When upgrading the Linux kernel in CentOS, is a downgrade possible afterward?
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On facing serios issues with ZFS under CentOS 7, a commenter in SuperUser has suggested the CentOS kernel is very old and I should upgrade to a new one. Question with comment.
Reading this page it suggests the new kernel is available for simple installation from the ELRepo, but it deosn't describe whether the installation is easily reverted if it happens to break my system. Will the new kernel be visible in the grub screen on startup suggesting there are previous installations I could boot into and revert to?
Important:
I have not upgraded the kernel yet, I am asking this question on the hypothetical that I do, what I can expect, and what can be done if the upgrade goes badly.
centos linux-kernel grub upgrade
asked Dec 6 '17 at 13:46
J Collins
4121415
add a comment |Â
up vote
1
down vote
favorite
On facing serios issues with ZFS under CentOS 7, a commenter in SuperUser has suggested the CentOS kernel is very old and I should upgrade to a new one. Question with comment.
Reading this page it suggests the new kernel is available for simple installation from the ELRepo, but it deosn't describe whether the installation is easily reverted if it happens to break my system. Will the new kernel be visible in the grub screen on startup suggesting there are previous installations I could boot into and revert to?
Important:
I have not upgraded the kernel yet, I am asking this question on the hypothetical that I do, what I can expect, and what can be done if the upgrade goes badly.
centos linux-kernel grub upgrade
asked Dec 6 '17 at 13:46
J Collins
4121415
@Rui F Ribeiro: Old versions of what exactly? A kernel, an OS, a module? I hadn't noticed these downvotes. Anonymous downvotes are rubbish. I am asking the question of what will happen when I install a new kernel, not what I'm looking at having installed one. Surely this is clear, but I'll fix it nonetheless.
– J Collins
Dec 6 '17 at 13:54
Just to be sure, that your system has latest Centos updates applied, what is your kernel version now?
– Jaroslav Kucera
Dec 6 '17 at 14:21
The current kernel is 3.10.0, the latest listed is 3.10.108 according to the commenter, while the latest kernel is 4.14.3 according to his link. There was no specific reason to believe this is the course of my issue, but worth trying.
– J Collins
Dec 6 '17 at 14:32
This question is becoming a bizarre batteground. Two downvotes, three upvotes, two votes to close, one deleted comment. What on earth is going on?
– J Collins
Dec 6 '17 at 14:56
1
Usually when you install a new kernel, you would have the option to boot into the older version of the kernel at boot time, so if you messed something up you can always revert, and remove the new kernel. This is on RHEL, assuming the same thing happens on Centos.
– Hunter.S.Thompson
Dec 6 '17 at 15:21
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
On facing serios issues with ZFS under CentOS 7, a commenter in SuperUser has suggested the CentOS kernel is very old and I should upgrade to a new one. Question with comment.
Reading this page it suggests the new kernel is available for simple installation from the ELRepo, but it deosn't describe whether the installation is easily reverted if it happens to break my system. Will the new kernel be visible in the grub screen on startup suggesting there are previous installations I could boot into and revert to?
Important:
I have not upgraded the kernel yet, I am asking this question on the hypothetical that I do, what I can expect, and what can be done if the upgrade goes badly.
centos linux-kernel grub upgrade
asked Dec 6 '17 at 13:46
J Collins
4121415
On facing serios issues with ZFS under CentOS 7, a commenter in SuperUser has suggested the CentOS kernel is very old and I should upgrade to a new one. Question with comment.
Reading this page it suggests the new kernel is available for simple installation from the ELRepo, but it deosn't describe whether the installation is easily reverted if it happens to break my system. Will the new kernel be visible in the grub screen on startup suggesting there are previous installations I could boot into and revert to?
Important:
I have not upgraded the kernel yet, I am asking this question on the hypothetical that I do, what I can expect, and what can be done if the upgrade goes badly.
centos linux-kernel grub upgrade
asked Dec 6 '17 at 13:46
J Collins
4121415
edited Dec 6 '17 at 13:57
asked Dec 6 '17 at 13:46
J Collins
4121415
asked Dec 6 '17 at 13:46
J Collins
4121415
asked Dec 6 '17 at 13:46
J Collins
4121415
4121415
@Rui F Ribeiro: Old versions of what exactly? A kernel, an OS, a module? I hadn't noticed these downvotes. Anonymous downvotes are rubbish. I am asking the question of what will happen when I install a new kernel, not what I'm looking at having installed one. Surely this is clear, but I'll fix it nonetheless.
