Introduction to Ramdisk Boot Mode
Introduction to Ramdisk Boot Mode
Ramdisk is a virtual disk technology. Almost all of our PE systems boot from a computer using the ramdisk method. So, what are the characteristics of ramdisk?
Ramdisk Virtualizes Memory as a Disk
Ramdisk technology virtualizes a portion of your memory into a disk partition. When booting a PE system from a USB drive and opening the file explorer in the PE system, you’ll see that the system drive of the PE is a partition of several GB (likely the X: drive). This is the virtual disk created by Ramdisk.
If your computer has 16GB of RAM, after Ramdisk virtualizes 8GB as the PE system drive, it would seem that only 8GB of actual memory remains.
However, something doesn’t add up! We only allocated 2GB of memory to our virtual machine, yet this 8GB…
RAMDisk may utilize virtual memory technology to expand the size of the RAMDisk system disk. This allows it to simulate a larger disk space without actually occupying real physical memory.
The system files of the PE system are only temporarily extracted into the Ramdisk virtual disk. Therefore, even if all other disks on your computer are damaged, as long as the memory is functioning normally, Ramdisk technology will successfully virtualize a disk for the PE system to use.
Where are the system files of the PE system? In fact, the system files of WePE are packaged in a WIM file. This WIM file is located inside the WePE ISO file.
So, in reality, you can copy this WIM file out separately and configure it appropriately to boot the PE system without burning the ISO onto a USB drive.
Ramdisk technology can, to some extent, prevent viruses from running in the PE system, since running a virus in a memory-virtualized disk is not an easy task.
The Future of Ramdisk
In modern times, extremely high-end computers can be equipped with 512GB or even 1TB of memory. In such cases, using Ramdisk to boot a Windows 10 computer offers the following advantages:
1. Prevents system corruption: Since memory is a volatile storage medium—meaning all data in memory disappears when power is lost—this ensures the system cannot be damaged. After shutdown, the virtual disk disappears, and the system files from the WIM package are re-extracted into the Ramdisk disk each time the computer starts. Every boot returns the system to the state backed up in the WIM package. Thus, system corruption is prevented. However, this also means that all user changes are lost after shutdown, and any new files saved in the Ramdisk are completely erased. So, one inconvenience is the need to back up files before shutting down.
2. Significantly improves system speed: Since the system drive in Ramdisk mode is essentially memory, its read speed is extremely fast. Memory read/write speeds are 10 to 1000 times faster than hard drives. Therefore, system responsiveness can reach its peak.
**However, for ordinary computers, using ramdisk technology to boot a full Windows system is impractical. **Because we’re poor :)
Using ramdisk to boot a PE system, however, is a great choice.
Booting a PE System in Ramdisk Mode
First, why do we need to use this special ramdisk mode to boot a PE system? In what scenarios do we use ramdisk to boot a PE system?
As a computer repair tool, the PE system needs strong adaptability to ensure it can run on any computer.
A computer can lack a hard drive, but it cannot lack a memory module. So, if the computer’s hard drive is damaged, ramdisk technology can still use the memory-virtualized system drive to run the PE system. This is one reason we use ramdisk.
In what scenarios do we use ramdisk to boot a PE system? The bootable USB drive (bootable USB stick) created with the WePE Toolbox uses ramdisk to boot.
So, how can we use existing tools, such as our own computer (or virtual machine), to boot directly into WePE without inserting an external USB drive?
In other words, how do we manually install a PE system into our own computer?
First, the materials we need are: the WePE system ISO disc image file and the BOOTICE software. (This tutorial uses a virtual machine as a demonstration.)
Select a virtual machine that already has a Windows system installed, start this virtual machine, extract the WIM package from the WePE ISO, and place it into the virtual machine’s disk.
Steps:
1. Add the WePE ISO to the virtual machine.
2. Open the WEPE folder; the file WEPE64.WIM is the WePE WIM package.
3. Copy WEPE64.WIM into the virtual machine’s disk (any location is fine).
Now that the WePE WIM package is ready, the next step is to boot the WePE package using ramdisk.
Ramdisk, as a low-level feature, does not require installing additional software; you only need to properly edit the BCD menu to boot the WIM.
Since we need to edit the BCD file, we must use the small tool BOOTICE.
Steps:
1. Open BOOTICE, select BCD Edit -> Smart Edit Mode.
2. Click Add -> New WIM Boot Entry.
3. Device Type: Ramdisk, Boot Disk: The disk where the copied WIM package is located. Boot Partition: The partition where the copied WIM package is located.
4. Device File: Enter the path to the copied WIM package. Remember to add a backslash \ at the beginning.
5. SDI File:
Oh, I forgot to mention earlier: the SDI file is specifically used to virtualize memory into a virtual disk. The system drive we see in the PE system is actually virtualized by this file. Therefore, the SDI file is indispensable in ramdisk mode.
Where is the SDI file? It’s still in the WePE ISO, in the same folder as WEPE64.WIM. Its name is WEPE.SDI.
You can place this SDI file anywhere on the VM’s virtual disk, such as the C: drive, D: drive, or even the hidden EFI partition (though that would be troublesome and unnecessary).
Continuing:
5. SDI File: Click on [boot] on the left, select the location of the SDI file. For example, if I placed it in the root directory of the D: drive, I would select the D: drive, using the same method as selecting the WIM package.
6. Enter the SDI file path. I should enter \WEPE.SDI (don’t forget the backslash).
7. Menu Title: Feel free to choose any name.
8. Check the option Boot to WinPE at the bottom, since we are booting a PE system.
9. Save Current System Settings -> Save Global Settings.
Now, we have successfully configured the WePE boot menu entry in the virtual machine, set to boot in ramdisk mode. We can restart and test whether it works.
We can use this method to add WePE to our own computer for easy maintenance.