Queue downloads and only load 1 file at a time. Ideal for sequential reading of files on HDD on NAS.

[porg]

Use case: On your NAS trigger multiple downloads (certain remote source files to certain local destination folders) and then let them download unsupervised most efficiently

Source: NAS with HDD serving these files (e.g. movie recordings from a wedding) via e.g. SFTP or SMB, accessed with Cyberduck

1.mov 2.mov 3.mov 4.mov 5.mov 6.mov 7.mov 8.mov 9.mov

Target 1: USB drive on my Mac of auntie Anna

chatting/    dancing/   kids/   show/   speeches/  

Target 2: USB drive on my Mac of uncle Charles, attached at the same time

familyDoe/    familyDane/

User goals

• I initiate the file operations quite quickly — I achieve to queue all my desired downloads in 2min
  • 6 files into 3 different folders on auntie Anna's USB
  • 7 files into 2 folders that are sufficient for uncle Charles filing needs on his USB drive
  • I am only limited by the speed of my mind and my dexterity with drag and drop operations
• I leave the download unattended for the rest — This may take 60min, I don't mind
• I want that to happen as fast and efficient as possible.

General

• When you perform your file drag and drop operations from the Cyberduck window to the local file browser window (e.g macOS Finder) Cyberduck creates a list of file transfers.
• Cyberduck → Settings → Transfer: Controls how such a transfer list is processed.

Settings needed for use case: Do not exist in Cyberduck currently

Environment: Cyberduck 9.1.2 on macOS 15.2 Sequoia

Desired settings for use case: Download 1 file at a time.

• This is ideal when files 1, 2, 3 come from the same NAS from the same HDD.
• Because then each file can be read sequentially.

Current situation

• Whereas if 1, 2, 3 download in parallel (as it happens now) the disk heads have to constantly move between the current chunk of 1, then current chunk of 2, then current chunk of 3, within their time-slot or fill-next-buffer based multiplexing algorithm which facilitates the parallel download over the single network link.
• This parallel downloading does not utilize the strengths of the HDD (sequential reading) but instead suffers from its weakness (random access). It takes far longer in total.
• Also on a protocol level the parallelization is only an overhead, not a gain, for this particular LAN scenario.

Workaround: Not really

• I can initiate /NAS/wedding/1.mov → /Anna-USB-Drive/dancing/1.mov
  • Then let it run alone. Come back.
  • Trigger next transfer.
  • And so on.
• Highly inefficient and cumbersome.

[dkocher]

Detailed report ❤️ . What you are looking for is supposedly

• Limit the number of concurrent transfers and connections per transfer
• May want to disable segmented downloads as this causes disk I/O when concatenating the segments

[dkocher]

Relates to #16433.

[porg]

Before I filed my issue, I ofc conducted research:

• and also came across Segmented download I/O #16433 which is about parallel write access on the client side.
• But this issue is about achieving sequential access on the server side by consciously choosing to transfer sequentially.

Turns out that how to set the max. number of downloads and also bandwidth control in Cyberduck as of v9.1.2 suffers from a lack of discoverability! I realized that after I read your linked documentation and not finding what it describes in the current UI. See my analysis of the usability issues and my recommendations how to fix and improve them.

1) UI rendering glitches in the transfer windows

The dropdowns for max bandwidth and max parallel connections are totally mutilated (icon cut off, no numbers like "1 MB/s" near bandwicth or "3" near connections), therefore I never discovered the function there!

2) No redundant/alternative presence in the Settings

Where I suspected it, my recommendation, add a hint about bandwidth / connection control to the Settings → Transfer, b/c there users can realistically expect it too.

2b) On the Mac: Main Menu → Help → Search

• Would be another way for discovering features.
• Currently bandwidth / connection control is not exposed there at all. Another possibility too.
  • Extra plus: Shortcut access + native customization (via System Settings → Keyboard → Shortcuts → Application Shortcuts)

3) "Browser Connection" mode

Currently has no bandwidth/connection control at all

• It uses max bandwidth and auto-connections, proven by this observation:
• If you start a second transfer, the transfer stats on the bottom flicker between the stats of transfer 1 and 2 constantly.

Could integrate bandwidth and connection limit control too (if you want that conceptually)

• This mode is different enough from the modes with the transfer window which serves all windows.
• So it would certainly benefit if it could have its own real bandwidth/connection control too.
• But if not, users have this "good enough" workaround: Open a single browser window only and use the Transfer Window for bandwidth/connection control.