Need our opinions

[Ulrich Tehrani]

Hello,


I am thinking on a cold standby solution with too HP D Class servers. One is a D200 the other is a D270 server. If the active system has a hardware failure - (disks failures will be handled by Mirrordisk). If other hardware fail i will swap the disks from the failed system to the standby system.

A big problem are maybe software licenses wired to the hardware.

Which problems can also occur ?
Need our opinions.


Thanks in advance


Uli

[Mark Grant]

Have you considered ServiceGuard. It is designed exactly for this.

If you keep your standby machine off the network, you will only have license issues with applications that license against the machine id.

Most applications don't do this though.

You are better off getting storage that can be used by both machines though as this makes your options much more flexible.

[Steven E. Protter]

I don't think you have a licensing issue. If the production machine has licenses for all processors, you have the right to shift production to another machine without another license. You can't run the software on both at the same time.

I would suggest Serviceguard as a clustering solution except the hardware is old and is either no longer supported or will soon be out of support.

Its up to you to be sure the disks will work in both systems, if not, your plan will fail.

You need to have a DR test and see if this scenario will work, because the hardware is pretty out of date/

SEP

[Sridhar Bhaskarla]

Hi Uli,

YOu have to be very careful if you are planning to do it. What you are trying to is to mimic serviceguard. If you can pay some money you can get serviceguard that can eliminate a lot of headaches. Otherwise, you will need to make sure the VGs are not activated at the same time by customizing the /etc/lvmrc file. Also you will need to take care of network and other stuff. This may involve quite a bit of scripting with meticulous error handling.

-Sri

[Victor BERRIDGE]

Hi,
What kind of disk configuration are you on?
Internal hotswap? external cabinet?...
You shoulnd have too much problems here nor licence issues (HPUX that is, for you did not mention what else is running...).
I may see an issue in swapping the disks (system), my concern is about the 2 systems, what lan interface are you using? at the time of D200-210 extra lan cards used vglan drivers... then btlan ...
I would suggest to test in booting straight away in single user and check the lan config before to go multi-user and have bad surprise...
Dont forget in /etc/nswitch.conf to put files first...

For the rest I did such configs a few years ago without suffering (internal hotswap system disk+ external scsi-subsystem with D220-D230)

good luck
Victor

[Bill Hassell · Accepted solution]

The real issues will be with I/O. The two systems must have EXACTLY the same I/O cards in EXACTLY the same slots. The way to verify this is to run ioscan -kf on both systems and compare line by line. The device files on the two systems may be different depending on the order you added devices but this is only relevant to the current installation. Since you replacing the opsystem disks, the device files will still point to the same hardware paths.

As far as licensing, this is *always* application dependent. Some applications license based on the MAC address of the first working LAN card. Others (more common) use the output of uname -i which *WILL* be different on the two machines. Still others look at uname -m which will be different. And arp caches in network appliances and other machines may be confused since the same IP address now has a different MAC address--this is probably not a big issue except for some clunky boxes.

I would perform a dress rehearsal for your potential disaster. This means that during some scheduled downtime, actually move the disks to your backup machine and bootup to test your entire environment. Even better: switch machines every few weeks or so. But the best choice is ServiceGuard.

[Ulrich Tehrani]

Thank you all for your support


Rgds

Uli