On Wed, 27 Jan 2016, Mini Trader wrote:
Slow CIFS Writes when using Moca 2.0 Adapter.I am experiencing this only under OmniOS. I do not see this in Windows or Linux. I have a ZFS CIFS share setup which can easily do writes that would saturate a 1GBe connection. My problem appears to be related somehow to the interaction between OmniOS and ECB6200 Moca 2.0 adapters. 1. If I write to my OmniOS CIFS share using ethernet my speeds up/down are around 110 mb/sec - good 2. If I write to my share using the same source but over the adapter my speeds are around 35mb/sec - problem
MoCA has a 3.0+ millisecond latency (I typically see 3.5ms when using ping). This latency is fairly large compared with typical hard drive latencies and vastly higher than Ethernet. There is nothing which can be done about this latency.
Unbonded MoCA 2.0 throughput for streaming data is typically 500Mbit/second, and bonded (two channels) MoCA 2.0 doubles that (the claimed specs are of course higher than this and higher speeds can be measured under ideal conditions). This means that typical MoCA 2.0 (not bonded) achieves a bit less than half of what gigabit Ethernet achieves when streaming data over TCP.
3. If I read from the share using the same device over the adapter my speeds are around 110mb/sec - good
Reading is normally more of a streaming operation so the TCP will stream rather well.
4. If I setup a share on a Windows machine and write to it from the same source using the adapter the speeds are around 110mb/sec. The Windows machine is actually a VM whos disks are backed by a ZFS NFS share on the same machine
This seems rather good. Quite a lot depends on what the server side does. If it commits each write to disk before accepting more, then the write speed would suffer.
So basically the issue only takes place when writing to the OmniOS CIFS share using the adapter, if the adapter is not used than the write speed is perfect.
If the MoCA adaptor supports bonded mode, then it is useful to know that usually bonded mode needs to be enabled. Is it possible that the Windows driver is enabling bonded mode but the OmniOS driver does not?
Try running a TCP streaming benchmark (program to program) to see what the peak network throughput is in each case.
Any ideas why/how a Moca 2.0 adapter which is just designed to convert an ethernet signal to a coax and back to ethernet would cause issues with writes on OmniOS when the exact same share has no issues when using an actual ethernet connection? More importantly, why is this happening with OmniOS CIFS and not anything else?
Latency, synchronous writes, and possibly bonding not enabled. Also, OmniOS r151016 or later is need to get the latest CIFS implementation (based on Nexenta changes), which has been reported on this list to be quite a lot faster than the older one.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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