. a way to connect to file based storage (let's leave block aside for now) - this already exists via the connectStorageServer verb 2. a way to list and present a file system tree in gui (give an arbitrary path to vdsm and list content) and possibly filter results by type (vfd, iso) - does not exist today. Possibly some security aspects here that need hashing out. 3. a way to specify a path to a file when attaching an iso/vfd to a VM - this is the way it works today This would devoid the need for isoUploader and allow users to simply manage an nfs export with files. Next step would be to make connectStorageServer support httpfs [1] and then we'd be able to mount ISOs directly over http (hopefully this would be sufficient to support ISOs stored on S3, swift, glance, etc). Actually, we could use the qemu curl backend image support directly. That means we don't need mount the place storing ISO images. We can just maintain a list of ISO image with its link, which could be http, ftp and ssh. That will be fine to start a VM on a existing extern ISO image. I also would like to maintain a ISO image cache on the local host to avoid to re-streaming the ISO image from the ISO image repositories every time. That will be helpful for people who is suffered from the network bottleneck. We have a similar requirement for glance support (not limited to ISOs, rather to all read-only images) so that should be tackled with a broader solution. In that case, I suppose qemu's copy-on-read + httpfs (you mentioned above) could help. It can avoid accessing the same backing file sectors repeatedly. But the copied content can't be shared by multiple VM using the same backend image.

[1] http://httpfs.sourceforge.net/ Mark. [1] http://gerrit.ovirt.org/#/c/12687/ [2] http://gerrit.ovirt.org/#/c/12916/ _______________________________________________ Engine-devel mailing list Engine-devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel _______________________________________________ Engine-devel mailing list Engine-devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel -- --- 舒明 Shu Ming Open Virtualization Engineerning; CSTL, IBM Corp. Tel: 86-10-82451626 Tieline: 9051626 E-mail: shuming(a)cn.ibm.com or shuming(a)linux.vnet.ibm.com Address: 3/F Ring Building, ZhongGuanCun Software Park, Haidian District, Beijing 100193, PRC