[Linux-cluster] Queries regarding A four node Cluster setup

[Tom Coughlan]

On Fri, 2005-06-10 at 07:12, Sachin V Renake wrote:

<snip>

> 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?

Do the following to make the QLogic driver see the new LUN:

/*
* Usage: echo "scsi-qlascan " > /proc/scsi/<driver-name>/<adapter-id>
*
* <driver-name> can be either one : qla2100/qla2200/qla2300
*
* Ex:- For qla2300 driver:
*      echo "scsi-qlascan " > /proc/scsi/qla2300/<adapter-id>
*
* <adapter-id> is the instance number of the HBA.
*
* Scan for all luns on all ports.
*/

Then do this to make the Linux SCSI midlayer see the new LUN:

* Usage: echo "scsi scan-new-devices" >/proc/scsi/scsi
*
* Scans all host adapters again to see if there are any
* new devices.


Or use this:

* Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
* with  "0 1 2 3" replaced by your "Host Channel Id Lun".
* Consider this feature BETA.

There is also this:

* Usage: echo "scsi remove-single-device 0 1 2 3" >/proc/scsi/scsi
* with  "0 1 2 3" replaced by your "Host Channel Id Lun".
* Consider this feature pre-BETA.

The reason for the "beta" warning is that there are some races in this
code, so you should not be doing this from multiple processes or while
the configuration is changing. 

This functionality is re-done a bit differently (and without the 
restriction) in RHEL 4.

Tom