Linux : Tunable TCP /proc parameters
cloudibee Tunable TCP settings can be found on /proc/sys/net/ipv4 . Here are the details of few of them.tcp_keepalive_probes : Number of KEEPALIVE probes tcp sends out, until the server decides that…
cloudibee
prelink: Improve your system performance.
prelink is a program which modifies ELF shared libraries and ELF dynamically linked binaries, so that the time which dynamic linker needs for their relocation at startup significantly decreases and…
sginfo : Disk information
sginfo command in Linux can be used to get information about the SCSI disks on the system. Display disk vendor, product code and firmware version : # sginfo /dev/sddDevice Type…
Performance : Throughput analysis using iozone.
The throughput of local filesystem or an nfs mount can be captured using iozone. The below command starts throughput calculation on /d1 filesystem , with 2 IO threads working on…
Linux : Virtual filesystem – Loopback device
Sometimes you may need additional local partition or local mountable drives, but you dont have free blocks in the parition table. In that case virtual filesystem helps. You can create…
NFS client : rsize wsize
The nfs client mount command options “rsize” and “wsize” specify the size of the chunks of data that the client and server pass back and forth to each other. If…
Linux : Forcing fsck on nxt boot
If you want to force fsck on the next boot, just create a file called /forcefsck . If this file is present, then during next boot – the fsck is…
Encrypting a tar file using openssl
In some cases, you may have to send your datacenter’s passwd information to some of your collegues. Instead of sending them in plain text, you can use tar & openssl…
Loadbalancer
A good presentation from F5 explaining all features of Loadbalancer : http://www.f5.com/flash/product-demo/
Download using wget
You can use “wget” on Linux machine CLI to download files from http or ftp sites. Proxy configuration can be done for wget by exporting environment variables Initialize proxy :…
Netapp : nfsstat command
This command displays the NFS and RPC statistics of filer. The command can be used to find the performance bottlenecks in NFS environment. This shows the metrics for each nfs…
How to resize Netapp Qtree Quotas .. ?
1) Get the quotas file from netapp # rsh unixfoo-nfs1 rdfile /etc/quotas > /tmp/quotas 2) Edit the quotas file and change the quota for the required qtree. # vi /tmp/quotas…
Useful AIX tips
Display paging space details # lsps -aPage Space Physical Volume Volume Group Size %Used Active Auto Typehd6 hdisk1 rootvg 8192MB 1 yes yes lv# Memory module details : # lscfg…
Linux RPM database recovery
Sometimes you may get the below error while running “rpm -qa” or any other rpm listing command. This error suggests that the RPM db is corrupted and you need to…
Increasing swap performance
If your Linux machine is configured with several swap partitions, the default trend is to use of one partition at a time. Once one swap partition has been full the…