Tuning

Under Linux / UNIX you use lp command to print files from command prompt. lp is quite useful when GUI is not installed on Linux box to print files. The lp command is simply a front end command that calls the lpr command with appropriate options. Its main use is to allow the running of […]

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I’ve already written about finding out Linux / UNIX cpu utilization using various tools. You can use same iostat command to find out disk utilization and for monitoring system input/output device loading by observing the time the physical disks are active in relation to their average transfer rates. iostat syntax for disk utilization report iostat […]

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The open source journal has published an interesting hack. It mostly applies to high-end, multiple-disk storage: Under the right conditions (that is, with certain hardware configurations which I’ll identify later) it is possible to literally double your sequential read performance from disk. If you noticed the terrible performance of the 3Ware 9500S RAID controller and […]

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If you want the server to get rebooted automatically after kernel hit by a pain error message, try adding panic=N to /etc/sysctl.conf file. It specify kernel behavior on panic. By default, the kernel will not reboot after a panic, but this option will cause a kernel reboot after N seconds. For example following boot parameter […]

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Well, personally I’m all set to freedom and open internet culture. However, in corporate and in an academic environment you will always find abuse smart users. Large and medium size corporate institutional networks suffer now a days from “smart” users who try to get their latest Movie/soft/Music/TVShow downloaded in their office. Beside the moral/legal dispute […]

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Yesterday I wrote about increasing local port range with net.ipv4.ip_local_port_range proc file. There is also /proc/sys/kernel/pid_max file, which specifies the value at which PIDs wrap around (i.e., the value in this file is one greater than the maximum PID). The default value for this file, 32768, results in the same range of PIDs as on earlier kernels (<=2.4). The value in this file can be set to any value up to 2^22 (PID_MAX_LIMIT, approximately 4 million).

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If your Linux server is opening lots of outgoing network connection, you need to increase local port range. By default range is small. For example squid proxy server can come under fire if it runs out of ports. You can use sysctl command to to modify kernel parameters at runtime. The parameters available are those […]

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