[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] VBD extents



> So in XEN 2.0 is VBD grow/shrink used?

Yes, Xend uses them when creating a VBD.  Xend first creates a given VBD, 
which starts off with zero size.  Xend then adds exactly one segment to the 
VBD using a grow message - this segment describes the device the VBD is 
mapping.

Shrink messages probably aren't used anywhere at all.

> 0).  If indeed these messages will eventually be removed, i take it XEND
> will need to send a message to blkback identifying the disk device driver

That sounds right - basically just removing the vestiges of multi-extent 
support in blkback so that each VBD has exactly one extent.

Cheers
Mark

> Eric
>
> Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx> wrote:
> > Can anyone tell me what exactly the VBD extents are used for
> > in the XEN back-end block device driver? It almost looks
> > like each virtual disk is made up of multiple physical drives
> > if I read the code correctly (for each VBD grow message
> > received by blkback, it opens a device and retreives various
> > info such as its size).
>
> The extent stuff is left over from Xen 1.2, where we effectively had to
> do our own version of LVM inside Xen. We'd like to give the code a
> spring clean and do away with the grow/srink control messages
> altogether. At the same time it would be sensible to add support for
> multiple blk rings, and possibly the ability to 'tunnel' certain ioctls
> e.g. eject CD.
>
> Ian
>
>
> -------------------------------------------------------
> The SF.Net email is sponsored by: Beat the post-holiday blues
> Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek.
> It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.sourceforge.net/lists/listinfo/xen-devel
>
>
> ---------------------------------
> Do you Yahoo!?
>  Yahoo! Mail - 250MB free storage. Do more. Manage less.


-------------------------------------------------------
This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting
Tool for open source databases. Create drag-&-drop reports. Save time
by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc.
Download a FREE copy at http://www.intelliview.com/go/osdn_nl
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.