FAQ Why so few peers and slots? Can I raise them?

[Silas Mariusz]

Symptoms

• A torrent holds fewer peers than the tracker reports.
• Only some of the connected peers send or receive data at the same time.

Cause
Each torrent runs on the Public or the Private connection profile, chosen by the private flag in the .torrent file. Each profile sets how many peers a torrent holds, how many it uploads to and downloads from at once (its slots), and how many peers it asks each tracker for.

By default a public torrent holds 40 to 200 peers with 30 upload and 30 download slots, and asks each tracker for 100. A private one holds 20 to 100 peers with 15 upload and 100 download slots, and asks for 50. All torrents together have at most 150 upload and 100 download slots.

A slot is not a peer: it is a peer that may transfer data at this moment. These numbers are limits, not a promise. A small swarm gives you few peers whatever the maximum.


Resolution

1. See what rtorrent runs. On the Dashboard, the Peers and their limits card shows the connected peers, the busiest torrent and rtorrent sockets: … of …. Turn on Advanced at the top of the page to see every value in the columns Now, Set and Default.
   
   
2. Pick the profile for your line. Open Settings → Connection profiles and press 1 Gbps, 2.5 Gbps or 10 Gbps. The confirmation lists the old and new value for every change. Press Apply. The same choice is in the link profile chip of the Peers and their limits card.
   
   
3. Or set the numbers yourself. In Settings → Connection profiles, press Custom…. Change min and max in the Public profile: peers per torrent row, upload and download in the Public profile: slots per torrent row, and Public: peers each tracker is asked for. The Private profile has the same fields. Press Review & save and confirm the changes in the window that opens. rtorrent applies them without a restart.
4. The totals for all torrents are in the Global slots row of Settings → Bandwidth & limits, with Advanced on.

Notice & Advise

• A link profile also sets the piece cache and both speed limits for a line of that speed. On a line with a slower upload, check the upload limit after you apply a profile.
• More peers do not always mean more speed. Every connection costs the NAS processor time, memory and buffers, and a router has to handle every one of them. A few fast peers often transfer more than hundreds of slow ones.

Ref. links:
Rtorrent 16 guide: Public and private connection profiles