I just checked a bunch of tests and found that it cannot handle using tcp connection using syslog-ng.
Here are my test results for those who want to try. I used the loggen program for this and sent 200-byte messages to the tcp port assigned to me by loggly. Please note that although syslog RFC (at least 3164) indicates that the log message should not exceed 1024 bytes, I used 200 byte packets just to be fair and because many messages are so small.
Signed up for a free account. Configured TCP connection for testing. Tried to send various amounts, results:
Test 1: FAIL
loggen -iS -r 6000 -s 200 -I 100 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 1392.13 msg/sec, count=18296, time=13.142, (average) msg size=200, bandwidth=271.74 kB/sec
Test 2: FAIL
loggen -iS -r 4000 -s 200 -I 100 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 2767.16 msg/sec, count=121146, time=43.779, (average) msg size=200, bandwidth=540.15 kB/sec
Test 3: FAIL
loggen -iS -r 2500 -s 200 -I 100 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 1931.27 msg/sec, count=85878, time=44.467, (average) msg size=200, bandwidth=376.98 kB/sec
Test 4: FAIL
loggen -iS -r 2000 -s 200 -I 100 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 1617.72 msg/sec, count=83134, time=51.389, (average) msg size=200, bandwidth=315.78 kB/sec
Test 5: FAIL
loggen -iS -r 1000 -s 200 -I 100 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 936.50 msg/sec, count=63331, time=67.624, (average) msg size=200, bandwidth=182.81 kB/sec
Test 6: PASS for duration, FAIL> 100 seconds - SEE TEST 7
loggen -iS -r 500 -s 200 -I 100 logs.loggly.com 16225 average rate = 325.00 msg/sec, count=32501, time=100.001, (average) msg size=200, bandwidth=63.44 kB/sec
Test 7: FAIL - earned a new test @ 500 EPS for a longer period, and the pipe broke after 255 seconds:
loggen -iS -r 500 -s 200 -I 10000 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 323.35 msg/sec, count=82642, time=255.577, (average) msg size=200, bandwidth=63.12 kB/sec
Test 8: FAIL (lasting more than 200 EPS, but still failed)
loggen -iS -r 200 -s 200 -I 10000 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 163.53 msg/sec, count=234090, time=1431.470, (average) msg size=200, bandwidth=31.92 kB/sec
Test 9: FAIL (again, lasted longer, but still failed)
loggen -iS -r 50 -s 200 -I 10000 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 47.36 msg/sec, count=89325, time=1886.014, (average) msg size=200, bandwidth=9.25 kB/sec
Test 10: FAIL? (same results but lost connection again. Is it hard to believe that they cannot handle 10 eps?)
loggen -iS -r 10 -s 200 -I 10000 logs.loggly.com 16225 Send error Broken pipe, results may be skewed. average rate = 9.94 msg/sec, count=1568, time=157.770, (average) msg size=200, bandwidth=1.94 kB/sec
Was there some kind of web search to see what loggly can do, but theres only marketing material that says it is scalable and not how scalable it is. I found this: http://twitter.com/jordansissel/status/5948244626509824 This is a total of 22 events per second ...
Full disclosure: I am the founder of LogZilla, so I tested the competition because we are running the syslog cloud solution. My tests show that our software can handle 2,000 to 12,000 events per second, depending on which servers we use in the cloud.