nixCraft » File system http://www.cyberciti.biz/tips This is a Linux sys admin journal by Vivek about sys admin work, Linux tips & tricks, hacks, news and more. Wed, 24 Apr 2013 18:50:55 +0000 en-US hourly 1 http://wordpress.org/?v=3.5.1 HowTo: Create sar Graphs With kSar [ Identifying Linux Bottlenecks ]http://www.cyberciti.biz/tips/identifying-linux-bottlenecks-sar-graphs-with-ksar.html http://www.cyberciti.biz/tips/identifying-linux-bottlenecks-sar-graphs-with-ksar.html#comments Tue, 15 Dec 2009 06:33:21 +0000 nixCraft http://www.cyberciti.biz/tips/?p=6165 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:
  1. CPU utilization
  2. Memory paging and its utilization
  3. Network I/O, and transfer statistics
  4. Process creation activity
  5. All block devices activity
  6. 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. ]]> http://www.cyberciti.biz/tips/identifying-linux-bottlenecks-sar-graphs-with-ksar.html/feed 32 Visual Representations Of Linux File Systemshttp://www.cyberciti.biz/tips/visual-representations-of-linux-file-systems.html http://www.cyberciti.biz/tips/visual-representations-of-linux-file-systems.html#comments Tue, 16 Jun 2009 19:49:38 +0000 nixCraft http://www.cyberciti.biz/tips/?p=5079 This is an interesting visualization techniques for software analysis. From the article:
Despite being a very important part of any operating system, file systems tend to get little attention. Linux has three editions for Linux Device Drivers, another three for Understanding the Linux Kernel and two for Linux Kernel Development. The first is a detail analysis of one particular Linux Kernel tree and the second is a shorter one done over a large number of file systems from Linux Kernel 2.6.0 to 2.6.29. After that there is a small section that shows some aspects of the BSD family. After conclusions there is an appendix consisting of three things: the first one explains how the file systems for Linux were compiled, the second one shows timelines for the releases of Linux Kernel, FreeBSD, NetBSD and OpenBSD; the last is a detailed map of the external symbols of the kernel modules analyzed in the second section.

A Visual Expedition Inside the Linux File Systems]]> http://www.cyberciti.biz/tips/visual-representations-of-linux-file-systems.html/feed 4 How To Tail (View) Multiple Files on UNIX / Linux Consolehttp://www.cyberciti.biz/tips/multitail-view-multiple-files-like-tail-command.html http://www.cyberciti.biz/tips/multitail-view-multiple-files-like-tail-command.html#comments Mon, 09 Feb 2009 19:28:32 +0000 nixCraft http://www.cyberciti.biz/tips/?p=4399 tail is one of the best tool to view log files in a real time (tail -f /path/to/log.file). The program MultiTail lets you view one or multiple files like the original tail program. The difference is that it creates multiple windows on your console (with ncurses). This is one of those dream come true program for UNIX sys admin job. You can browse through several log files at once and do various operations like search for errors and much more.]]> http://www.cyberciti.biz/tips/multitail-view-multiple-files-like-tail-command.html/feed 13 BASH Shell: For Loop File Names With Spaceshttp://www.cyberciti.biz/tips/handling-filenames-with-spaces-in-bash.html http://www.cyberciti.biz/tips/handling-filenames-with-spaces-in-bash.html#comments Tue, 09 Dec 2008 19:18:29 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3878 BASH for loop works nicely under UNIX / Linux / Windows and OS X while working on set of files. However, if you try to process a for loop on file name with spaces in them you are going to have some problem. for loop uses $IFS variable to determine what the field separators are. By default $IFS is set to the space character. There are multiple solutions to this problem.]]> http://www.cyberciti.biz/tips/handling-filenames-with-spaces-in-bash.html/feed 56 Linux: Boot a 2TB+ partition or Larger Array Using Grubhttp://www.cyberciti.biz/tips/howto-linux-boot-2tb-larger-raidarray-harddisk.html http://www.cyberciti.biz/tips/howto-linux-boot-2tb-larger-raidarray-harddisk.html#comments Thu, 04 Dec 2008 07:13:58 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3718 I've already written about creating a partition size larger than 2TB under Linux using GNU parted command with GPT. In this tutorial, I will provide instructions for booting to a flat 2TB or larger RAID array under Linux using the GRUB boot loader.]]