VRs Filesystem goes into Read-Only mode

[Vivek Kumar <vi...@indiqus.com>]

Hello Folks, 

I have a very interesting issue which occurs very frequently, I have CloudStack version 4.7 with XenServer 7.0 clusters. We are using NFS for primary storage, we have been observing that file system of virtual router goes to Read-Only mode very frequently. However other VMs running on the same SR doest have such issues but it happened specific for VR’s.  

I understand that Read-Only filesystem indicates that the filesystem is either not able to access to backend disk somehow or it looses the connectivity from backend SR but if my backend SR has issues then other VMs running on the same SR should also get affected. Has anyone came across with this issue ?  

So every-time  i need to reboot the VR in order to fix the file system which obviously leads some downtime. 

Regards
Vivek Kumar

Re: VRs Filesystem goes into Read-Only mode

[Andrija Panic <an...@gmail.com>]

Vivek,

different file systems will behave differently and the same goes for
different OSes.

In past, I've seen/had issue where the XFS (CentOS7 mostly) VMs would go
read-only during issues with storage, while the EXT4 (various Linux
variants) would NOT go read-only - during the intermittent issues (long
enough outages would bring those down as well)

Then also Linux in general will go read only FS, while Windows Server will
simply reboot itself (and possibly successfully boot if it was an
intermittent issue - thus resulting in auto-fix which is awesome IMO).

Different timeouts/FS behave differently - this is what I can tell for
sure. Fixing the underlying storage issue is a must.

Regards,
Andrija

On Mon, 27 Apr 2020 at 22:49, Vivek Kumar <vi...@indiqus.com> wrote:

> Hello Folks,
>
> I have a very interesting issue which occurs very frequently, I have
> CloudStack version 4.7 with XenServer 7.0 clusters. We are using NFS for
> primary storage, we have been observing that file system of virtual router
> goes to Read-Only mode very frequently. However other VMs running on the
> same SR doest have such issues but it happened specific for VR’s.
>
> I understand that Read-Only filesystem indicates that the filesystem is
> either not able to access to backend disk somehow or it looses the
> connectivity from backend SR but if my backend SR has issues then other VMs
> running on the same SR should also get affected. Has anyone came across
> with this issue ?
>
> So every-time  i need to reboot the VR in order to fix the file system
> which obviously leads some downtime.
>
> Regards
> Vivek Kumar
>
>

-- 

Andrija Panić