[lustre-discuss] design to enable kernel updates

Vicker, Darby (JSC-EG311) darby.vicker-1 at nasa.gov
Fri Feb 10 21:03:24 PST 2017

Sure.  Our hardware is very similar to this:


We are using twin servers instead two single chassis servers as shown there but functionally this is the same – we can just fit more stuff into a single rack with the twin servers.  We are using a single JBOB per twin server as shown in one of the configurations on the above page and are using ZFS as the backend.  All servers are dual-homed on both Ethernet and IB.  A combined MGS/MDS is at address for IB and X.X.98.30 for Ethernet. The secondary MDS/MGS on the .31 address for both networks.  With the combined MDS/MGS, they both fail over together.  This did require a patch from LU-8397 to get the MGS failover to work properly so we are using 2.9.0 with the LU-8397 patch and are compiling our own server rpms.  But this is pretty simple with ZFS since you don't need a patched kernel.  The lustre formatting and configuration bits are below.  I'm leaving out the ZFS pool creation but I think you get the idea.  

I hope that helps. 


if [[ $HOSTNAME == *mds* ]] ; then

    mkfs.lustre \
        --fsname=hpfs-fsl \
        --backfstype=zfs \
        --reformat \
        --verbose \
        --mgs --mdt --index=0 \
        --servicenode=${LUSTRE_LOCAL_TCP_IP}@tcp0,${LUSTRE_LOCAL_IB_IP}@o2ib0 \
        --servicenode=${LUSTRE_PEER_TCP_IP}@tcp0,${LUSTRE_PEER_IB_IP}@o2ib0 \

elif [[ $HOSTNAME == *oss* ]] ; then

   num=`hostname --short | sed 's/hpfs-fsl-//' | sed 's/oss//'`
   num=`printf '%g' $num`

   mkfs.lustre \
       --mgsnode=X.X.98.30 at tcp0, at o2ib0 \
       --mgsnode=X.X.98.31 at tcp0, at o2ib0 \
       --fsname=hpfs-fsl \
       --backfstype=zfs \
       --reformat \
       --verbose \
       --ost --index=$num \
       --servicenode=${LUSTRE_LOCAL_TCP_IP}@tcp0,${LUSTRE_LOCAL_IB_IP}@o2ib0 \
       --servicenode=${LUSTRE_PEER_TCP_IP}@tcp0,${LUSTRE_PEER_IB_IP}@o2ib0 \


#local  foreign/-  label       [md|zfs:]device-path   [journal-path]/- [raidtab]

hpfs-fsl-mds0  hpfs-fsl-mds1  hpfs-fsl-MDT0000  zfs:metadata/meta-fsl

hpfs-fsl-oss00 hpfs-fsl-oss01 hpfs-fsl-OST0000  zfs:oss00-0/ost-fsl
hpfs-fsl-oss01 hpfs-fsl-oss00 hpfs-fsl-OST0001  zfs:oss01-0/ost-fsl
hpfs-fsl-oss02 hpfs-fsl-oss03 hpfs-fsl-OST0002  zfs:oss02-0/ost-fsl
hpfs-fsl-oss03 hpfs-fsl-oss02 hpfs-fsl-OST0003  zfs:oss03-0/ost-fsl
hpfs-fsl-oss04 hpfs-fsl-oss05 hpfs-fsl-OST0004  zfs:oss04-0/ost-fsl
hpfs-fsl-oss05 hpfs-fsl-oss04 hpfs-fsl-OST0005  zfs:oss05-0/ost-fsl
hpfs-fsl-oss06 hpfs-fsl-oss07 hpfs-fsl-OST0006  zfs:oss06-0/ost-fsl
hpfs-fsl-oss07 hpfs-fsl-oss06 hpfs-fsl-OST0007  zfs:oss07-0/ost-fsl
hpfs-fsl-oss08 hpfs-fsl-oss09 hpfs-fsl-OST0008  zfs:oss08-0/ost-fsl
hpfs-fsl-oss09 hpfs-fsl-oss08 hpfs-fsl-OST0009  zfs:oss09-0/ost-fsl
hpfs-fsl-oss10 hpfs-fsl-oss11 hpfs-fsl-OST000a  zfs:oss10-0/ost-fsl
hpfs-fsl-oss11 hpfs-fsl-oss10 hpfs-fsl-OST000b  zfs:oss11-0/ost-fsl


options lnet networks=tcp0(enp4s0),o2ib0(ib1)
options ko2iblnd map_on_demand=32

-----Original Message-----
From: Brian Andrus <toomuchit at gmail.com>
Date: Friday, February 10, 2017 at 12:07 AM
To: Darby Vicker <darby.vicker-1 at nasa.gov>, Ben Evans <bevans at cray.com>, "lustre-discuss at lists.lustre.org" <lustre-discuss at lists.lustre.org>
Subject: Re: [lustre-discuss] design to enable kernel updates


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
>> _______________________________________________
>> lustre-discuss mailing list
>> lustre-discuss at lists.lustre.org
>> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
> _______________________________________________
> lustre-discuss mailing list
> lustre-discuss at lists.lustre.org
> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org

More information about the lustre-discuss mailing list