Am I getting really rubbish performance out of my switches ?

[mikkydoos]

If I use LANSpeedtest against a network share I'm only getting 700mbps write and 350mbsp read. Thats 85 MB/s ish on the write.

 

All switches are gigabit Cisco's going down shortish lengths (<50m) of CAT5e. All server NICs are at least duals mostly quads. Cient NICs are all gigabit.

 

 

Why is it so slow ?

[Michael]

That's probably about right for your average SATA 300 disk. If you installed SATA SSDs or indeed SATA 600 disks (if supported by the controller), then this of course improves further.

 

Remember Gigabit itself is capable of 120MB/s - teaming will of course increase this, but that doesn't automatically mean 240MB/s as the disks in your servers (with everything else going on), will only process so much.

 

It goes to show that deploying Gigabit to the desktop does work and that 12MB/s on 10/100 just isn't enough these days!

[mikkydoos]

Yeah you're right but I'm losing a lot on quad NIC's to quad NIC's over 1gb fibre. I think it should be nearer 1000 Mbps. Might test it on Linux machines. Probably will be better results

[mdench]

Your most likely being limited by the speed at which the disks in your servers can be written to. So your network may support 1000Mb/s doesn't mean your disks can do the same

[Michael]

Drivers do play a huge role, but presumably you have trunk ports configured on your switches to use the Quad NIC to the max? I guess the alternative/easier option would be a single 10Gbps adapter. You probably lose less overhead overall.

[ChrisH]

When they are teamed they don't generally use all the channels at once, it's more like an overflow/redundancy system where they will only utilise the other(s) when there is a need.

[Michael]

Well thinking about it - teaming gives you 4000Mbps in each direction, which equals 480MB/s theoretical max. This is well beyond what a typical SATA drive can cope with. SSDs or SAS drives are needed to use this kind of bandwidth to the max.

[tmcd35]

Well thinking about it - teaming gives you 4000Mbps in each direction, which equals 480MB/s theoretical max. This is well beyond what a typical SATA drive can cope with. SSDs or SAS drives are needed to use this kind of bandwidth to the max.

 

My understanding of teaming is - it doesn't quiet work that way. A single stream would only use 1000Mbps. However 4 streams can each transmit at 1000Mbps in parallel to give you the theoretical maximum 4000mbps, rather than transmitting in series as they would on a single 1000Mbps link.

 

I know it's not that simple either - since data is transmitted in much smaller packet sizes, and an element of packet management enters in. But, AFAIK, on bonded links the maximum transmission speed between two devices would still be 1000Mbps not 4000Mbps.

 

Unless I've misunderstood something...

[Michael]

I was under the impression if you trunked or properly 'teamed' the quad adapter, it would give you the equivalent of 8Gbps. As for how much your hard drive will read/write is a separate issue, however it would give close to 10Gbps for a fraction of the price.

[Soulfish]

I was under the impression if you trunked or properly 'teamed' the quad adapter, it would give you the equivalent of 8Gbps. As for how much your hard drive will read/write is a separate issue, however it would give close to 10Gbps for a fraction of the price.

 

Not quite. Think of it a bit like a motorway vs a single lane road. If we assume both have the same speed limit, then for a single car it's going to take the same time no matter the road type. The difference comes when you have multiple cars trying to go down the same road.

 

It's the same with teaming - you get multiple "lanes" that are each capable of 1gbit throughput, so can achieve a max of 4gbps throughput, but no single stream will be any faster. All teaming gives you is additional capacity and redundancy.

 

So for a multi-user server its useful, but for a single point to point application if you need to increase throughput you typically need to look at using 10gb+ adapters.

[mikkydoos]

They are all RAIDed. RAID 5 in the one that I mentioned above. You all may be right. Disk limitations.

[Michael]

Not quite. Think of it a bit like a motorway vs a single lane road. If we assume both have the same speed limit, then for a single car it's going to take the same time no matter the road type. The difference comes when you have multiple cars trying to go down the same road.

 

It's the same with teaming - you get multiple "lanes" that are each capable of 1gbit throughput, so can achieve a max of 4gbps throughput, but no single stream will be any faster. All teaming gives you is additional capacity and redundancy.

 

So for a multi-user server its useful, but for a single point to point application if you need to increase throughput you typically need to look at using 10gb+ adapters.

 

I think we're on the same page - maybe it's just how I explained it?

[Muz]

Yeah NIC teaming / Link aggregation only works well for multiple flows, a single flow such as a data transfer will be limited to one member of the bundle