Can qfs work with very slow interconnects?

[Ed Rainey]

Can qfs be configured to work with very slow interconnects?

By slow, I mean latency ~700 ms, jitter ~100 ms and bandwidth ~0.4 Mbps.

[Mehmet Can Kurt]

Hello,

Although we have never run QFS on a network as slow as you described, there is practically no reason for QFS not to work on such a network. You're going to have to adjust the timeout settings accordingly, since reads/writes will be slower and default timeout values are probably not suitable for the network you described. Please let us know if you need further guidance on the parameters that needs adjusting.

Note that you'll see some performance degradation compared to a faster network like with 10gigE interconnects. Low bandwidth will affect read/write performance since QFS's main goal is space efficiency rather than network efficieny, and it abandons data locality, e.g. max locality for reads with RS encoding is 1/6. Similar to reads/writes, chunk recovery on a chunkserver will be slower due to the need to fetch other chunks in the same chunk group. For the same reason, operations like chunk server evacuation should be also slower. Other than these apparent downsides, it is possible to configure QFS to make it work with your setting.

Best,

Mehmet

[Ed Rainey]

Thanks very much. Slow is good, sometimes.

Mehmet Can Kurt: