Copy Linux host to new hardware
It should be noted, that there may be other steps needed, depending on the distribution. Most notably the drivers (thanks for pointing that out @ewwhite).
- Boot the new server from livecd/usb.
- Prepare partitions and bootblock on the new drives.
- Depending on setup, this could be done by copying MBR/bootblock.
- Make the filesystems.
- Do an rsync from old server to new.
- You might want to do it again to see how long will the follow-up rsync take - if its under 30 minutes, continue.
- This is the time, you can actually try, if new system boots. Just be careful not to cause any IP (or other) conflicts.
- Shutdown all services that would write to the filesystem
- Preferably reboot to livecd/usb
- Rsync data from old server to new again
- Reboot the new server and use it
Doing it this way, you still have the original server intact, so if anything goes wrong, there is an easy way back. But it requires some knowledge (grub/rsync/partitions), so I suggest doing some prep-work and testing in advance, before doing it live.
Two things:
- I would build anew and rsync data.
- Your downtime allotment/window seems to be too short. 30 minutes can work in specific situations, but shouldn't YOU be dictating the realistic downtime requirement based on what it takes to actually accomplish the work?
Depending on the data contained within each server, the amount of data churn, and your provisioning scheme, it may make sense to install the necessary OS onto the new Gen8 ProLiant and synchronize the settings and other data portions at a point where you can quiesce the data.
Perhaps make a seed copy and derive your downtime requirement from the amount of time it takes to pick up the file changes on subsequent rsyncs. If you need to accelerate the transfer process or have lots of small files, there are techniques that can help with that.
I make these types of transitions often. With similar Linux installations, you rarely need more than an accurate package list (easily obtainable via Yum or RPM), the configuration directories (e.g. /etc) and your data partitions. If you don't already have a kickstart provisioning system, you can take advantage of the /root/anaconda-ks.cfg file to get an idea of how the G7 system was built.
To answer your question about simply moving the disks, based on the specific RHEL versions you mentioned, this is absolutely possible. You can move the disks/caddies and the HP Smart Array metadata is compatible between the P410 and P420 controllers that may be in your systems. However, I would not do this without fully updating the firmware of the drives and components in the new system first.