It is no secret that I am a pretty big fan of excellent Linux Software RAID. Creating, assembling and rebuilding small array is fine. But, things started to get nasty when you try to rebuild or re-sync large size array. You may get frustrated when you see it is going to take 22 hours to rebuild the array. You can always increase the speed of Linux Software RAID 0/1/5/6 reconstruction using the following five tips.
The sar command collect, report, or save UNIX / Linux system activity information. It will save selected counters in the operating system to the /var/log/sa/sadd file. From the collected data, you get lots of information about your server:
- CPU utilization
- Memory paging and its utilization
- Network I/O, and transfer statistics
- Process creation activity
- All block devices activity
- Interrupts/sec etc.
sar output can be used for identifying server bottlenecks. However, analyzing information provided by sar can be difficult, so use kSar, which can take sar output and plot a nice easy to understand graph over period of time.
Red Hat Enterprise Linux v5.4 has been released and available via RHN for immediate update. The new version includes the kernel-based virtual machine (KVM) virtualization, next generation of developer features and tools including GCC 4.4, a new malloc(). Also included clustered, high-availability filesystem to support Microsoft Windows storage needs on Red Hat Enterprise Linux.
As a system admin, I need to use additional hard drives for to provide more storage space or to separate system data from user data. This procedure, adding physical block devices to virtualized guests, describes how to add a hard drive on the host to a virtualized guest using VMWare software running Linux as guest.
It is possible to add or remove a SCSI device explicitly, or to re-scan an entire SCSI bus without rebooting a running Linux VM guest. This how to is tested under Vmware Server and Vmware Workstation v6.0 (but should work with older version too). All instructions are tested on RHEL, Fedora, CentOS and Ubuntu Linux guest / hosts operating systems.
Research shows that if your web pages take longer than 5 seconds to load, you lose 50% of your viewers and sales. As a UNIX admin often end users and web developers complain about website loading speed and timings. Usually, there is nothing wrong with my servers or server farm. Fancy java script and images / flash makes site pretty slow. These tools are useful to debug performance problems for sys admins, developers and end users. Here are six tools that can analyzes web pages and tells you why they are slow. Use the following tools to:
- Make your site faster.
- Debug site problem, especially client side and server side stuff.
- Better user experience.
- Improve the web.