关于rsync命令输出中total字段含义的技术咨询

Hey there, let's break down what that (total: X%) field actually means in your rsync output, since it's definitely not the overall task progress you initially thought.

核心含义：基于已发现文件数的动态比例 #

That percentage is tied to the number of files rsync has processed so far, relative to the total number of files it's discovered up to that point. The critical detail here is "discovered up to that point" — rsync doesn't scan your entire /volume5/Data/ directory upfront to get a fixed total file count. Instead, it traverses directories incrementally as it transfers files.

为什么百分比会上下跳动？ #

Here's the bounce logic in action:

• Suppose rsync starts and scans 100 files in the top-level directory. If it's processed 6 of them, you'll see (total: 6%).
• Then it dives into a subdirectory with 900 more files — suddenly the total discovered file count jumps to 1000. Now those same 6 processed files only make up 0.6% of the new total, so the percentage drops.
• As it keeps processing more files, the percentage will climb back up again as the number of handled files grows relative to the (now larger) discovered total.

结合你的输出细节来看 #

Looking at your full status line: (xfer=#279, to-check=1028/61716)

• 61716 = the current total number of files rsync has discovered so far
• to-check=1028 = the number of files left that rsync still needs to evaluate (whether they need transfer, skip due to --ignore-existing, etc.)
• xfer=#279 = the number of files that have actually been transferred

The total percentage is calculated as (number of processed files / total discovered files) — "processed" includes both transferred files and those it's skipped.

为什么它不是真正的总进度？ #

Rsync avoids showing a true overall task progress (based on total data size or total files) because pre-scanning the entire source directory would add massive overhead, especially for large, deep NAS shares. Rsync prioritizes starting transfers quickly instead of waiting to count every file and calculate total size upfront.

小建议：获取更准确的总进度 #

If you want a metric closer to the "total task progress" you're expecting, check if your Synology's rsync version supports the --info=progress2 flag. This option displays a progress bar based on the total number of bytes to transfer (once rsync has enough data to estimate it), which stabilizes after rsync has scanned enough of your directory structure.

备注：内容来源于stack exchange，提问作者Deekay