The RAM Disk instructions state that saving its contents to the SSD is possible (via using image file).
I use the program in the following way:
I reserve 10 GB for my RAM disk. After running a certain software, its output is saved to my RAM disk. The computer performs this operation very quickly and the results take up a few hundred MB.
I create an image of these, which is transferred to my SSD. However, that image takes up 10 GB, not just a few hundred MB (?). For me, this means that the disk saves all its 10 GB, including empty RAM cells.
I guess that in practice it may be only a reservation of this memory area. So I want to know, will I have 10 GB written to my disk every day, despite the actual use of only several hundred MB? If that were the case, I would have to give up the image of these files and just copy them directly to the SSD drive on an ongoing basis.
Is my reasoning correct?
Regards
Artur
The true size of RAM disk image file
Started by Artur
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Re: The true size of RAM disk image file 12 June 2025, 10:57 |
When using a RAM disk with an attached image file, it is important to understand the difference between the logical size of the image and the actual disk space it occupies.
By default, RAM disk image files are created as sparse files, which means they consist mostly of zeroed-out space and initially take up very little actual space on the SSD. For example, a newly created 10 GB image file may show a size of 10 GB but actually occupy only a few hundred kilobytes on the physical disk, as shown below. This usage will grow only as you write more data to it, and will typically reflect the actual amount of data stored, not the full designated image size.
Additionally, if you are using a persistent RAM disk (where the contents are loaded from the SSD on startup and saved back on shutdown), the saving process uses differential writing. That means only the parts of the image that have changed are written back. For instance, if you have 100 files of 2 MB each and only one file has changed, only ~2 MB will be written back to your SSD during shutdown (not the full 10 GB), thus protecting your SSD from unnecessary write operations.
So no, your SSD will not be written with the full 10 GB every time. Only the actual data used and changed will be saved. Your current approach should indeed reduce wear on the SSD.
By default, RAM disk image files are created as sparse files, which means they consist mostly of zeroed-out space and initially take up very little actual space on the SSD. For example, a newly created 10 GB image file may show a size of 10 GB but actually occupy only a few hundred kilobytes on the physical disk, as shown below. This usage will grow only as you write more data to it, and will typically reflect the actual amount of data stored, not the full designated image size.
Additionally, if you are using a persistent RAM disk (where the contents are loaded from the SSD on startup and saved back on shutdown), the saving process uses differential writing. That means only the parts of the image that have changed are written back. For instance, if you have 100 files of 2 MB each and only one file has changed, only ~2 MB will be written back to your SSD during shutdown (not the full 10 GB), thus protecting your SSD from unnecessary write operations.
So no, your SSD will not be written with the full 10 GB every time. Only the actual data used and changed will be saved. Your current approach should indeed reduce wear on the SSD.