Re: [Xen-users] [Xen-Users] Issues with root NFS on Dom0

[Adam Goryachev <mailinglists@xxxxxxxxxxxxxxxxxxxxxx>]

Hi Brandon,

I tried a NFS root solution for my group of dom0 hosts a number of years 
ago (using xen4.0). Due to a number of lockups and issues I suffered 
over a period of time my "solution" which has worked very well for me, 
using a custom initrd I actually copy the rootfs to a ram disk, and then 
boot from memory. This meant that I no longer had to worry about the NFS 
server availability for the dom0's to be working, and also I could use a 
single copy of the rootfs for all dom0's, and no problem with a shared 
/tmp or /etc and so on.
While I can still see the advantages of using this style solution (NFS 
root), I think there are better options today (that I haven't 
investigated/used). One issue with the shared NFS root was also dealing 
with updates/upgrades, where my current solution handles that (chroot, 
install new package, reboot dom0 one at a time with appropriate live 
migrations).
Today, with all the fancy management tools like puppet/chef/etc (I know 
nothing about them, except I vaguely understand they should support 
booting and installing/configuring your dom0, including any 
update/upgrades on each reboot). You might want to look into some of 
those options.
Of course, none of that directly helps you with your issue.

Have you tried getting shell access early in the init process, and 
measuring/testing what is actually wrong, is it CPU performance, network 
performance, or NFS performance? Possibly there is a network card driver 
issue, have you tried a different network card (different 
brand/model/etc)? What about your switch, does it report any collisions, 
dropped packets, errors, etc? Faulty network cable perhaps?
Sorry I couldn't help really, but maybe it will provide some ideas.

Regards,
Adam

On 21/07/15 09:24, Brandon Perez wrote:
> Hello All,
>
>     Here's a quick overview of my setup:
>     - Hardware: TI DRA72 Chip, Arm Cortex A15
>     - Xen:
>         - Version: 4.6-unstable
>         - Compiled from source, with some local changes
>         - Branch: master
>         - Commit: ecdae1cfaa7f6123decaa1b9d7205c3ff726b941
>         - Repo URL: git://xenbits.xen.org/xen.git
>     - Linux Kernel:
>         - Version: 3.14
>         - Compiled From source, with some local changes
>         - Branch: android-3.14-6AL.1.0
>         - Commit: 7b2f1133857414b96927c06f08ed6c440f5472e7
>         - Repo URL: git://git.omapzoom.org/kernel/omap.git
>
>     I'm attempting to get an root NFS boot working with a Linux Dom0. 
> The boot works, but is horrendously slow. A /bin/sh boot takes several 
> minutes, and an init boot takes hours (I gave up on init after 20 
> minutes). For comparison, a boot from an SD card takes about 15 seconds.
> Also, with a native Linux root NFS boot, the total boot time is about 
> 25 seconds, so the issue seems to be related with Xen or my Xen 
> configuration.
>     I haven't done a lot of debugging yet, so I don't have much 
> additional information. Before I go deep into debugging this, I was 
> wondering if this is an issue you guys have heard of before. Also, I 
> was wondering if there was any immediate things you can think of that 
> might be causing this problem.
>     One thing I have quickly looked over is /proc/interrupts. For a 
> native boot, there are several hundred ethernet transmit interrupts. 
> On the Xen boot, there are several million transmit interrupts.
> Thanks,
>
>     Brandon Perez
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxx
> http://lists.xen.org/xen-users

--
Adam Goryachev Website Managers www.websitemanagers.com.au

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