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Thursday 11 February 2010

Tuesday 9 February 2010

Noatime and atime attribute on Linux

Linux records information about when files were created and last modified as well as when it was last accessed. There is a cost associated with recording the last access time. The ext2 file system of Linux has an attribute that allows the super-user to mark individual files such that their last access time is not recorded. This may lead to significant performance improvements on often accessed frequently changing files such as the contents of the /var/spool/news directory. 
Linux has a special mount option for file systems called noatime that can be added to each line that addresses one file system in the /etc/fstab file.
If a file system has been mounted with this option, reading accesses to the file system will no longer result in an update to the atime information associated with the file like we have explained above.
The importance of the noatime setting is that it eliminates the need by the system to make writes to the file system for files which are simply being read.
Since writes can be somewhat expensive, this can result in measurable performance gains. Note that the write time information to a file will continue to be updated anytime the file is written to.
In our example below, we will set the noatime option to our /chroot file system. 

Edit the fstab file vi /etc/fstab and add in the line that refer to /chrootfile system the noatime option after the defaults option as show below:

/dev/sda7          /chroot          ext2          defaults,noatime          1  2
         
You need not reboot your system for the change to take effect, just make the Linux system aware about the modification you have made to the /etc/fstab file. This can be accomplished with the following commands:            

/#mount -oremount /chroot/

 

Monday 8 February 2010

Using Winaudit to audit PC's to SQL Database

  • Download the Winaudit application from http://www.pxserver.com/WinAudit.htm
  • Setup a SQL DB for audits
  • Create a windows user who has 'write' rights
  • copy winaudit folder and application into root of c drive
  • create odbc connect (on pc to be audited) to sql db using designated windows user
  • create winaudit script and schedule as follows and save to root winaudit folder, then schedule auto-run  of this script
winaudit /r=report /o=ODBC /f=ODBC connector name /u=user /p=password
r=gsoPxuTUeERNtnzDaIbMpmidcSArCHGBLJF
Server: SQL Server name
DB: Database Name

    Friday 5 February 2010

    Changing WIndows NIC binding order - Win Serv 2008


    If an additional NIC is added to a Windows server the binding order will change. This may stop services like Documentum from functioning. To change the Adapter order in Windows Server 2008:
    Control Panel
    Network and Sharing Center
    (left hand pane) – Manage Network Connections
    (on toolbar for window) Advanced > Advanced Settings
    On the Adapters and Bindings Tab the order of the NIC’s can be changed. Make any data IP NIC’s top of the list, iSCSI and others further down the list

    Tuesday 2 February 2010

    Gobbler's Knob

    Bad news from Gobbler's Knob. Punxsutawney Phil saw his shadow so it's six more weeks of winter...


    Linux - split and rejoin large files

    In Linux it is possible to split big files, say ISO's into smaller, user defined chunks. For example, to split a 5Gb ISO into 250Mb chunks, open a bash terminal and type:


    split -b250m filename.ISO iso-split


    When run the filename>ISO file is split into 250 MegaByte chunks and iso-split is prefix of generated file(s).
    To restore the file(s) back into one chunk type:


    cat iso-split* > NEWFILENAME 


    If you need to rejoin the file in windows then go to a command prompt and type:


    type filepart1 filepart2 > filefull


    Where filepart1, 2 etc are the chunks made by the linux split command