Cold Standby Server

Hi All,

I've maybe a very stupid question to ask, please kindly give me some hints on this.

I have 2 web servers running in data centre, and I'm thinking whether I can have a cold standby server (only turned on if needed) ready there as well in case any of the 2 servers break down (I mean hardware failure). What I want to achieve is that once any of the running servers goes down, I can go to the data centre and immediately swap the harddisk (provided that the hardware problem is not related to the harddisk) from the dead machine to the standby one and then get it up and running quickly, so that I can take my time and repair the dead machine.

So, is this possible? If so, what are the requirements (hard or soft raid disks? same OS required? same hardware a must? system settings?) in order to make this happen? This maybe dumb but I really appreciate for any suggestions on this issue. Thank you!

Regards,
Anthony.

ak17_hk said:

So, is this possible? If so, what are the requirements (hard or soft raid disks? same OS required? same hardware a must? system settings?) in order to make this happen? This maybe dumb but I really appreciate for any suggestions on this issue. Thank you!

Click to expand...

1) If not the same BIOS, then make sure you have no special dependencies between the kernel and the BIOS, or any special hardware (such as RAID hardware); try it first.
2) OS, system settings, etc., don't matter because they move when the drive does.
3) The network interface will have a different NIC number on each machine, and local area networks (including the one between your server(s) and your router) use NIC numbers rather than IP#s for routing, you may need to have the datacenter clear their arp-cache, or if you've got your own router, clear it yourself, before the standby machine will be visible on the 'net.

Jeff

jlasman said:

1) If not the same BIOS, then make sure you have no special dependencies between the kernel and the BIOS, or any special hardware (such as RAID hardware); try it first.
2) OS, system settings, etc., don't matter because they move when the drive does.
3) The network interface will have a different NIC number on each machine, and local area networks (including the one between your server(s) and your router) use NIC numbers rather than IP#s for routing, you may need to have the datacenter clear their arp-cache, or if you've got your own router, clear it yourself, before the standby machine will be visible on the 'net.

Jeff

Click to expand...

Dear Jeff,

Thanks for your advice, I'll have a try on that and let you know the results.

Just one more question. If I used software raid (2 identical harddisk on raid 1 configuration) on the running machine originally, and one of them breaks down, will the system still run with the remaining disk?

If not, then can I just move the working disk to the standby server to boot it up?

If yes, can I replace the dead harddisk with a new one? Will the data be automatically be propagated to the new mirror disk?

Thanks in advance!!

Anthony.

ak17_hk said:

If I used software raid (2 identical harddisk on raid 1 configuration) on the running machine originally, and one of them breaks down, will the system still run with the remaining disk?

Click to expand...

It should. Depending on how your RAID is set up you should get a notice of the broken disk as well.

If not, then can I just move the working disk to the standby server to boot it up?

Click to expand...

Maybe. We've never had to try it.

We have tried booting up with a dead drive 1 (or drive 0 should you call it that, though the BIOS doesn't), and that probably won't work either, depending on how GRUB is set up. Search the 'net for more information.

If yes, can I replace the dead harddisk with a new one? Will the data be automatically be propagated to the new mirror disk?

Click to expand...

No, you have to run a command to do it. Look for the how-tos and mini how-tos.

Jeff

jlasman said:

It should. Depending on how your RAID is set up you should get a notice of the broken disk as well.

Maybe. We've never had to try it.

We have tried booting up with a dead drive 1 (or drive 0 should you call it that, though the BIOS doesn't), and that probably won't work either, depending on how GRUB is set up. Search the 'net for more information.

No, you have to run a command to do it. Look for the how-tos and mini how-tos.

Jeff

Click to expand...

Dear Jeff,

You are very helpful and thanks for the guidelines on this!

Anthony.