Re: [Xen-users] Database crashes when using Xen PVH

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Jun 21, 2016 at 02:21:58PM +0200, Tomas Mozes wrote:
> On Tue, Jun 21, 2016 at 12:33 PM, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> 
> > On Mon, Jun 20, 2016 at 03:10:02PM +0200, Tomas Mozes wrote:
> > > We observed several crashes on MariaDB databases when using Xen PVH mode.
> > > After switching back to Xen PV, all fine. The strange thing is that on
> > > application servers it works just fine (speeded up compilation times by
> > > 30%).
> > >
> > > Gentoo Linux with kernel 4.1, Xen 4.6.0/4.6.1.
> > >
> > > More details reported on Gentoo / MariaDB bug trackers:
> > > https://bugs.gentoo.org/show_bug.cgi?id=584828
> > > https://jira.mariadb.org/browse/MDEV-10167
> > >
> >
> > First thing first, I'm not sure which version of PVH you're using (I
> > suppose you're using PVHv1 / original PVH due to the kernel version. I
> > know it is quite confusing...), but please note whatever version that is
> > out there is *NOT* considered production ready. Please do not put your
> > precious data there.
> >
> > It is hard to tell what went wrong because PVH code path in hypervisor
> > and Linux kernel is very different from PV code path -- that's why it is
> > considered a new mode.
> >
> > I've CC'ed Roger who is currently working on PVH (new version...). But
> > he's on vacation right now so you will need to wait a bit for him to
> > come back online.
> >
> > Wei.
> >
> > > Best regards,
> > > Tomas Mozes
> >
> > > _______________________________________________
> > > Xen-users mailing list
> > > Xen-users@xxxxxxxxxxxxx
> > > http://lists.xen.org/xen-users
> >
> >
> Hello,
> sorry I cannot figure out which PVH version I use - how to check for it?
> 

I don't remember a way off the top of my head, sorry.

> On the Xen page (http://wiki.xen.org/wiki/Xen_Project_Software_Overview) I
> found that "PVH is considered experimental in 4.4 and 4.5". So I thought
> that in 4.6 it's something stable as I wasn't able to find any more
> information (except for
> https://blog.xenproject.org/2014/01/31/linux-3-14-and-pvh/). I thought like
> 4.1 moved greatly from 3.14 and it's production ready.
> 

The wording is that "but additional tuning is needed (probably in the
4.6 release) before it should be used in production" which implies it is
not yet production ready.

> Maybe it would be good to add some more information that it's still
> "experimental" or "unstable".
> 

Yes, there is a page for that:

http://wiki.xen.org/wiki/Xen_Release_Features

PVH is listed as "preview".

Wei.

> Best regards,
> Tomas Mozes

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