[Lustre-discuss] Confusion with failover

Dhruv DhruvDesaai at gmail.com
Thu Jun 26 21:16:17 PDT 2008


Actually with my kernel of 2.6.9-22,  lustre 1.4.5.1 fits. And i am
not in position to change the OS itself.

I tried with the failover of OSTs without Linux HA. It worked fairly.
I am now testing the same rigoursly to see whether i am correct. But
the failover of MDS without HA didnt worked atall.

Can it without HA?

On Jun 27, 12:10 am, Klaus Steden <klaus.ste... at thomson.net> wrote:
> Hopefully this isn't a stupid question ... but have you considered using
> Lustre 1.6 instead, if it's an option? It's much, much easier to work with.
>
> As for failover itself ... Lustre provides redundancy in the design, i.e.
> you can have a secondary MDS that comes online when the primary has failed,
> and OSSes can assume control of one another's OSTs in case of host failure,
> but it does not implement any of this functionality. You'll have to use
> something like Linux-HA to get your server nodes to gracefully resume
> service for failed nodes.
>
> Again, I'd strongly recommend using 1.6, as the latest version of Linux-HA
> has native support for Lustre, which can use standard Linux 'mount'
> commands. If you go with 1.4, you'll have to noodle with XML and scripts
> (which will still work) which is more of a hassle, while 1.6 "just works".
>
> cheers,
> Klaus
>
> On 6/25/08 11:09 PM, "Dhruv" <DhruvDes... at gmail.com>did etch on stone
> tablets:
>
>
>
> > Hello Everybody,
> > I am a novice in using Lustre. Wanted some help.
> > I am using luster 1.4.5.1 on RHEL4 update2 with kernel 2.6.9-22. Am
> > facing some problems.
>
> > Case1:
> > I tried the ost failover . Following is the config file to generate
> > xml file.
>
> > rm -f failover_2node.xml
> > ./lmc -m failover_2node.xml --add net --node node-mds --nid sm01 --
> > nettype tcp
> > ./lmc -m failover_2node.xml --add net --node node-ost1 --nid sm02 --
> > nettype tcp
> > ./lmc -m failover_2node.xml --add net --node node-ost2 --nid sm06 --
> > nettype tcp
> > ./lmc -m failover_2node.xml --add net --node client --nid '*' --
> > nettype tcp
>
> > # Cofigure MDS
> > ./lmc -m failover_2node.xml --add mds --node node-mds --mds mds_test --
> > fstype ldiskfs --dev /dev/sdb5
>
> > # Cofigure LOV
> > ./lmc -m failover_2node.xml --add lov --lov lov_test --mds mds_test --
> > stripe_sz 1048576 --stripe_cnt 2 --stripe_pattern 0
>
> > # Configures OSTs
> > ./lmc -m failover_2node.xml --add ost --node node-ost1 --lov lov_test
> > --ost ost1 --failover --fstype ldiskfs --dev /dev/sdb1
> > ./lmc -m failover_2node.xml --add ost --node node-ost2 --lov lov_test
> > --ost ost1 --failover --fstype ldiskfs --dev /dev/sdb7
>
> > # Configure client (this is a 'generic' client used for all client
> > mounts)
> > ./lmc -m failover_2node.xml --add mtpt --node client --path /mnt/
> > lustre --mds mds_test --lov lov_test
>
> > .
> > Following were my lconf commands.
>
> > 1. lconf --reformat --node node-ost1 failover_2node.xml   .... on sm02
> > 2. lconf --reformat --node node-ost2 --service=ost1
> > failover_2node.xml .... on sm06
> > 3. lconf --reformat --node node-mds failover_2node.xml.... on sm01
> > 4. lconf --node client failover_2node.xml ... on sm02 and sm06
>
> > So my intention is to keep a failover ost node incase one fails. MDS
> > is on a seperate node. I tried different scenarios where one ost goes
> > down and still data can be retrieved from other. New files can be
> > created and old can be deleted on the failover ost. Data was available
> > most of time.
>
> > So my question is whether Linux HA required to configure such failover
> > scenario?
>
> > Case2:
> > I tried with same sort of formula as shown above for a failover MDS.
> > But when the main MDS fails, it doesnt switches to new MDS. Also when
> > the main MDS comes up again, the file system doesnt recover. I brought
> > down the client and again brought up. Then it was working.
>
> > So is Linux HA or similar program necessary for configuring failover??
>
> > Dhruv
> > _______________________________________________
> > Lustre-discuss mailing list
> > Lustre-disc... at lists.lustre.org
> >http://lists.lustre.org/mailman/listinfo/lustre-discuss
>
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