> http://www.cyberciti.biz/tips/howto-linux-boot-2tb-larger-raidarray-harddisk.html/feed 3 Linux: Should You Use Twice the Amount of Ram as Swap Space?http://www.cyberciti.biz/tips/linux-swap-space.html http://www.cyberciti.biz/tips/linux-swap-space.html#comments Wed, 19 Nov 2008 08:50:49 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3586 Linux and other Unix-like operating systems use the term "swap" to describe both the act of moving memory pages between RAM and disk, and the region of a disk the pages are stored on. It is common to use a whole partition of a hard disk for swapping. However, with the 2.6 Linux kernel, swap files are just as fast as swap partitions. Now, many admins (both Windows and Linux/UNIX) follow an old rule of thumb that your swap partition should be twice the size of your main system RAM. Let us say I've 32GB RAM, should I set swap space to 64 GB? Is 64 GB of swap space really required? How big should your Linux / UNIX swap space be? ]]> http://www.cyberciti.biz/tips/linux-swap-space.html/feed 64 Linux / UNIX: Find Out If a Directory Exists or Nothttp://www.cyberciti.biz/tips/find-out-if-directory-exists.html http://www.cyberciti.biz/tips/find-out-if-directory-exists.html#comments Sun, 16 Nov 2008 17:13:15 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3560 I've already written a small tutorial about finding out if a file exists or not under Linux / UNIX bash shell. However, couple of our regular readers like to know more about a directory checking using if and test shell command. ]]> http://www.cyberciti.biz/tips/find-out-if-directory-exists.html/feed 4 mount forcedirectio: Disable Linux CIFS / NFS Client Cachinghttp://www.cyberciti.biz/tips/disable-caching-on-the-cifs-nfs-client.html http://www.cyberciti.biz/tips/disable-caching-on-the-cifs-nfs-client.html#comments Sun, 16 Nov 2008 09:03:15 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3551 If your network is heavily loaded you may see some problem with Common Internet File System (CIFS) and NFS under Linux. By default Linux CIFS mount command will try to cache files open by the client. You can use mount option forcedirectio when mounting the CIFS filesystem to disable caching on the CIFS client. This is tested with NETAPP and other storage devices and Novell, CentOS, UNIX and Red Hat Linux systems. This is the only way to avoid data mis-compare and problems.]]> http://www.cyberciti.biz/tips/disable-caching-on-the-cifs-nfs-client.html/feed 2 Parallel NFS: Read / Write Hundreds of Gigabytes Per Secondhttp://www.cyberciti.biz/tips/linux-unix-parallel-nfs.html http://www.cyberciti.biz/tips/linux-unix-parallel-nfs.html#comments Thu, 13 Nov 2008 12:17:31 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3519 NFS is pretty old file sharing technology for UNIX based system and storage systems. However, it suffers from performance issues. NFSv4.1 address data access issues by adding a new feature called parallel NFS (pNFS) - a method of introducing Data Access Parallelism. The end result is ultra fast file sharing for clusters and high availability configurations.

The Network File System (NFS) is a stalwart component of most modern local area networks (LANs). But NFS is inadequate for the demanding input- and output-intensive applications commonly found in high-performance computing -- or, at least it was. The newest revision of the NFS standard includes Parallel NFS (pNFS), a parallelized implementation of file sharing that multiplies transfer rates by orders of magnitude. ]]> http://www.cyberciti.biz/tips/linux-unix-parallel-nfs.html/feed 2 Linux tgtadm: Setup iSCSI Target ( SAN )http://www.cyberciti.biz/tips/howto-setup-linux-iscsi-target-sanwith-tgt.html http://www.cyberciti.biz/tips/howto-setup-linux-iscsi-target-sanwith-tgt.html#comments Tue, 11 Nov 2008 02:39:48 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3485 Linux target framework (tgt) aims to simplify various SCSI target driver (iSCSI, Fibre Channel, SRP, etc) creation and maintenance. The key goals are the clean integration into the scsi-mid layer and implementing a great portion of tgt in user space.
The developer of IET is also helping to develop Linux SCSI target framework (stgt) which looks like it might lead to an iSCSI target implementation with an upstream kernel component. iSCSI Target can be useful:

a] To setup stateless server / client (used in diskless setups).
b] Share disks and tape drives with remote client over LAN, Wan or the Internet.
c] Setup SAN - Storage array.
d] To setup loadbalanced webcluser using cluster aware Linux file system etc.

In this tutorial you will learn how to have a fully functional Linux iSCSI SAN using tgt framework.]]> http://www.cyberciti.biz/tips/howto-setup-linux-iscsi-target-sanwith-tgt.html/feed 26 How To Use vi as Default Editor and Viewer in Midnight Commanderhttp://www.cyberciti.biz/tips/midnightcommander-set-vi-as-default-editor-viewer.html http://www.cyberciti.biz/tips/midnightcommander-set-vi-as-default-editor-viewer.html#comments Mon, 03 Nov 2008 05:01:50 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3361 Midnight Commander (mc) is an user-friendly text-based file manager UI for Unix. Using mc, you can browse the filesystem easily and manipulate the files and directories quickly. You will not miss the standard command line prompt, which is also available within the mc itself. If you are new to mc, Midnight Commander (mc) Guide: Powerful Text based File Manager for Unix article will give you a quick jumpstart. In this article, let us review how to solve couple of common annoyance about viewing a file in mc.]]> http://www.cyberciti.biz/tips/midnightcommander-set-vi-as-default-editor-viewer.html/feed 9 RAID 5 vs RAID 10: Recommended RAID For Safety and Performancehttp://www.cyberciti.biz/tips/raid5-vs-raid-10-safety-performance.html http://www.cyberciti.biz/tips/raid5-vs-raid-10-safety-performance.html#comments Wed, 22 Oct 2008 12:48:43 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3155 A Redundant Array of Independent Drives (or Disks), also known as Redundant Array of Inexpensive Drives (or Disks) (RAID) is an term for data storage schemes that divide and/or replicate data among multiple hard drives. RAID can be designed to provide increased data reliability or increased I/O performance, though one goal may compromise the other. There are 10 RAID level. But which one is recommended for data safety and performance considering that hard drives are commodity priced? ]]> http://www.cyberciti.biz/tips/raid5-vs-raid-10-safety-performance.html/feed 71 Seagate Barracuda: 1.5TB Hard Drive Launchedhttp://www.cyberciti.biz/tips/seagates-barracuda-15tb-hard-disk.html http://www.cyberciti.biz/tips/seagates-barracuda-15tb-hard-disk.html#comments Tue, 21 Oct 2008 18:53:46 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3149 Wow, this is a large size desktop hard disk for storing movies, tv shows, music / mp3s, and photos. You can also load multiple operating systems using vmware or other software for testing purpose. This hard disk comes with 5 year warranty and can transfer at 300MB/s. But, How reliable is the 1.5TB hard disk?]]> http://www.cyberciti.biz/tips/seagates-barracuda-15tb-hard-disk.html/feed 1 Sun Solaris on its Deathbed – Claims Jim Zemlinhttp://www.cyberciti.biz/tips/is-sun-solaris-on-its-deathbed.html http://www.cyberciti.biz/tips/is-sun-solaris-on-its-deathbed.html#comments Thu, 25 Sep 2008 08:23:48 +0000 nixCraft http://www.cyberciti.biz/tips/?p=2955 Jim Zemlin is executive director of the Linux Foundation claims Solaris UNIX is irrelevant and Linux is future. Is Sun Solaris on its deathbed? Linux backers claim Solaris is irrelevant; Sun of course disagrees.]]> http://www.cyberciti.biz/tips/is-sun-solaris-on-its-deathbed.html/feed 10 CentOS / Red Hat Enterprise Linux 5.2 Poor NFS Performance and Solutionhttp://www.cyberciti.biz/tips/centos-rhel-poor-nfs-write-performance.html http://www.cyberciti.biz/tips/centos-rhel-poor-nfs-write-performance.html#comments Fri, 22 Aug 2008 09:41:58 +0000 nixCraft http://www.cyberciti.biz/tips/?p=2759 A few days ago I noticed that NFS performance between a web server node and NFS server went down by 50%. NFS was optimized and the only thing was updated Red Hat kernel v5.2. I also noticed same trend on CentOS 5.2 64 bit edition.]]> http://www.cyberciti.biz/tips/centos-rhel-poor-nfs-write-performance.html/feed 4 Exporting Networked File Systems Via Another Networked File Systemhttp://www.cyberciti.biz/tips/access-networked-file-system-mounts.html http://www.cyberciti.biz/tips/access-networked-file-system-mounts.html#comments Fri, 18 Jul 2008 10:24:24 +0000 nixCraft http://www.cyberciti.biz/tips/?p=2477 http://www.cyberciti.biz/tips/access-networked-file-system-mounts.html/feed 3 Red Hat / CentOS Linux 4: Setup Device Mapper Multipathinghttp://www.cyberciti.biz/tips/rhel-linux4-setup-device-mapper-multipathing-devicemapper.html http://www.cyberciti.biz/tips/rhel-linux4-setup-device-mapper-multipathing-devicemapper.html#comments Sun, 06 Jul 2008 06:06:29 +0000 nixCraft http://www.cyberciti.biz/tips/?p=3707 http://www.cyberciti.biz/tips/rhel-linux4-setup-device-mapper-multipathing-devicemapper.html/feed 2 How To Measure Linux Filesystem I/O Performance With iozonehttp://www.cyberciti.biz/tips/linux-filesystem-benchmarking-with-iozone.html http://www.cyberciti.biz/tips/linux-filesystem-benchmarking-with-iozone.html#comments Fri, 04 Jul 2008 09:15:40 +0000 nixCraft http://www.cyberciti.biz/tips/?p=2437 http://www.cyberciti.biz/tips/linux-filesystem-benchmarking-with-iozone.html/feed 7 Linux Configure Netconsole To Log Messages Over UDP Networkhttp://www.cyberciti.biz/tips/linux-netconsole-log-management-tutorial.html http://www.cyberciti.biz/tips/linux-netconsole-log-management-tutorial.html#comments Wed, 02 Jul 2008 10:43:23 +0000 nixCraft http://www.cyberciti.biz/tips/?p=2431 http://www.cyberciti.biz/tips/linux-netconsole-log-management-tutorial.html/feed 4 HP Releases Tru64 UNIX Advanced File System ( AdvFS ) Source Codehttp://www.cyberciti.biz/tips/download-tru64-unix-advanced-filesystem-advfs-sourcecode.html http://www.cyberciti.biz/tips/download-tru64-unix-advanced-filesystem-advfs-sourcecode.html#comments Mon, 23 Jun 2008 19:57:38 +0000 nixCraft http://www.cyberciti.biz/tips/?p=2406 http://www.cyberciti.biz/tips/download-tru64-unix-advanced-filesystem-advfs-sourcecode.html/feed 3