Hi there! Let's walk through your two key questions about backing up those vintage systems and creating a redundant copy with Macrium Reflect Free—great call getting ahead of potential drive failures, by the way!

关于将多个.mrimg文件打包为单个镜像的考量 #

First off, when you talk about creating a single image of External HDD #1 (which contains all those individual .mrimg files) onto External HDD #2, this is totally technically feasible with Macrium. That said, there are a few tradeoffs to keep in mind:

• Recovery flexibility: If you go this route, restoring a single computer's backup will require an extra step: you'll first need to restore the entire External HDD #1 image to a drive, then extract the specific .mrimg file you need. Compare that to just copying the .mrimg files directly to External HDD #2, where you can grab any individual image immediately for restoration. If you think you might need to restore just one system down the line, direct file copies are more flexible.
• Space and integrity: Making a full disk image does let you leverage Macrium's built-in integrity checks, which ensures the entire backup is intact. Just double-check that External HDD #2 has enough space to hold the used space of External HDD #1 (since you're imaging the drive, not the full 12TB if it's not filled up).
• Incremental vs. one-time: If you ever plan to add more backups to External HDD #1 later, a Macrium image lets you create incremental backups to update the copy on External HDD #2. But if this is a one-time redundant backup, direct file copies might be faster and simpler.

压缩设置的选择建议 #

Your concern about recompression is totally valid, but here's the good news: Macrium Reflect won't waste time trying to recompress your already-compressed .mrimg files. These files are already tightly packed, so the compression algorithm won't be able to shrink them further—instead, it'll just add unnecessary CPU overhead and slow down the backup process.

For this second backup step (copying External HDD #1 to External HDD #2), I'd strongly recommend choosing No Compression instead of the default setting:

• It'll speed up the backup significantly, especially with 12TB of data to process.
• You won't see any meaningful reduction in the final image size anyway, since the .mrimg files are already compressed.
• It reduces the chance of any compression-related glitches (rare, but possible with large datasets).

Also, quick note: updating to v8.0.7690 before you start is a smart move—newer versions often have stability fixes for large disk handling and image creation, which will help smooth out this big project.

备注：内容来源于stack exchange，提问作者Koenigsegg