Re: [Xen-devel] Xen PVSCSI: status, issues and some tests

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, Feb 23, 2012 at 05:19:00PM -0700, jacek burghardt wrote:
>    I had just compiled pvscsi into 3.3.0-rc1 based on Konrad Rzeszutek Wilk
>    git. I had extracted patch from pvscssi-01 and applied it back to
>    3.3.0-rc1. I am able to load both xen-scsiback and xen-scsifront modules
>    but I don't see anything happening.
>    does xl supports pvscsi or it needs to be patched. I am running 4.2
>    unstable.

I don't think there is currently any PVSCSI support in xl/libxl.

-- Pasi

> 
>    On Tue, Feb 21, 2012 at 7:55 AM, Konrad Rzeszutek Wilk
>    <[1]konrad.wilk@xxxxxxxxxx> wrote:
> 
>      On Sun, Feb 19, 2012 at 03:22:08AM +0100, Thomas Weyergraf wrote:
>      > Hi, I am working as a system administrator at an internet platform
>      > service provider, and I am currently seeking to re-new our Xen
>      > virtualization infrastructure for which I am mostly responsible for.
>      > Currently, we run Xen 3.4.2/3.4.3 on RHEL/CentOS 5.x (5.7) as Dom0
>      > with CentOS 5.x pv-guests.
>      >
>      > Based on my experiments, I am currently looking into Xen 4.1.2 on
>      > RHEL/CentOS 6.x (6.2), with a vanilla 3.2 (3.2.0/3.2.6) kernel as
>      > Dom0 and stock RHEL/CentOS 6.x guests as HVM/pv-ops DomUs.
> 
>      Sweet.
>      >
>      > Our DomU's have their disk-devices on iscsi-storage backends (EMC,
>      > netapp, Linux IET), we attach the disks to Dom0 via open-iscsi
>      > initiator and pass them as 'phy'-type blockdevices, using
>      > blkfront/back.
> 
>      OK.
>      >
>      > As this is the time for a major overhaul anyway, I looked at
>      > 'pvscsi', which is very attractive to me for a bunch of
>      > (administrative) reasons. I have created a working pvscsi-setup with
>      > the following steps:
>      > 1. Use CentOS 6.2 as base system
>      > 2. Add Xen hypervisor from Michael Young's repository [1]. This is
>      > stock 4.1.2 with a patch from 4.1-testing pulled-in and various
>      > patches fixing compile-time issues, toolchain problems and system
>      > service management on RHEL-alike systems. (Nice work, btw!)
>      > 3. Use a vanilla 3.2.0 kernel from [2]kernel.org and a .config based
>      on
>      > a Fedora 16 stock-kernel config, tweaked to use pvscsi. As you know,
>      > Fedora 16 supports Dom0 operation and the only changes to the config
>      > are non-Xen related or add the Xen pvscsi config. I refrained from
>      > attaching the config to avoid mailinglist-clutter, but can do so on
>      > demand.
> 
>      Awesome.
>      > 4. I pulled and applied the pvscsi-patch found in this post [2] from
>      > Konrad Rzeszutek Wilk.
>      >
>      > Putting it all together yielded a "working setup" in which I am able
>      > to pass an Dom0-attached iscsi target to a DomU as a vscsi-device.
>      > In DomU context, I could partition the device, create a filesystem
>      > on it and copy/read/verify some 10gig of data to it. Very basic
>      > testing until now, essentially. However, the whole issue raised some
>      > questions:
>      >
>      > - I pvscsi actively maintained? Is someone working on this or even
>      > prepare it for upstream inclusion in the pv-ops framework of the 3.x
>      > series?
> 
>      So nobody has stepped up to do the upstream task and it is on my todo
>      list
>      but mostly at the end.
>      > - Has anybody started on adding the vscsi-semantics to the xl
>      toolstack?
> 
>      Not that I know of.
>      > - Using 'xm', I was only able to add a device via its SCSI tupel
>      > (HCTL, e.g: vscsi = [ '7:0:0:0, 0:0:0:1' ]) but not by any other
>      > device-node, such as '/dev/sde' or the
>      > '/dev/disk/by-path/<iscsi-iqn>' link. For these invocations, an
>      > "Error: Cannot find device <device>" message is given. I have not
>      > yet looked at the issue in detail (in
>      > /usr/lib64/python2.6/site-packages/xen/util/vscsi_util.py). Is this
>      > a known issue?
> 
>      First time I hear of it. But then I didn't even think to use /dev/sde
>      to pass in a device since SCSI devices aren't neccessarily block ones.
>      They can be scanners, medical devices, tape drivers, etc - which
>      might not have a /dev/sdX (thought they will have an /dev/sgX).
>      >
>      > Is there any developer(s) working on getting pvscsi ready for
>      > [3]kernel.org 3.x upstream inclusion? Should i better retool my
>      efforts
>      > using pv-ops xen/stable 2.6.32 series?
> 
>      For 3.x upstream inclusion - not that I know off.
>      Why would you want to retool your effort in using the 2.6.32 series
>      as opposed to 3.x? What other items is the 3.x missing compared to
>      2.6.32?
> 
>      Now the good news is that I am happy to keep this going (pv-scsi)
>      and fixing it, and having incremental updates to make it better.
>      >
>      > If applicable, I'd be more than happy to provide assistance to move
>      > forward pvscsi. Maybe, as a start, provide a short, practical howto
>      > about what I did above to get pvscsi working and reference it by the
>      > Xen PVSCSI wiki page [3]?
> 
>      Sure. Also, did you use the git tree to pull the patches or just
>      the big patch file ? The git tree has fixes to make it work under 3.2 as
>      well.
>      >
>      > Regards,
>      > Thomas Weyergraf
>      >
>      > [1] [4]http://xenbits.xen.org/people/mayoung/EL6.xen/
>      > [2]
>      [5]http://lists.xen.org/archives/html/xen-devel/2011-11/msg02268.html
>      > [3] [6]http://wiki.xen.org/xenwiki/XenPVSCSI
>      >
>      >
>      >
>      > _______________________________________________
>      > Xen-devel mailing list
>      > [7]Xen-devel@xxxxxxxxxxxxx
>      > [8]http://lists.xen.org/xen-devel
> 
>      _______________________________________________
>      Xen-devel mailing list
>      [9]Xen-devel@xxxxxxxxxxxxx
>      [10]http://lists.xen.org/xen-devel
> 
> References
> 
>    Visible links
>    1. mailto:konrad.wilk@xxxxxxxxxx
>    2. http://kernel.org/
>    3. http://kernel.org/
>    4. http://xenbits.xen.org/people/mayoung/EL6.xen/
>    5. http://lists.xen.org/archives/html/xen-devel/2011-11/msg02268.html
>    6. http://wiki.xen.org/xenwiki/XenPVSCSI
>    7. mailto:Xen-devel@xxxxxxxxxxxxx
>    8. http://lists.xen.org/xen-devel
>    9. mailto:Xen-devel@xxxxxxxxxxxxx
>   10. http://lists.xen.org/xen-devel

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel