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Special Forums Hardware Filesystems, Disks and Memory iostat output vs TPC output (array layer) Post 302517362 by DGPickett on Tuesday 26th of April 2011 02:59:55 PM
Old 04-26-2011
Well, it is a complex world, with security and speed in opposition. One oddity of expanding sidk sizes is that one new big disk may be overwhelmed with the level of I/O that used to be handled by 8 disks, so size attracting query and churn is a negative! Striping allows the bandwidth of many drives to be applied to the combined storage, with supports more buffering with faster buffer fills, if things are sequential often enough. If everything was sequential and failure was no worry, you could stipe all together for max bandwidth, but you might do better with 2 or more virtual volumes so copying, database joining and such can be sequential on each virtual device. So, there are sometimes ways to force smart parallelism, the ability to join huge sets without seeks. However, RAM and 64 bit VM have made buffering so ample that it may dilute that sort of approach. RAID has not entirely freed us from failure worry, since with all the layers of software and hardware and vendors, it seems RAID errors often never get heard until they are 2 devices down. Rebuild time is not inconsequential, either. So, your approach should go beyond hot spots to maximizing the bandwidth of a managable number of virtual volumes. Along the way, look at the pathways and how they figure into the redundancy and striping. If a controller handles both sides of a mirror, and goes wonky . . . . If striping runs across all controllers, scsi cables, then any controller or cable bottleneck is diluted. Intellegent use of simple mirror for high churn and RAID-N for low churn is nice, too! Sometimes, this discussion can be extended down into the app, as DB2 append tables with insert never update or delete are churn free except at the end. Disk is cheap and 100% history is wise. Churn-free data might even migrate to some hierarchical read-only store like DVD arrays. Assuming control of chaos is someone else's job can be a luxury.

But, yeah, it seems like it is still good, but might not be sufficient, and an approach with sufficiency might not make it necessary.
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dxdw(8) 						      System Manager's Manual							   dxdw(8)

NAME
dxdw - Runs and repeats command line commands SYNOPSIS
/usr/bin/X11/dxdw [-c initial_command] OPTIONS
Specifies the command to run. The command string must be enclosed in double quotes if it contains any spaces or special characters inter- preted by the shell. Display Window accepts all of the standard X Toolkit command line options, which are documented in the OPTIONS section of the X(1X) refer- ence page. DESCRIPTION
The Display Window application, dxdw, can be used to run commands at specified time intervals. You can use Display Window to: Run a command and display a transcript of the output Repeat a command at regular intervals Print the output to the default printer Save the output to a file You can use Display Window to run common commands without starting up a full xterm. The optional -c option specifies an initial command. The Display Window application presents a transcript containing the current command, its output, and its command-line error messages. You can change the command after the application starts. The transcript area is output-only, so you cannot use Display Window to run commands that require user interaction on the command line. The Display Window application can be invoked from the CDE Application Manager from the following categories: Application Group: System_Admin System Admin Subgroup: Daily Admin When the Display Window main window invoked, the transcript is empty because there is no command running. Enter a command to run in the Command input text field. Because Display Window can be started with a default initial command, several launchpoints have been created in the Application Manager to run specific command-line applications. These applications include I/O Statistics (iostat), Network Statistics (netstat), Virtual Memory Statistics (vmstat), and Who? (who). To start one of the preceding applications within Display Window from the CDE desktop: Click on the Application Manager icon on the CDE front panel. Double click on the System_Admin application group icon. Double click on the Tools application group icon. Double click on the icon for the command you want to run in the Display Window application. The Display Window application invokes the command once. The output from the command is displayed in the transcript area. You can also start Display Window from the command line. To start Display Window from the command line, enter the following: /usr/bin/X11/dxdw [-c initial_command] The -c option specifies the command string to run when Display Window is started. On the command line, the command string must be enclosed in double quotes if it contains any spaces or special characters interpreted by the shell. The command string can be any of the following: A single command A series of commands in a pipeline (|) A series of commands separated by semicolons After Display Window starts, a new command string can be entered in the Command input text field. In the graphical user interface, it is not necessary to enclose the command string in double quotes. To enter a new command string: Clear the Command input text field if a command is already present. Enter a new command string in the Com- mand input text field. Press the Return key in the Command input text field to run the command. EXAMPLES
The following example runs the iostat command one time in the Display Window application. You can use the Repeat Every dialog box to repeat the command at regular intervals. dxdw -c iostat The following examples show how to use Display Window from the command line. dxdw -c df dxdw -c "ps -aef" dxdw -c "ps -aef | grep dxdw" dxdw -c "mount; showmount" You can view the Display Window online help volume without run- ning the application. To open the Display Window help volume from the command line, enter the following command: /usr/dt/bin/dthelpview -h /usr/dt/appconfig/help/C/Dxdw.sdl FILES
Contains the Display Window application executable Contains the Display Window help volume Contains the default values for the applica- tion's X resources SEE ALSO
Commands: iostat(1), netstat(1), vmstat(1), who(1), X(1X) dxdw(8)
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