Posts Tagged ‘FileSystem’

How-To Set Up a Continuos Synchronization on The Background With Windows 7 and The Group Policy Editor

Saturday, September 3rd, 2011

Using the Offline Files in Windows Vista or Windows 7 is not always a smooth process and can cause a lot of Offline Folders And Files Synchronization Errors.

Offline Files synchronization errors

Offline Files synchronization errors

I found the latest generation of Windows to be very sensitive in the process to keep synchronized the Offline Files and folders copy with the  remote share.

Depending on the quality of the network you rely or the quality of the link to the share the Windows 7 (or VISTA) clients may think that the share is temporarily unavailable and stop synchronizing the Offline Folder while leaving temporary files on the server.
That may confuse some applications, especially Microsoft Office making them believing that a file you just edited and closed is still opened by another application and will refuse to open such file again.

I.E.. I have a very unadvisable configuration where a Linux server is providing an NFS share to a Mac OS X Snow Leopard server, and that server is then re-sharing via SMB and AFP that share to Windows and Mac OS X clients. I have experienced problem with Windows Clients stopping to synchronize files without any reasonable motivation.

I understood that because of an obvious delay on the communication from the Windows client through the Mac OS X server (via SMB)  to the Linux server (via NFS) would make the Windows client believe that the share was offline with many unconfortable conseguences.

I have found a workaround to this problem playing a little with the Windows’s Group Policy Editor.

As I don’t have a Windows Domain in place I couldn’t generate a policy file to be pushed once for all to all the clients so I had to manually start and configure the Group Policy Editor on each single Window VISTA and Windows 7 machine.

This is how to set up a continuos synchronization on the background with the Local Group Policy Editor:

  1. Start the Local Group Policy Editor

    Launch The Local Group Policy Editor

    Launch The Local Group Policy Editor

  2. Expand the Computer Configuration policies to ‘Network -> Offline Files’
    Group Policy Editor

    Group Policy Editor

    Slow Link Speed

    Slow Link Speed

  3. Access the ‘Configure Backgraund Sync’ option to enable the background sync

    Configure Background Sync

    Configure Background Sync

  4. Activate the ‘Enable Transparent Caching’ option

    Enable Transparent Caching

    Enable Transparent Caching

  5. Access the ‘Configure slow-link mode’ option to enable the support for slow-link networks

    Slow Link Mode

    Slow Link Mode

  6. Access the ‘Configure slow-link speed’ to configure the latency level to detect weather the connection get slow.
    Follow the suggestions shown in the LGPE to calculate the appropriate value.

    Configure Slow Link Speed

    Configure Slow Link Speed

These settings should avoid many of your problems and so far they did not create any additional issue.

Please comment and post your experience about any problems with the use of Offline Files and Folders.

How the UNIX system Load Avarage is calculated on Mac OS X and Linux

Wednesday, August 24th, 2011

The Load Avarage values that are shown using the ‘top’ commad or the ‘uptime’ command represent the number of blocking processes in the run queue averaged over a certain time period.

An example fo HIGH Load Avarage:

 load average: 12.54, 12.71, 12.19

these values represent CPU, Disk I/O and Network I/O.

if you run the ‘top’ utility you can seek for the CPU usage and for the CPU I/O waiting time that are represented by the ‘us‘ and ‘wa‘ abbriaviations.

If these uage is permanently around 100% then chances are the problem is related to your CPU.

If the I/O waiting time is mostly above the 80% it means that there could be some problem with the I/O devices suche network cards or failing hard drives.

In my spefic case I notices that in ReadyNAS with 6 disks in RAIDX-2 the load avarage is constatly over 10.00,10.00,10.00. I believe this is normal considering that the ‘md’ process has to keep the RAID chain continuosly checksummed and alligned.

This information has been sources from Andy Millar’s really nice blog I have found digging around: http://www.andymillar.co.uk/blog/2006/12/24/linux-load-average-explained/

 

How-To set the Bundle attribute to a file in Mac OS X

Friday, September 10th, 2010

If you want to make a folder to appear like a Bundle File (a single transportable file) preventing the user to access a file (and possibly mess with its content) what you have to do is to set the Bundle attribute with this simple CLI command:

SetFile -a B <bundle file name>

You can use this technique if you want to restore the bundle attribute after a bundle-file (a directory container with bundle attribute) is transported through a bundle-incompatible file system like Linux and Windows file systems generally are.