Re: [Xen-devel] [4 Patches] New blktap implementation, 2nd try

[Gerd Hoffmann <kraxel@xxxxxxxxxx>]

Kevin Wolf wrote:
>>    Having isolated tapdisks, and presenting the associated images as
>> Linux block devices means that (a) you can use tools like ionice to
>> prioritize individual block devices rather than having to set priority
>> for *all* of qemu, (b) individual tapdisks can serve block devices for
>> multiple VMs -- this is useful if you want to implement a cache for
>> many VMs booting from a common image, it's also good for complicated
>> distributed block devices like Parallax (which Dutch can tell you more
>> about if you are interested) -- again, this is a case where having the
>> code in qemu is bad, you want multiple VMs to share the tapdisk-based
>> implementation.  Finally, (c) tapdisk can be used to directly loopback
>> the image into linux, which allows people to more easily work with the
>> image's contents.  Again, here I don't think you want a whole qemu.

upstream qemu recently got qemu-nbd, which can do the very same thing
using the linux nbd driver.

cheers,
  Gerd


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