During a mixing session
This is a handy tip-sheet to have open when launching a session. I close the web browser once everything is running because… performance.
Assign a unique remotename (“-K”) parameter to each player (choosing a name between “Player1” and “Player[n]” depending on the number of people you’re hosting. That’s how the “connect_players” command drops people into the mixer.
Start Jacktrip Server -- Minimum jacktrip -S --hubpatch 5 Launchers for Jacktrip 1.3 and 1.4 are on the desktop (the "Basic Mixer" ones) Start Jacktrip Server -- w/Broadcast option jacktrip -S --hubpatch 5 --broadcast 50 Use the Jacktrip 1.4 launcher and select the Broadcast option in the user interface Players -- Minimum command line jacktrip -C [server IP address] -K Player[n] Connect the players to the session Use the "Connect players" launchers on the desktop. The loopers are the ones I prefer Get Linode-server performance statistics Launch the Task Manager from the desktop
What size Linode?
The mixers will run in the Minimum configuration — great for development, testing, experimenting and so forth. The larger templates will run out of memory on the Nanode — I run them in larger machines. I use “Shared CPU” not “Dedicated CPU” Linodes because they work fine and … Cheap Is Good.
The Pretty Good is… pretty good! I might go up a bit if the performance was really important. I’d like to get more experience in how reliable the smaller sizes are.
Here are the tiers, based on Linode pricing for Shared-CPU virtual servers when I wrote this page. Use it as a guess, not a guide. 🙂
Template Plan RAM CPUs Storage Monthly Max Hourly mb/sec 5-Player Minimum Nanode 1GB 1 25 GB $5 $0.0075 15 Pretty good Linode 4 GB 4GB 2 80 GB $20 $0.03 10-Player Minimum Nanode 1GB 1 25 GB $5 $0.0075 30 Pretty good Linode 8 GB 8GB 4 160GB $40 $0.06 15-Player Minimum Linode 2 GB 2GB 1 50 GB $10 $0.015 45 Pretty good Linode 8 GB 8GB 4 160GB $40 $0.06 20-Player Minimum Linode 4 GB 4GB 2 80 GB $20 $0.03 60 Pretty good Linode 16GB 8GB 6 320GB $80 $0.12
The last column in that table is “mbits/sec” and refers to the speed that the template will write data to the disk if all the players are being recorded at their defaults (48k sample rate, 16-bit, stereo). The more players, the more disk-writing bandwidth is required of the server. Each player uses 3 mbits/s
There’s a trick. Linodes vary widely in how fast they write data to disks. Here is a test session that is attempting to record to a disk that can’t keep up. This is a 20-track, 40-channel recording and thus it needs to be able to write to disk at about 60 mBits/second. This particular Linode was writing to disk at about 20 MBytes/second, which should be enough to keep up but wasn’t. The funny “gremlin” sounds are the result.
I have started “tasting” servers that I plan to use for recordings. I do this with a command-line string that, misconfigured, can destroy the data on the disk. I only use it on “fresh” servers that I’ve just built. That way, I’ve lost nothing if damage occurs. Backups are a good thing if you’re testing a disk with valuable information.
Here’s the string:
dd if=/dev/zero of=/tmp/test2.img bs=1G count=1 oflag=dsync
Click here for documentation (and more warnings). Here are the results from a Linode 4 GB that I use for development.
1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 95.5291 s, 11.2 MB/s
The most important thing to look at is the 11.2 MBytes/s disk-write speed. That’s Pretty Good for smaller sessions, but may fall short for larger ones. Note the difference between mbits/second in the table, and MBytes/second in the test result — about 8 times larger.