Everyone,
I am putting together a new mail server for our firm using a SuperMicro with Centos 7.0. When performed the install of the os, I put 16 gigs of memory in the wrong slots on the mother board which caused the SuperMicro to recognize 8 gigs instead of 16 gigs. When I installed Centos 7.0, this error made the swap file 8070 megs instead of what I would have expected to be a over 16000 megs.
I am using the default xfs file system on the other partitions. Is there a way to expand the swap file? If not, then is this problem sufficiently bad enough for me to start over with a new install. I do not want to start over unless I need to.
Thanks for you help !!!
Greg Ennis
You can grow xfs or create more swap on filesystem files ("swap in file") 15.2.2015 17.50 kirjoitti "Gregory P. Ennis" PoMec@pomec.net:
Everyone,
I am putting together a new mail server for our firm using a SuperMicro with Centos 7.0. When performed the install of the os, I put 16 gigs of memory in the wrong slots on the mother board which caused the SuperMicro to recognize 8 gigs instead of 16 gigs. When I installed Centos 7.0, this error made the swap file 8070 megs instead of what I would have expected to be a over 16000 megs.
I am using the default xfs file system on the other partitions. Is there a way to expand the swap file? If not, then is this problem sufficiently bad enough for me to start over with a new install. I do not want to start over unless I need to.
Thanks for you help !!!
Greg Ennis
CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
On 15.02.2015 16:49, Gregory P. Ennis wrote:
Everyone,
I am putting together a new mail server for our firm using a SuperMicro with Centos 7.0. When performed the install of the os, I put 16 gigs of memory in the wrong slots on the mother board which caused the SuperMicro to recognize 8 gigs instead of 16 gigs. When I installed Centos 7.0, this error made the swap file 8070 megs instead of what I would have expected to be a over 16000 megs.
I am using the default xfs file system on the other partitions. Is there a way to expand the swap file? If not, then is this problem sufficiently bad enough for me to start over with a new install. I do not want to start over unless I need to.
8G of swap should be more than enough for a 16G system unless you plan to severely over-commit memory.
Regards, Dennis
On 2015-02-15, Gregory P. Ennis PoMec@PoMec.Net wrote:
I am putting together a new mail server for our firm using a SuperMicro with Centos 7.0. When performed the install of the os, I put 16 gigs of memory in the wrong slots on the mother board which caused the SuperMicro to recognize 8 gigs instead of 16 gigs. When I installed Centos 7.0, this error made the swap file 8070 megs instead of what I would have expected to be a over 16000 megs.
You lucked out, honestly. You really don't want 8GB of swap on your system. What will most likely happen is that you'll have a process that starts running away eating memory, and it'll try to use all of that swap before the kernel's OOM killer can kick in. You will not enjoy thrashing 8GB of swap for probably hours.
Really what you should do is drastically reduce the amount of swap you have allocated, and reclaim most of that 8GB of swap space for storage filesystems. In my experience, a few hundred MB of swap is more than sufficient to be able to swap out seldom-used memory while not taking too long to OOM. If you really find a need for more swap later, you can allocate a swap file; it's slightly less efficient than a swap partition, but compared to real memory the difference will be negligible.
--keith
On Sun, 2015-02-15 at 17:37 -0800, Keith Keller wrote:
On 2015-02-15, Gregory P. Ennis PoMec@PoMec.Net wrote:
I am putting together a new mail server for our firm using a SuperMicro with Centos 7.0. When performed the install of the os, I put 16 gigs of memory in the wrong slots on the mother board which caused the SuperMicro to recognize 8 gigs instead of 16 gigs. When I installed Centos 7.0, this error made the swap file 8070 megs instead of what I would have expected to be a over 16000 megs.
You lucked out, honestly. You really don't want 8GB of swap on your system. What will most likely happen is that you'll have a process that starts running away eating memory, and it'll try to use all of that swap before the kernel's OOM killer can kick in. You will not enjoy thrashing 8GB of swap for probably hours.
Really what you should do is drastically reduce the amount of swap you have allocated, and reclaim most of that 8GB of swap space for storage filesystems. In my experience, a few hundred MB of swap is more than sufficient to be able to swap out seldom-used memory while not taking too long to OOM. If you really find a need for more swap later, you can allocate a swap file; it's slightly less efficient than a swap partition, but compared to real memory the difference will be negligible.
--keith
I am sure glad I did not start over on the installation. Thank you to everyone for the information and education!!!!!
Thanks again!!!!
Greg
A neat trick for a server with less than idea memory requirement compared to the storage it has, is a pile of swap on an SSD. Having xfs_repair use swap on SSD is a lot faster than its fallback behavior when memory is low and there's no swap. Whereas swapping to a HDD... brutal.
Chris Murphy
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Chris Murphy -
Dennis Jacobfeuerborn -
Eero Volotinen -
Gregory P. Ennis -
Keith Keller