[lustre-discuss] design to enable kernel updates

Brian Andrus toomuchit at gmail.com
Thu Feb 9 22:07:35 PST 2017


Do you mind if I inquire about the setup for your lustre systems?

I'm trying to understand how the MGS/MGT is setup for high availability.
I understand with OSTs and MDTs where all I really need is to have the 
failnode set when I do the mkfs.lustre
However, as I understand it, you have to use something like pacemaker 
and drbd to deal with the MGS/MGT. Is this how you approached it?

Brian Andrus

On 2/6/2017 12:58 PM, Vicker, Darby (JSC-EG311) wrote:
> Agreed.  We are just about to go into production on our next LFS with the
> setup described.  We had to get past a bug in the MGS failover for
> dual-homed servers but as of last week that is done and everything is
> working great (see "MGS failover problem" thread on this mailing list from
> this month and last).  We are in the process of syncing our existing LFS
> to this new one and I've failed over/rebooted/upgraded the new LFS servers
> many times now to make sure we can do this in practice when the new LFS goes
> into production.  Its working beautifully.
> Many thanks to the lustre developers for their continued efforts.  We have
> been using and have been fans of lustre for quite some time now and it
> just keeps getting better.
> -----Original Message-----
> From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of Ben Evans <bevans at cray.com>
> Date: Monday, February 6, 2017 at 2:22 PM
> To: Brian Andrus <toomuchit at gmail.com>, "lustre-discuss at lists.lustre.org" <lustre-discuss at lists.lustre.org>
> Subject: Re: [lustre-discuss] design to enable kernel updates
> It's certainly possible.  When I've done that sort of thing, you upgrade
> the OS on all the servers first, boot half of them (the A side) to the new
> image, all the targets will fail over to the B servers.  Once the A side
> is up, reboot the B half to the new OS.  Finally, do a failback to the
> "normal" running state.
> At least when I've done it, you'll want to do the failovers manually so
> the HA infrastructure doesn't surprise you for any reason.
> -Ben
> On 2/6/17, 2:54 PM, "lustre-discuss on behalf of Brian Andrus"
> <lustre-discuss-bounces at lists.lustre.org on behalf of toomuchit at gmail.com>
> wrote:
>> All,
>> I have been contemplating how lustre could be configured such that I
>> could update the kernel on each server without downtime.
>> It seems this is _almost_ possible when you have a san system so you
>> have failover for OSTs and MDTs. BUT the MGS/MGT seems to be the
>> problematic one, since rebooting that seems cause downtime that cannot
>> be avoided.
>> If you have a system where the disks are physically part of the OSS
>> hardware, you are out of luck. The hypothetical scenario I am using is
>> if someone had a VM that was a qcow image on a lustre mount (basically
>> an active, open file being read/written to continuously). How could
>> lustre be built to ensure anyone on the VM would not notice a kernel
>> upgrade to the underlying lustre servers.
>> Could such a setup be done? It seems that would be a better use case for
>> something like GPFS or Gluster, but being a die-hard lustre enthusiast,
>> I want to at least show it could be done.
>> Thanks in advance,
>> Brian Andrus
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