10 Ago 16 Shared memory and huge pages
This script can be used to determine how many shared memory is used by “oracle” user’s processes, and how many huge page memory is used:
t=0; for i in `ipcs -m | grep oracle | awk ‘{print $5}’`; do echo “Oracle consumed other $i bytes”; let t=t+$i; done
echo
echo “Consumed by oracle as shared memory segments: $t bytes”
let t=t/1024
let g=t/1024/1024;
echo “Memory conversions: ~ $t kbytes | ~ $g GB”hugepagetot=`cat /proc/meminfo | grep HugePages_Total | awk -F’:’ ‘{print $2}’`
hugepagefree=`cat /proc/meminfo | grep HugePages_Free | awk -F’:’ ‘{print $2}’`
let usedhugepages=hugepagetot-hugepagefree
let totkbinhigepage=usedhugepages*2048echo “Total hugepage usage in kb: $totkbinhigepage”
04 Ago 16 Change date format to tomcat log catalina.out
If you need to change your catalina.out date and time format, you can add this line to your tomcat/conf/logging.properties:
1catalina.java.util.logging.SimpleFormatter.format=[%1$td.%1$tm.%1$tY %1$tH:%1$tM:%1$tS,%1$tL] %4$s [%2$s] %5$s %6$s %n
06 Mag 16 How to convert URI to query string parameters with mod_rewrite
You may need to convert URI levels to query string parameters, for example if want to be RESTful compliant with PHP.
Try this one:
RewriteEngine on RewriteRule ^/(\w+)/(\w+)$ /path_of_index.php?lev1=$1&lev2=$2 [QSA,L]
In this case the first URI level will be converted to a query string parameter called lev1, while the second will be converted to a query string parameter called lev2, each one with the respective values.
For example, the uri /user/list will be passed to index.php and will become index.php?lev1=user&lev2=list
An eventual query string will be passed, eventually overriding lev1 and lev2 parameters.
09 Apr 16 Getting in love with Docker Machine!!
Docker is becoming the “today standard” of lxs linux containers.
I think I will avoid learning Kubernetes to handle dockerized hosts, and I will study Docker Engine, Docker Swarm and Docker Machine and its REST APIs instead.
I started from here: https://docs.docker.com/machine/overview/
04 Nov 15 Rescan iSCSI volume after resize on linux
If you need to resize a iSCSI volume you need to:
- resize the volume on the iSCSI target (ietd)
- rescan the volume on the iSCSI initiator (open-iscsi)
- resize the fs, if any
I’ll skip the resize procedure on the target, because it depends on how it’s made (lvresize, dd, etc).
The procedure to rescan the volume on the initiator (open-iscsi) is very simple and can be accomplished online.
iscsiadm -m node -R
Then, you can grow the filesystem, if any (xfs_grofs, resize_reiserfs, resize2fs, depending on your fs type).
30 Ott 15 How to check SSL/TLS protocol for a given server
If you need to check which SSL/TLS protocol version is implemented by your webserver, you can issue the following command:
dino@dam2knb:~$ echo | openssl s_client -connect 10.38.46.137:8443 2>&1 | grep Protocol
Protocol : TLSv1.2
30 Set 15 apache [error] (13)Permission denied: Cannot create SSLMutex
On one of the servers of one of my clients, a Solaris 5.8 sparc host, apache did not want to start.
It wrote the following error message on the error_log file:
cojo1@myserver $ cat error_log
[Wed Sep 30 12:24:11 2015] [error] (13)Permission denied: Cannot create SSLMutex
The problem, in my case, was about the permissions on /tmp.
Since these machines can be accessed by hundred people, someone thought well to change /tmp permissions to 0775. Everybody knows that if whould be 1777 instead.
The lack of both the sticky bit and write permissions to other did not make apache starting for non root users.
Hope this help someone.
Ciao, Dino.
27 Gen 15 How to get the device mapper name associated to LVM logical volumes
This is how to get the device mapper name (dm-1, dm-2, etc) associated to each LVM logical volume:
lvdisplay|awk '/LV Name/{n=$3} /Block device/{d=$3; sub(".*:","dm-",d); print d,n;}'
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