5 port netgear switch suggestion for setting up teaming/LAG on Readynas nvx

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HomeNASUser2020 wrote:

i was thinking of using the second network port on the NVX to setup teaming (LAG) but the more I read about this it seems like it will not improve perform in any way for my 4 totals users. Is this the case or is will it provide some other advantages and if so what are they?

 

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The short story here is that while LAGs can sometimes boost throughput, they don't always do that - and they can sometimes create problems.  Normally they work best when there are a lot of simultaneous users (with four users total, your gains would likely be marginal).  But I don't think you'll see any gain with an NVX (more on that below).

In order to get any advantage you'd need to have to extend the 2 gigabit connection from the NAS to the switch or router that the users are connected to.  Otherwise you'll still end up with a 1 gigabit limit (bottlenecked by the link between the switches).  So connecting the NAS to its own 5 port switch with LAG won't accomplish anything.  Even if the NAS and the users were connected to the same switch, you could only see gain if 2 or more users were using the NAS simultaneously - since each user's link speed would be at most 1 gigabit.

More fundamentally, you can only see performance gain when the throughput is limited by the network speed. Although I've never owned an NVX, based on some old reviews, the performance of the NVX is already below the 1 gigabit link speed - and is about 75 MB/sec, (or 600 megabits ).  If that's correct, then you won't see any performance gain with LAG, since the speed isn't limited by the network.  You can test your single-user speed with NAStester ( http://www.808.dk/?code-csharp-nas-performance ).

If the review speeds are correct, then the best approach to increasing throughput would be to get a new NAS (for instance an RN42x or RN52x) - that would give you about a 25% speed boost for large file transfers - without LAG.  

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HomeNASUser2020 wrote:

 

Also can you please explain why i would need more port on the switch if i wanted to setup LACP

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It's simple - Netgear doesn't make a 5 port switch that supports LACP.  The GS108T is an 8-port switch that would work.

Note you could try TLB or ALB with your existing switch or router.  TLB only increases speed in the NAS->user direction (read speeds), ALB can increase speed in both directions.  These methods sometimes misbehave - but if you have problems connecting to the NAS or transfering data, you could just turn them the LAG again and disconnect the ethernet cable.

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HomeNASUser2020 wrote:

what are the benefits of doing this over your other suggestion of (setting up a static LAG on the switch, and using Round-Robin on the NAS)?

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LACP is dynamic - so if a cable is removed or a switch port fails, it will automatically drop that connection from the LAG.  With two ports, that means it would drop back to a single connection.  It's also negotiated when the connection(s) are established, which can make it a bit easier to set up.

One other difference with LACP is that the data flowing to any specific user goes over only one of the two network connections.  That ensures that the end-to-end dataflow for each user stays below 1 gigabit, and that the packets always arrive in order.  FWIW, that's not always an advantage.  With only two users, there is a 50-50 chance that they will both share the same NIC on the NAS - so there is only a 50-50 chance of seeing a performance boost.  This would be persistant btw - those two users would always use the same connection path.

Round-robin alternates packets across the two connections, so it will always use both links.  That eliminates the 50-50 chance possibility, but it creates a different problem - the NAS will try to deliver more data to the client than it can receive.  That will create packet loss, which can sometimes result in a performance drop due to retransmission instead of a performance gain.  You can use ethernet flow control to eliminate this possibility - though the normal TCP flow control ought to handles it in most cases.

Another aspect is that the round-robin only applies to packets being sent by the NAS.  The switch decides what packets to put on what link in the other direction.  If the switch uses the same approach taken by LACP, you would have the same 50-50 chance of seeing no speed boost with two users in the switch->NAS direction (e.g., write speeds might not improve).