– J Collins
Dec 6 '17 at 13:54
Just to be sure, that your system has latest Centos updates applied, what is your kernel version now?
– Jaroslav Kucera
Dec 6 '17 at 14:21
The current kernel is 3.10.0, the latest listed is 3.10.108 according to the commenter, while the latest kernel is 4.14.3 according to his link. There was no specific reason to believe this is the course of my issue, but worth trying.
– J Collins
Dec 6 '17 at 14:32
This question is becoming a bizarre batteground. Two downvotes, three upvotes, two votes to close, one deleted comment. What on earth is going on?
– J Collins
Dec 6 '17 at 14:56
1
Usually when you install a new kernel, you would have the option to boot into the older version of the kernel at boot time, so if you messed something up you can always revert, and remove the new kernel. This is on RHEL, assuming the same thing happens on Centos.
– Hunter.S.Thompson
Dec 6 '17 at 15:21
add a comment |Â
@Rui F Ribeiro: Old versions of what exactly? A kernel, an OS, a module? I hadn't noticed these downvotes. Anonymous downvotes are rubbish. I am asking the question of what will happen when I install a new kernel, not what I'm looking at having installed one. Surely this is clear, but I'll fix it nonetheless.
– J Collins
Dec 6 '17 at 13:54
Just to be sure, that your system has latest Centos updates applied, what is your kernel version now?
– Jaroslav Kucera
Dec 6 '17 at 14:21
The current kernel is 3.10.0, the latest listed is 3.10.108 according to the commenter, while the latest kernel is 4.14.3 according to his link. There was no specific reason to believe this is the course of my issue, but worth trying.
– J Collins
Dec 6 '17 at 14:32
This question is becoming a bizarre batteground. Two downvotes, three upvotes, two votes to close, one deleted comment. What on earth is going on?
– J Collins
Dec 6 '17 at 14:56
1
Usually when you install a new kernel, you would have the option to boot into the older version of the kernel at boot time, so if you messed something up you can always revert, and remove the new kernel. This is on RHEL, assuming the same thing happens on Centos.
– Hunter.S.Thompson
Dec 6 '17 at 15:21
@Rui F Ribeiro: Old versions of what exactly? A kernel, an OS, a module? I hadn't noticed these downvotes. Anonymous downvotes are rubbish. I am asking the question of what will happen when I install a new kernel, not what I'm looking at having installed one. Surely this is clear, but I'll fix it nonetheless.
– J Collins
Dec 6 '17 at 13:54
@Rui F Ribeiro: Old versions of what exactly? A kernel, an OS, a module? I hadn't noticed these downvotes. Anonymous downvotes are rubbish. I am asking the question of what will happen when I install a new kernel, not what I'm looking at having installed one. Surely this is clear, but I'll fix it nonetheless.
– J Collins
Dec 6 '17 at 13:54
Just to be sure, that your system has latest Centos updates applied, what is your kernel version now?
– Jaroslav Kucera
Dec 6 '17 at 14:21
Just to be sure, that your system has latest Centos updates applied, what is your kernel version now?
– Jaroslav Kucera
Dec 6 '17 at 14:21
The current kernel is 3.10.0, the latest listed is 3.10.108 according to the commenter, while the latest kernel is 4.14.3 according to his link. There was no specific reason to believe this is the course of my issue, but worth trying.
– J Collins
Dec 6 '17 at 14:32
The current kernel is 3.10.0, the latest listed is 3.10.108 according to the commenter, while the latest kernel is 4.14.3 according to his link. There was no specific reason to believe this is the course of my issue, but worth trying.
– J Collins
Dec 6 '17 at 14:32
This question is becoming a bizarre batteground. Two downvotes, three upvotes, two votes to close, one deleted comment. What on earth is going on?
– J Collins
Dec 6 '17 at 14:56
This question is becoming a bizarre batteground. Two downvotes, three upvotes, two votes to close, one deleted comment. What on earth is going on?
– J Collins
Dec 6 '17 at 14:56
1
1
Usually when you install a new kernel, you would have the option to boot into the older version of the kernel at boot time, so if you messed something up you can always revert, and remove the new kernel. This is on RHEL, assuming the same thing happens on Centos.
