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May
15
awarded  Commentator
May
15
comment What does eno mean in network interface name 'eno16777736' for CentOS 7 or RHEL 7?
It's not always the same, either - I have eno16780032. What a pain in the ass.
Mar
18
comment Do I need swap space if I have more than enough amount of RAM?
(non-transparent) hugepages may not be usable by your app. Typically apps that need tons of memory can use them; e.g., database servers, java jvm. They must be explicitly enabled, and they become a separate memory pool that can't be used for other purposes. THis may be good or may be bad, depending on your circumstances. Also, learn about Transparent hugepages. These attempt to move things around so that you're using hugepages (for their performance improvement) even though your apps don't know how. If memory is fragmented things can go south as the hugepage sweeper has more to do.
Mar
18
comment Do I need swap space if I have more than enough amount of RAM?
One downside - imagine that your disk storage is slow. I'm thinking of a case where I had a vmware installation with VM storage on an ISCSI SAN. SAN was connected via 1GE. We had plenty of IOPS but not a ton of bandwidth. If a VM started swapping heavily due to a runaway application, the only reasonable course of action was usually a hard reboot - it was so slow to get logged in, and the server was hosed anyway. We changed things so that we had small swap partitions, and let the OOM killer take over much sooner.
Feb
13
revised Screen in bash script
clarificatin
Feb
5
awarded  Yearling
Feb
4
comment Rsync filter: copying one pattern only
Note that rsync's patterns used in the include and exclude filters also have a ** that does the same thing. You can escape *'s from other shells by putting them in quotation marks.
Jan
16
comment Java “Could not reserve enough space for object heap” even though there is enough RAM
This fixed my problem. I wasn't on a virtual server, rather on hardware with 80G of RAM. The server is new and not used yet, so all that memory was available. The default system memory limit of 16GB caused me to be unable to start the JVM. Even as root. Modifying /etc/security/limits.conf fixed the problem. RHEL6.6.
Dec
9
awarded  Critic
Nov
12
comment Why is Linux NFS server implemented in the kernel as opposed to userspace?
Readers should note that Bruce is (a? the?) maintainer of the linux NFS server, so presumably he knows what he is talking about. :)
Oct
6
comment Does 'ulimit -m' not work on (modern) Linux?
Here's an interesting article which goes into some detail about the various limits and what they mean. It's ten years old but presumably most of this stuff doesn't change. answers.google.com/answers/threadview/id/311442.html
Aug
15
comment How to find out what version of RHEL I'm using?
See also serverfault.com/questions/89654/what-version-of-rhel-am-i-using - there's a tip for doing it with RPM when lsb is not installed.
Dec
9
revised Screen in bash script
added 146 characters in body
Dec
9
answered Screen in bash script
Oct
3
comment How to force 'yum search' to use local metadata/cache?
It's not entirely true that yum caches are disabled by default. the package cache is disabled, but the metadata is cached by default. yum -C as you mention uses that locally cached metadata.
Aug
13
awarded  Necromancer
Jul
9
comment dhcpd: any way to check dhcp pool status?
On X random linux distro, the location of the lease file is probably defined in the dhcpd.conf file. It might possibly use the compiled-in default though. The config file usually lives under /etc (although perhaps in a subdirectory; red hat puts it in /etc/dhcp/dhcpd.conf).
Apr
1
revised Should LVM partitions be used in virtual machine images?
add paragraph mentioning that AWS does not make it easy to resize virtual disks
Feb
17
revised Should LVM partitions be used in virtual machine images?
add bit about partition alignment.
Jan
23
awarded  Custodian