[tahoe-dev] Performance question: reading from/writing to a grid of 4 data centers using 9-out-of-24 coding

[Robin Chen]

Hi,

I have recently started my experiments with Tahoe and deployed 24 Tahoe
storage nodes in 4 data centers (using 9 out-of 24 coding), but I'm running
into a performance problem.

I'm new to this email list, so I'm not sure if this problem has been
discussed before or not.

I would expect the "reading" performance (reading 9 shares) to be better
than the "writing" performance (writing 24 shares in 4
geographically-distribute data centers), but the reading time is typically
two times longer in most of my tests with files > 300MB.

For example, for a file size of 383MB,  I'm getting about 16Mbps in
throughput for writing, but only about 8.8Mbps in reading.

Any possible explanation?

Thanks!

Robin
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