An Old-timer Needs to Install CentOS 7

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kenmorgan
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An Old-timer Needs to Install CentOS 7

Post by kenmorgan » 2020/11/08 17:45:41

Yes, I'm now an "old timer"! I installed CentOS 6 many years again, and I did it by buying a CD from an online company who then mailed the CD to me. I think that company is now out of business. My computer has a great deal of content, including 12 Web sites I created. I have installed Apache on my computer so I can run the 12 Web sites locally as well as on the Internet. I also did all that a good number of years ago. Thus, as an "old timer" who hasn't done things like that for some years now, what is the EASIEST way I can now move from CentOS 6 to CentOS 7 without putting all my computer data in danger?

All I have done so far is to examine this CentOS page: https://www.centos.org/centos-linux/

The computer I just described is a 32-bit computer. I will also need to change my 64-bit computer from CentOS 6 to CentOS 7. The two computers are on a LinkSys router.

Thanks so much.

Ken
CentOS 6

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TrevorH
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Re: An Old-timer Needs to Install CentOS 7

Post by TrevorH » 2020/11/08 17:59:20

For CentOS 7 there is still a 32 bit edition but it is supported by "the community" rather than the CentOS core team. That means it can lag behind hte main distro and the properly supported architectures. Now might be a good time to look at that 32 bit machine and think about replacing it - after all, almost all processors made since 2005 support 64 bit apart from a few laptop chips that were 32 bit only until about 2007. That means that machine is between 13 and 15 years old and you can probably save enormous amounts of money just by switching to a newer, lower power processor that will actually run faster than that old thing. There is no 32 bit version of CentOS 8 at all.

There is also no upgrade path from one version to another.

There's also no easy way to have CentOS 6 and 7 installed at the same time because they use different grub versions so installing 7 pretty much automatically wipes out your ability to boot the older version.

I'd recommend either a new machine to replace the 32 bit one and/or a new disk to install upon. You can use BIOS options to change which one boots and thus maintain the ability to boot either just by flipping the BIOS to boot from the other disk.
CentOS 6 will die in November 2020 - migrate sooner rather than later!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
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KernelOops
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Re: An Old-timer Needs to Install CentOS 7

Post by KernelOops » 2020/11/08 21:05:20

I partly agree with TrevorH above :)

My suggestion, is to get a new machine to run in parallel, next to the old one. Install CentOS 7 or 8. Then slowly bring each website across to the new system, while fixing the things that are incompatible along the way. Once you are done, you may permanently terminate the old machine.
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jlehtone
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Re: An Old-timer Needs to Install CentOS 7

Post by jlehtone » 2020/11/09 09:00:34

What KernelOops said.

Getting a new system and migrating (copy) data is definitely "easy & safe".

kenmorgan
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Re: An Old-timer Needs to Install CentOS 7

Post by kenmorgan » 2020/11/11 21:17:26

I'm greatly embarrassed! After writing what I did here, I did more checking and pulled out the folder in my filing cabinet with all the papers and details of when I bought this computer. Here's what is important:

Purchased: 2010
Intel DP43TF System board
Intel E5400 CPU
4G memory

I checked the Intel Web site for a E5400 CPU: it is 64-bit hardware!!!!! Not 32-bit.

However, for reasons I cannot remember, I installed a CentOS-6 32-bit operating system instead of a CentOS-6 64-bit operating system. So then, of course, I installed 32-bit application programs and data (if this is correct terminology).

NOW...I would like to keep this computer and install either a CentOS-7 64-bit operating system or a CentOS-8 64-bit operating system without destroying ANY of the "stuff" I have in the computer. If this can be done, that seems to be the simplest way to move from CentOS 6 to CentOS 7 (or 8).

If there are any mistakes in my thinking here, PLEASE point them out to me--and somehow give me a solution. :)

Ken
CentOS 6

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TrevorH
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Re: An Old-timer Needs to Install CentOS 7

Post by TrevorH » 2020/11/11 21:58:31

How easy it is to migrate from one version to another depends on how you have things set up. If you have your /home on a separate filesystem then it is much easier as you can do an install and tell it to leave that alone entirely and then add it as a /home mount post-install, or you can tell it to mount it on /home during the install (just make sure you don't format it!). That handles moving data that's in your home directory and will also pull across most application settings as well since they tend to be stored there, per user.

You will need to reinstall all your apps. You may also need reconfigure them if they do not keep per user settings under /home.

