RAMdisk

RAMdisk installation

A RAMdisk is required to provide faster access to the FSY file which is used by TelliCast to buffer incoming data from the satellite as individual files are built up. As several files may be coming in at the same time, access to this file is very frequent, and unless the file lives on a fast disk, data can be lost. Using a RAMdisk removes any of the delay caused by the mechanical aspects of a hard disk (the movement of the arm to position the heads over the right track, and the rotation of the disk to place the data under the read-write heads).

Preferred RAMdisk

For Windows-7 and Windows-8, although the earlier AR Soft RAMdisk will install, however it does appear to be limited to 127 MB, and you cannot seem to share the resulting disk on the network. so an alternative is the free Dataram RAMDisk - Windows Vista, XP, Server from:

http://memory.dataram.com/products-and-services/software/ramdisk

Be sure to get the current version - I recommend Dataram_RAMDisk_V3.5.130RC9.msi or later. To change the disk letter requires that you create a disk image and save it, and configure the program to reload a disk image at startup. On my Test PC, I could configure a disk size of 250 MB, but the size wasn't quite what I expected allowing a file_database_size of only 261,000,000 (rounded) rather than near 262,144,000 bytes as you would expect. On a "180 MB" RAMdisk I could fit a 188,400,000-byte FSY file set. When sharing, use the Advanced option, add the user group "Everyone", and grant that group Full control. Note that a 300 MB RAMdisk is now recommended.

Documentation is installed in the program's directory as an HTML document.

Alternative: An even easier to use RAMdisk is the Gavotte RRAMdisk, described here:

http://www.jensscheffler.de/using-gavotte-ramdisk-in-windows-7

Note that it's supplied in 7-zip format, so may need an un-zipper such as: http://www.7-zip.org/ I preferred to remove the pop-up menu additions.

Uninstalling the AR-Soft RAMdisk: If you need to uninstall the earlier AR Soft RAMdisk - for example you need more than the 127 MB RAMdisk that software can provide - you can uninstall the program by running the AR Soft setup again, and selecting Uninstall. I'm afraid this escaped me until I asked on one of the groups!

As with most Vista and Windows-7/8 software, I have chosen to install outside the C:\Program Files\ tree, so I chose to install in: C:\Tools\RAMdisk\. On the first settings screen, choose the disk size as 180 MB, FAT16 partition, and Windows boot sector. When converted to bytes, and allowing a margin for the disk overheads, this requires a total FSY size around 188,000,000 bytes.

Please note that EUMETSAT are now recommending a 300 MB RAMdisk - making the total FSY size some 313,900,000 bytes. For MSG alone 60 MB is adequate, if including EPS (Metop) 500 MB is recommended in EUMETSAT's TD-15 PDF document, section 4.1.3.4.

Remember that 300 MB is now the recommended size. Once you have done that, you can start the RAMdisk with the Start RAMdisk button, and you should see a progress bar gradually filling, followed by a RAMDisk started successfully message.

At this point, it's possible to take an "image" or copy of the disk, which can be used to initialise the disk at startup. This step is required if you want to be sure of setting the disk letter consistently, and I recommend that you use the disk image. Click on Save Disk Image Now, and choose a location for the saved file.

I used the default file name, but put the file where I had installed the software: C:\Tools\RAMdisk\RAMDisk.img. Click OK.

There will be a short pause while the image is made.

Next, check the Load Disk Image at Startup box, and point the filename to the location where you have just saved the image.

Use the dialog to select the "image" file you just saved.

and press the Open button. Finally, you will be asked to confirm saving the new settings. Pres Yes if you are happy.

If you have changed settings, you will need to stop and restart the RAMdisk, so press OK.

[On a later Windows-7, 64-bit install of V3.5.130RC10 of the software, I found that there were slightly fewer prompts than were indicated above]

[Do check the disk letter, because one user reported that after using disk management to define the disk as drive Z:, they had to re-save the image because otherwise the next time it came up as H:. I haven't seen this myself.]

Changing the drive letter

Select the Administrative Tools, Computer Management option. If you are running on Vista or Windows-7 you may need to allow the program to run. These may not be on your start menu, but can be accessed through the Control panel. Double-click Disk Management. Highlight the drive letter which is currently assigned to the RAMdisk, and which you want to change. In this example, the RAMdisk had defaulted to drive G:.

Right-click the drive, and select the Change Drive Letter and Paths... option. Click the Change... button.

From the drop-down list, choose drive Z:

and click OK. You will get a warning, which you can dismiss with the Yes button.

Earlier AR Soft RAMdisk

The free AR Soft RAMdisk software (available to members of the MSG-1 self-help group) appears to function correctly under Windows Vista, provided that you tell Vista that the program is a Windows 2000 one. You do this with the following steps.

First, select the file, and right-click it. In the screen-shot below you will see I have named the file arsoft-ramdisk-setup.exe, as there are rather a large number of files named setup.exe! Select the Properties item from the pop-up menu.

Within the Properties dialog, select the Compatibility tab, and from the drop-down list select Windows 2000, and click on OK.

Once you have set the setup program's compatibility, you need to run it in Administrator mode. Right click the setup program, and select Run as Administrator.

The first screen is a standard Welcome screen. Press Next.

As usual, you need to accept the licence agreement. Please note that the free version available from the MSG-1 self-help group does not include support from AR Soft! Accept the agreement.

You wish to Install the RAMdisk, so be sure that the Install option is selected, and press Install.

Leave the Configure box checked, and press Finish.

Next, you must configure the RAMdisk to support EUMETCast. Change the Operating mode from RAM Disk mode to Emulate a local hard disk.

You need to size the RAMdisk according to the data you wish to take from EUMETCast. For the full MSG-1 data, FSD, EARS AVHRR, and the Metop-AVHRR data, and 80 MB RAMdisk is a good starting size. Use the slide control to select 80 MB. Yes, the slider is a little coarse, so use the left and right arrow keys to refine your value to just 80 MB, and the press OK.

The first time I got one of these dialogs - perhaps if I had used Windows 2000 compatibility the first time I would not have done?