[Linux-cluster] Queries regarding A four node Cluster setup
Sachin V Renake
sachin.renake at in.ibm.com
Fri Jun 10 11:12:59 UTC 2005
Hello Team
Need your help in following cluster setup.
---- There are four server in the cluster like server A, server B,server C
and server D.
---- Server A and server B is installed with operating system Redhat linux
As 3.0 and Beblogic application
---- Server C is installed with operating system Redhat linux As 3.0 and
Oracle database.
--- Server D is failover server which is installed with operating system
Redhat linux As 3.0 and Beblogical application and Oracle database.
--- Lvm's are created in the Hp storage box which will be the filesystems
for the application servers and database server and they are mapped to the
particular servers.
--- Server D is mapped with all the filessystems created on HP storage box
but they are not mounted in this server.
--- Filesystem which has been created in HP storage box is a pure data
which is there for application server and database servers.
--- So Server A and server B are communicating with server C which is the
Databse (Oracle) server.
--- Now the scenario will be like this from End user side.People are going
to logg in Server A or Server B or Server C as per their requirement and
they are going to read and write their respective data related to their
functions on the storage Box.
--- Clumanager is cluster management program which is to be used.
--- Filesystem in
So now ,customers ONLY requirement is that in case Server A is going down
because of some reason,people (End users) still should be in position to
continue with their Data I/O on filesystem which is lieing on HP storage
box so our cluster will function is such a way that the particular
filesystem which was mounted in Server A which now will be transfered to
Server D so i/o will not hamper.
One point i want to make clear that during such instance,as per confirmed
with customer,the partcular Beblogic application will be started by human
intervention i.e manually in Server D.
Now our queries are like this:
1. We have found that as the filesystem which has been mapped to server A
is also mapped to server D and can be mounted simultaneously in both the
servers and can be accessed and we can carry out I/O on it.So this can
lead to corruption of data and causes insecurities.Such thing is not
going to be carry out by anyone but accidently can be happened. Suppose if
server A hangs for small period of time and though cluster manager
software,the filesystem which was assigned to this server will
automatically get mounted in Failover server D .i.e Service(Resources)
will get transfered.And if Server A is alive again after that period so
Are there any possibilities that Both servers can mount and access the
Same filesystem and cause Data corruption?
Please elaborate the functionality of Watchdog utility in this case.
2. If suppose in future,if we need to add extra Luns to the existing
server which is part of cluster,from Hp storage box,so general practice is
to use commands like
rmmod qla2300---------------------------------in order to remove the
module of hba card
modproble qla2300-------------------------- in order to install module
again
But command will involve the removal of device driver means the Detachment
(Not physical) of the externally connected storage so such situtation will
be like Downtime of the server.
So query is that is there any fascility in Redhat so that Addition of new
Lun will not involve removal of the driver Module and detachment(Not
physical)of the storage so we can carry out this activity on the Fly
without disturbing the setup?
Warm Regards
Sachin Vishwanath Renake
IBM Global Services Pvt.Ltd.
The IL & FS Building,
4th Floor, "A" wing,
Bandra Kurla Complex,Bandra (E),
Mumbai 400 051.
Telephone# 56962020 Board
Ext# 2202
Email : sachin.renake at in.ibm.com
"Don't judge each day by the harverst you reap,but by the seeds you plant"
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