– Hunter.S.Thompson
Dec 6 '17 at 15:21
Usually when you install a new kernel, you would have the option to boot into the older version of the kernel at boot time, so if you messed something up you can always revert, and remove the new kernel. This is on RHEL, assuming the same thing happens on Centos.
– Hunter.S.Thompson
Dec 6 '17 at 15:21
add a comment |Â
1 Answer
1
active
oldest
votes
up vote
2
down vote
accepted
You should consider installing the new kernel, versus upgrading your present kernel. "Installing" and "upgrading" are not (or are not necessarily) synonymous. Installing the new kernel will keep your existing kernel(s) and by default the previous kernel(s) will be shown on the grub menu, and if the new kernel doesn't work as needed, you can reboot and start with a prior kernel. yum install kernel and yum update kernel will perform an install of the new kernel this way. rpm -U, where the -U is for "upgrade," will not - it will overwrite the existing kernel, and if that "new and improved" kernel doesn't work, you may not have a fallback.
answered Dec 6 '17 at 14:56
Bob in FWB
464
Excellent! Will youryum install kernelandyum update kernel, in that order, upgrade the kernel beyond what is available in the CentOS repository so long as ELRepo is available?
– J Collins
Dec 6 '17 at 14:59
1
You can use either of the 'yum' commands - in this case they both do the same thing (but running both should do no harm, and the second should report there's nothing to install/update). It/they should get the latest version of the kernel from the repositories configured on your system, so if ELRepo has a newer kernel than the CentOS repo, that will be installed.
– Bob in FWB
Dec 6 '17 at 16:13
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
accepted
You should consider installing the new kernel, versus upgrading your present kernel. "Installing" and "upgrading" are not (or are not necessarily) synonymous. Installing the new kernel will keep your existing kernel(s) and by default the previous kernel(s) will be shown on the grub menu, and if the new kernel doesn't work as needed, you can reboot and start with a prior kernel. yum install kernel and yum update kernel will perform an install of the new kernel this way. rpm -U, where the -U is for "upgrade," will not - it will overwrite the existing kernel, and if that "new and improved" kernel doesn't work, you may not have a fallback.
answered Dec 6 '17 at 14:56
Bob in FWB
464
Excellent! Will youryum install kernelandyum update kernel, in that order, upgrade the kernel beyond what is available in the CentOS repository so long as ELRepo is available?
– J Collins
Dec 6 '17 at 14:59
1
You can use either of the 'yum' commands - in this case they both do the same thing (but running both should do no harm, and the second should report there's nothing to install/update). It/they should get the latest version of the kernel from the repositories configured on your system, so if ELRepo has a newer kernel than the CentOS repo, that will be installed.
– Bob in FWB
Dec 6 '17 at 16:13
add a comment |Â
up vote
2
down vote
accepted
You should consider installing the new kernel, versus upgrading your present kernel. "Installing" and "upgrading" are not (or are not necessarily) synonymous. Installing the new kernel will keep your existing kernel(s) and by default the previous kernel(s) will be shown on the grub menu, and if the new kernel doesn't work as needed, you can reboot and start with a prior kernel. yum install kernel and yum update kernel will perform an install of the new kernel this way. rpm -U, where the -U is for "upgrade," will not - it will overwrite the existing kernel, and if that "new and improved" kernel doesn't work, you may not have a fallback.
answered Dec 6 '17 at 14:56
Bob in FWB
464
Excellent! Will youryum install kernelandyum update kernel, in that order, upgrade the kernel beyond what is available in the CentOS repository so long as ELRepo is available?
– J Collins
Dec 6 '17 at 14:59
1
You can use either of the 'yum' commands - in this case they both do the same thing (but running both should do no harm, and the second should report there's nothing to install/update). It/they should get the latest version of the kernel from the repositories configured on your system, so if ELRepo has a newer kernel than the CentOS repo, that will be installed.
