[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Roadmap questions
> 3) Is there any documentation on the new VBD code? Is there yet a way > to make dynamically growing (sparse) disks or to be able to access a > domain's filesystem from domain 0? The current generation of VBD stuff is documented in docs/VBD-HOWTO.txt - there's some background about how VBDs and Virtual Disks are (currently) implemented, some info about the tools and a little walkthrough of an example task. The VBD / VD functionality is a bit like LVM and works in a similar way. The current state of play is this: * virtual disks are allocated from a pool of space set aside in one or more whole partitions or disks. They can't, for instance, just be files on some other domain's filesystem. * virtual disks can be created from that pool of free space as needed. Space reserved for a particular virtual disk is then allocated and hence unusable for other virtual disks, even if untouched by the domain it belongs to. This guarantees that space will be available if / when needed by the domain. As a result you can't speculatively "overbook" your virtual disk free pool. * You can enlarge existing virtual disks, export them to files, import from files and various other useful things (details in the readme / howto). * You can add and remove VBD access to / from domains dynamically, rather like hot plugging (e.g. to access a filesystem from dom0). Like Ian said, make sure you don't have filesystems writeable by more than one domain at once - most filesystems can't cope (and will get very badly corrupted). (actually, Linux also gets confused if someone else is writing a filesystem it has mounted read only but this shouldn't cause corruption). There's some sanity checking for shared disk mappings in the tools. Some of the VBD / VD stuff might change in the new I/O world. HTH. Mark ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/xen-devel
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