Installing centos7 64 bit on centos6 32 bit machine

[ralf]

Hi,
I know there is no automatic upgrade process from CentOS 6 to 7. A fresh install is needed.
My CentOS6 machine is running raid 1: md0 is root; md1 is swap, md2 is /home and md3 is /home/user1/folder1
Can I install CentOS 7 in total on md0 and swap on md1 and then, when done, modify raid 1 again to the same setup and adding md2-md3?
In this way I can keep /home on md2 and /home/user1/folder1 on md3 as is. Is there is risk that these partitions will be overwritten during the installation process and I loose everything?
I also realize I need to make sure that user1 has the same userID as in CentOS6, to make sure the user1 files on md2 have the right properties? Correct?

Any comments to this process? Does it work?
Anything else I should think about?

Any comments or recommendations are appreciated!
Thanks.

[hunter86_bg]

First installation of CentOS 7 x86_64 is not possible on x86 hardware. Pick the x86 ISO and do the installation with that.

My CentOS6 machine is running raid 1: md0 is root; md1 is swap, md2 is /home and md3 is /home/user1/folder1
Can I install CentOS 7 in total on md0 and swap on md1 and then, when done, modify raid 1 again to the same setup and adding md2-md3?

Yes, you can install on md0/md1 and later mount md2/md3 on the proper mount points.

I also realize I need to make sure that user1 has the same userID as in CentOS6, to make sure the user1 files on md2 have the right properties? Correct?

Get the UID/GID of 'user1' before the installation and if needed (not using Identity Management) - add the user with the same UID/GID.

WARNING: ALWAYS take proper backup prior the migration.

[ralf]

Many thanks!
Just a quick follow-up question.
How do I quickly check if the hardware is x86_64 compatible?
If it shows that the hardware is x86 only, it means I can only install 32bit CentOS7 and I cannot install 64bit software on my new CentOS7?

Your input is appreciated!

[TrevorH]

If `grep --color ' lm ' /proc/cpuinfo` shows that it matches on the 'lm' flag in the cpuflags line then your processor is 64 bit capable and the 64 bit version is the best for you.

If you choose the storage page in the setup dialog during the install, you can choose from there what things get mounted on which mountpoints and whether or not they are formatted during the install.

Backups are always really good things, especially when doing installations that might end up trashing everything if you make a mistake (or one of the programmers did!).

[desertcat]

Many thanks!
Just a quick follow-up question.
How do I quickly check if the hardware is x86_64 compatible?
If it shows that the hardware is x86 only, it means I can only install 32bit CentOS7 and I cannot install 64bit software on my new CentOS7?

Your input is appreciated!

Hummm An easy guess is how OLD is your machine?!? If it is older than 7-8 years old you have a 50:50 probability you are running a CPU that is ONLY 32 bit; OTOH if your machine come out within the past 5 years the chances are good it is 64bit. If you know what your CPU is you should be able to look it up and determine if it is 64 bit compatible.

[TrevorH]

All processors, except a very few laptop chips and some Atoms, have been 64 bit capable since 2005.

[kt53]

The chipset can be both 32/64 bit capable, but for an older computer it is the chipset controller that matters.
An example is a 2007 Toshiba Satellite P205-S6337 laptop with an Intel 945GM chipset.
Even though the CPU is 64 bit capable and has Linux 64 bit installed on it, the 32 bit chipset controller limits the RAM use to 2.9 GB out of installed 4GB.
(The shared graphics memory use is 256 MB).

Another gift from Intel that recently gave you Meltdown and Spectre.

[desertcat]

The chipset can be both 32/64 bit capable, but for an older computer it is the chipset controller that matters.
An example is a 2007 Toshiba Satellite P205-S6337 laptop with an Intel 945GM chipset.
Even though the CPU is 64 bit capable and has Linux 64 bit installed on it, the 32 bit chipset controller limits the RAM use to 2.9 GB out of installed 4GB.
(The shared graphics memory use is 256 MB).

Another gift from Intel that recently gave you Meltdown and Spectre.

Hence the question about how old is his machine. If this guy is running RAID he must be running a newish computer, SATA compatible, etc. I have a couple of machines that date back to 2004, one is 64 bit, the other 32 bit. Most people are not running hand-me-down computers or computer rescues that are that old. The 64 bit machine is an ex-server/ex-workstation grade machine that is now used for backup. The 32 bit machine is an ex-Windows machine that serves as my gateway machine that is soon to be replaced by the "Trash-can Monster" which still needs a "little more work" (you know how that goes...) before it replaces the 32 bit machine. The TCM is a 10 y.o. Ex-HP Workstation that ran (past tense) Windows 7, and and was found next to the dumpster and quite DEAD. It lives again!! It is a 64 bit machine and I have already installed CentOS 7.4.

[ralf]

Thanks all for your input!
The CentOS 6.9 machine tells me in the gnome system-monitor:
Intel® Core™2 Duo Processor E7400 @2.80 GHz and looking up this CPU on Intels webpage shows:
Intel® 64 ‡ Yes
Instruction Set 64-bit

Also, the `grep --color ' lm ' /proc/cpuinfo` showed identical output (Thanks Trevor).
I am therefore convinced that the hardware is 64-bit compatible.

I will do the upgrade as recommended!

CentOS Forum is a great community!