Noob question… Want to transition to a new computer, and updated version of Fedora. Currently have Fedora OS on a 2-HDD RAID mirror, and my /home directory on a separate 2-HDD RAID mirror; the /home directory has a handful of users.
New computer will have 2 new HDDs in RAID mirror to install Fedora, and wondering if I can just take the /home HDDs from the old computer to the new computer and set them up as RAID in the BIOS without erasing any data ? and then assigning this existing /home to the /home partition during the new Fedora installation ?
Or would I be better off backing up the /home directory to a separate disk, and then copying everything to the new /home partition once the various users are created ?
You said you have several users. As such you will need to identify those users and recreate them if doing a new install, then make sure each users directory has the proper ownership after restoring the /home data to the new PC.
Why not simply relocate the HDDs (2 different raid mirror groups) to the new PC and do an upgrade with everything already configured? (I assume the raid mirrors you mention are managed by mdadm). It is nearly 100% certain those drives would work in the new PC and little if any config would be required.
Using the existing HDD config and simply upgrading the OS would really be the simplest and safest.
Many thanks for the reply. The new computer will have a new and different CPU and thought that would be reason for not working if I just transfer the OS mirror disks ? Does the kernel install special options depending on the CPU present ? It would definitely be easier to do what you say if indeed it is OK to do ?..
Currently both mirrors are hardware mirrors at the BIOS level.
That may be an issue with the new mobo and CPU since the bios is different.
You have not said what the new hardware is, so I cannot be certain of anything.
Most newer systems that use bios raid are dependent upon windows drivers for the raid to function. Linux cannot even see the drives in many of those systems while configured for RAID. For the installer to see the drives they may have to be switched to AHCI in bios instead of raid.
Personally, I would install the system on a single drive (not raid) since a reinstall is easy in case of a drive failure. If you want raid then I would use mdadm to configure the mirrored pair of drives.
By default fedora now uses btrfs file system for / and /home and raid seems to not be recommended for a btrfs file system, so you might want to manually configure the file system to use ext4 or something else of your choice.
Without more info I really cannot say much more on the issue, but it certainly would be safest to have a backup of the data in /home before you begin the migration, regardless of how you choose to do it.
Thanks again. I like your suggestion to install the OS on a single drive, though dread having to re-create an installation from scratch (may need to keep notes of what all I do to customize and what extra packages I install). I do not mind working with ext4, this is my personal machine, not a “work” machine.
The old machine is indeed old (2008 vintage) Asus WS mobo, with Intel CPU and Intel RAID controller. New machine is also an Asus WS mobo with AMD Ryzen 5950x CPU and also Intel RAID controller.
Regardless, it is clear I need to backup /home, and recreate all users on new install before populating /home with all the old files.
If it has an actual hardware raid controller and not a windows bios raid then it may be simple to just migrate the existing raid arrays to the new system. Raid - mirrored is a better choice than a bare drive if you have the proper controller for it.
In times past I was able to export an array from one system then import it into another system with the hardware raid controller.
Thanks for the note, and good point, I did not know. I looked up the new mobo manual and looks like the RAID support is from the X570 chipset. It is the same for the old mobo, though different chipset – no actual RAID adapter cards.
Not sure if these are what you are calling “Windows” RAID ?
What is the actual motherboard. I can look it up here if I have the board model.
With those specs I would use a single M.2 drive for the OS and put the /home drives in on the SATA. The worst that could happen is the raid would not function, and the best is that it would. In any case you would be able to use one of the drives even without raid since they are mirrored.
What I referred to as “windows” raid are the designs (and bios) that do not allow linux to access the drives in RAID mode. As long as they function in RAID mode for linux you would be in really good shape.
From a quick look at that motherboard manual it seems you actually have a built-in bios controlled raid controller, so transferring the drives may be very simple. A backup is still the safe way to go, but you probably can do a new install of the os, copy in the users part from the old /etc/passwd, /etc/shadow, and /etc/groups, and use the original /home devices with little if any changes.
Thanks for the comments ! Hope to have the machine for many years to come, like my old one…
In the process of rounding up all the needed parts, but will back-up and do as you mention to do the swap. Will post here when I get it all done; may be a few weeks.
For what it’s worth, unless you have invested in some really expensive RAID controllers, you will always be better off using linux software RAID. This allows you to move your disks to a new motherboard without having to worry if the new firmware can use the old disks. I had run very limited tests using onboard and add-on RAID controllers, but my RAID10 “software” arrays always outperformed the “hardware” solution in every RAID operation.