There is one problem that you do need to be aware of and that is that CentOS 6 was the last version to use the Grub Legacy boot loader, newer versions use grub2 instead. They are incompatible so if you install CentOS 7 or 8 on the same disk that CentOS 6 is on now, it will wipe out your ability to boot CentOS 6. What I have done in the past to manage this is I've bought a new disk (or more accurately installed one I had lying around) and then flipped the order in which the computer BIOS tries to boot from them. That lets you do a fresh install on a new disk and keep all your old data on the old disk. You can then mount filesystems (e.g /home) from the old disk or you can copy the whole thing to a new filesystem on the new disk if that's what you prefer. You might also choose to install an SSD and speed up the entire machine that way.

You can confirm if the machine is 64 bit by running grep " lm " /proc/cpuinfo on a linux booted on there. It will show a cpu fags line with " lm " in it meaning that it supports "long mode" i.e. 64 bit.
CentOS 6 will die in November 2020 - migrate sooner rather than later!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
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Montuna
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Re: An Old-timer Needs to Install CentOS 7

Post by Montuna » 2020/11/11 22:03:33

See Trevor's suggestion about the new disk. It appears, from my reading of this thread that is your only viable option. The 7 boot grub will eat your 6 distribution. Just make sure you install the entire thing on your new disk, (I'd pull the old disk till I was finished, then plug it back in, but then I'm paranoid).

Centos 8 kicks butt, but it doesn't have maxima, hence I'm livnig in centos7 while I try to get maxima on to a VM on which I've installed centos 8. I can also boot into Centos 8, but I haven't done that for a while, as 7 does all I need and I can use Maxima w/o issues. Also, I'm a KDE junkie, and the kwallet migration (from 7 to 8) is making me leave kwallet behind when I actually can move to 8. But 8 is really sweet. (8.2 (I think) is the gcc version, and kde is very nice looking, even thought there is some extra hoops I had to jump through to get that working on 8, as I recall).

Good luck, and you may want to wait for others to agree with what I'm saying, which is to listen to Trevor's suggestion in terms of the disk.

Cheers, from another old timer

Mike

And Trevor already answered your post, so mine is superflous...

kenmorgan
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Re: An Old-timer Needs to Install CentOS 7

Post by kenmorgan » 2020/11/12 00:27:08

I'll have a number of questions coming up. But just for a start, I'll offer this question.

I opened a terminal and ran this: grep " lm " /proc/cpuinfo

The result was this:

[kmorgan@localhost1 ~]$ grep " lm " /proc/cpuinfo
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf eagerfpu pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm xsave lahf_lm dtherm pti retpoline tpr_shadow vnmi flexpriority
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf eagerfpu pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm xsave lahf_lm dtherm pti retpoline tpr_shadow vnmi flexpriority
[kmorgan@localhost1 ~]$

What is all this? :o
CentOS 6

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jlehtone
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Re: An Old-timer Needs to Install CentOS 7

Post by jlehtone » 2020/11/12 07:35:44

It is the two lines of the content of /proc/cpuinfo that contain string " lm ".
You can see all content with cat /proc/cpuinfo, but it has 26 lines per logical core.
Command lscpu shows a 25-line summary that includes the flags too:

Code: Select all

lscpu | grep " lm "
The "Wolfdale" E5400 has two physical cores and no HT. Therefore it has two logical cores and that is why you get two lines.

Flags is a list of features that the CPU has. Which instruction sets it does support and so forth. Some examples:

Code: Select all

Xeon E5620
Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 popcnt aes lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid dtherm ida arat flush_l1d

Core i7-6700K
Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp md_clear flush_l1d

Xeon Gold 6230
Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single intel_ppin ssbd mba ibrs ibpb stibp ibrs_enhanced tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts pku ospke avx512_vnni md_clear flush_l1d arch_capabilities
Since TrevorH told to look for feature lm, it must be something that 32-bit CPUs did not have.

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TrevorH
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Re: An Old-timer Needs to Install CentOS 7

Post by TrevorH » 2020/11/12 10:25:34

Since TrevorH told to look for feature lm, it must be something that 32-bit CPUs did not have.
It's "Long Mode" - i.e the ability to execute 64 bit instructions.
CentOS 6 will die in November 2020 - migrate sooner rather than later!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
Full time Geek, part time moderator. Use the FAQ Luke

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