– Bob in FWB
Dec 6 '17 at 16:13
add a comment |Â
up vote
2
down vote
accepted
up vote
2
down vote
accepted
You should consider installing the new kernel, versus upgrading your present kernel. "Installing" and "upgrading" are not (or are not necessarily) synonymous. Installing the new kernel will keep your existing kernel(s) and by default the previous kernel(s) will be shown on the grub menu, and if the new kernel doesn't work as needed, you can reboot and start with a prior kernel. yum install kernel and yum update kernel will perform an install of the new kernel this way. rpm -U, where the -U is for "upgrade," will not - it will overwrite the existing kernel, and if that "new and improved" kernel doesn't work, you may not have a fallback.
answered Dec 6 '17 at 14:56
Bob in FWB
464
You should consider installing the new kernel, versus upgrading your present kernel. "Installing" and "upgrading" are not (or are not necessarily) synonymous. Installing the new kernel will keep your existing kernel(s) and by default the previous kernel(s) will be shown on the grub menu, and if the new kernel doesn't work as needed, you can reboot and start with a prior kernel. yum install kernel and yum update kernel will perform an install of the new kernel this way. rpm -U, where the -U is for "upgrade," will not - it will overwrite the existing kernel, and if that "new and improved" kernel doesn't work, you may not have a fallback.
answered Dec 6 '17 at 14:56
Bob in FWB
464
answered Dec 6 '17 at 14:56
Bob in FWB
464
answered Dec 6 '17 at 14:56
Bob in FWB
464
answered Dec 6 '17 at 14:56
Bob in FWB
464
464
Excellent! Will youryum install kernelandyum update kernel, in that order, upgrade the kernel beyond what is available in the CentOS repository so long as ELRepo is available?
– J Collins
Dec 6 '17 at 14:59
1
You can use either of the 'yum' commands - in this case they both do the same thing (but running both should do no harm, and the second should report there's nothing to install/update). It/they should get the latest version of the kernel from the repositories configured on your system, so if ELRepo has a newer kernel than the CentOS repo, that will be installed.
– Bob in FWB
Dec 6 '17 at 16:13
add a comment |Â
Excellent! Will youryum install kernelandyum update kernel, in that order, upgrade the kernel beyond what is available in the CentOS repository so long as ELRepo is available?
– J Collins
Dec 6 '17 at 14:59
1
You can use either of the 'yum' commands - in this case they both do the same thing (but running both should do no harm, and the second should report there's nothing to install/update). It/they should get the latest version of the kernel from the repositories configured on your system, so if ELRepo has a newer kernel than the CentOS repo, that will be installed.
– Bob in FWB
Dec 6 '17 at 16:13
Excellent! Will your
yum install kernel and yum update kernel, in that order, upgrade the kernel beyond what is available in the CentOS repository so long as ELRepo is available?– J Collins
Dec 6 '17 at 14:59
Excellent! Will your
yum install kernel and yum update kernel, in that order, upgrade the kernel beyond what is available in the CentOS repository so long as ELRepo is available?– J Collins
Dec 6 '17 at 14:59
1
1
You can use either of the 'yum' commands - in this case they both do the same thing (but running both should do no harm, and the second should report there's nothing to install/update). It/they should get the latest version of the kernel from the repositories configured on your system, so if ELRepo has a newer kernel than the CentOS repo, that will be installed.
– Bob in FWB
Dec 6 '17 at 16:13
You can use either of the 'yum' commands - in this case they both do the same thing (but running both should do no harm, and the second should report there's nothing to install/update). It/they should get the latest version of the kernel from the repositories configured on your system, so if ELRepo has a newer kernel than the CentOS repo, that will be installed.
– Bob in FWB
Dec 6 '17 at 16:13
add a comment |Â
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@Rui F Ribeiro: Old versions of what exactly? A kernel, an OS, a module? I hadn't noticed these downvotes. Anonymous downvotes are rubbish. I am asking the question of what will happen when I install a new kernel, not what I'm looking at having installed one. Surely this is clear, but I'll fix it nonetheless.
– J Collins
Dec 6 '17 at 13:54
Just to be sure, that your system has latest Centos updates applied, what is your kernel version now?
– Jaroslav Kucera
Dec 6 '17 at 14:21
The current kernel is 3.10.0, the latest listed is 3.10.108 according to the commenter, while the latest kernel is 4.14.3 according to his link. There was no specific reason to believe this is the course of my issue, but worth trying.
– J Collins
Dec 6 '17 at 14:32
This question is becoming a bizarre batteground. Two downvotes, three upvotes, two votes to close, one deleted comment. What on earth is going on?
– J Collins
Dec 6 '17 at 14:56
1
Usually when you install a new kernel, you would have the option to boot into the older version of the kernel at boot time, so if you messed something up you can always revert, and remove the new kernel. This is on RHEL, assuming the same thing happens on Centos.
– Hunter.S.Thompson
Dec 6 '17 at 15:21