Windows explorer over CIFS

  • Thread starter Thread starter byaarov
  • Start date Start date
B

byaarov

Hi,
When windows explorer goes to a directory mounted over CIFS, it loads
thumbnails for all the files in that directory.

Does it pull down each and every file and read all the contents of the
file to create the thumbnails every time someone visits a directory?

/B
 
Not each and every file, no. Explorer makes the API call for the
thumbnail, which of course is not the same as the full contents of the
file.

J Wolfgang Goerlich
 
Not each and every file, no. Explorer makes the API call for the
thumbnail, which of course is not the same as the full contents of the
file.

J Wolfgang Goerlich
Click to expand...

How does it generate a full view of the images in a folder with out
reading the entire contents of the file?

Thanks
B
 
The Windows server creates the thumbnails. Let's look at how to test
this out.

Create two folders, each with approximately 100 large (2-4 MB) JPEGs.
View the details but not the thumbnails.

Start Perfmon and remove all of the counters. Add the counter
PhysicalDisk: Disk Bytes/sec. Change the scale (under Properties >
Graph) to be from 0-10000. Open the first test folder and change the
view from details to thumbnails. You'll see a spike (its about 80-90
KBps on my box).

Change the view back to details and close the Explorer Window. Re-open
Explorer, point to the first test folder, and change the view to
thumbnails. Note that the disk Bytes/sec is relatively flat.

Add a second counter to the perfmon: Network Interface: Bytes Total/
sec.

Share out the second test folder. Open it from a Windows client,
viewing as details. Note the bytes that come off the disk and go over
the wire. It is very little at this point.

Now, from the Windows client, change the view to thumbnails. Watch
perfmon on the server. The bytes off the disk will be close to the
first test folder. The bytes across the wire will be relatively less.
Basically, all that is being sent over via CIFS is the thumbnail
image.

J Wolfgang Goerlich
 
The Windows server creates the thumbnails. Let's look at how to test
this out.

Create two folders, each with approximately 100 large (2-4 MB) JPEGs.
View the details but not the thumbnails.

Start Perfmon and remove all of the counters. Add the counter
PhysicalDisk: Disk Bytes/sec. Change the scale (under Properties >
Graph) to be from 0-10000. Open the first test folder and change the
view from details to thumbnails. You'll see a spike (its about 80-90
KBps on my box).

Change the view back to details and close the Explorer Window. Re-open
Explorer, point to the first test folder, and change the view to
thumbnails. Note that the disk Bytes/sec is relatively flat.

Add a second counter to the perfmon: Network Interface: Bytes Total/
sec.

Share out the second test folder. Open it from a Windows client,
viewing as details. Note the bytes that come off the disk and go over
the wire. It is very little at this point.

Now, from the Windows client, change the view to thumbnails. Watch
perfmon on the server. The bytes off the disk will be close to the
first test folder. The bytes across the wire will be relatively less.
Basically, all that is being sent over via CIFS is the thumbnail
image.

J Wolfgang Goerlich
Click to expand...

Interesting... how will this work if the file server is not windows
based... Lets say it were a NetApp or a Unix file server?

Thanks
B
 
Interesting... how will this work if the file server is not windows
based... Lets say it were a NetApp or a Unix file server?
Click to expand...

Hmmm ... not sure, never tried it. If I get some time over the
weekend, I will setup a Samba server and let you know. You could also
measure the network traffic from, say, the Windows client and see.

J Wolfgang Goerlich
 
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