What can reduce Gigabit maximum theoretical speeds ?

[enr00ted]

Update 1:
- Changed network image (For some reason the Jumbo frames option was not active in my Laptop). Increase in speed but still below maximum.
- Added switch configuration images.
- Added NAS configuration images.
- Added technical specs for laptop/nas.

Hi everyone,

I believe this has been discussed for a long time, but how can someone benchmark his own lan ? I mean how can one find the bottleneck if any ? Also I am not a network expert nor I have too much experience as I've only recently switched to Gigabit and playing with it. How much of the theoretical speed do you actually loose ?

A small test case I've been doing, a common task in my home lan:
- Windows 8.1 upt-to-date
- All up-to-date firmwares
- Up-to-date DSM on Synology (2 HDDs, RAID 1, the mirroring one)
- Large file test > 700 MB (to test the maximum limit)

Laptop/Nas specs:

Switch configuration:

Synology DS213j configuration:

So, Gigabit has max of 1000 Mb/s right ? That is 125 MB/s aproximately right ? What is the reason that I am so far away from that value ? Is it the cable ? The multiple hops ? The HDD/SSD ? The RAID ? The specs of my equipment ? Maybe these are normal values to be expected ?

 

[System Error Message]

I use softperfect ramdisk to create a ramdisk and than transfer files over the network to another ramdisk.

Make sure to use good cables not the copper clad cables and keep them away from intereference like electricity.

Make sure your NICs are configured properly and that both systems have a fast enough CPU.

The other benchmark would be iperf or even mikrotik bandwidth tester (CPU heavy).

 

[L&LD]

Is that a single 700MB file? Or multiple large files that add up to ~700MB's?

If so, try different files in your tests. A single very large file is the best test for maximum throughput speed.

If that isn't the issue, I would disable the Jumbo frames on all your equipment and reboot everything at least twice. Then test again.

If this doesn't get you closer to the maximum theoretical speeds with your specific equipment, consider the fact that you may already be maxed out. In my ssd based office with new computer platforms and lots of ram, the best case speeds cap out at ~113MB/s, for example. While I would love an additional 10% increase in performance, I am still happy with my network as is.

 

[enr00ted]

Is that a single 700MB file? Or multiple large files that add up to ~700MB's?

Single file, multiple files or small files drastically decrease speed to around 30MB/s

If that isn't the issue, I would disable the Jumbo frames on all your equipment and reboot everything at least twice. Then test again.

But they should, in theory, speed things up, right ?

If this doesn't get you closer to the maximum theoretical speeds with your specific equipment, consider the fact that you may already be maxed out. In my ssd based office with new computer platforms and lots of ram, the best case speeds cap out at ~113MB/s, for example. While I would love an additional 10% increase in performance, I am still happy with my network as is.

Is RAM that important on file tranfers ?


Will having SSDs on the NAS and maybe a different RAID speed things up ? Can the single core cpu on the NAS be a bottleneck ? Having a quadcore cpu on the laptops make any difference ?

 

[azazel1024]

What Synology? Especially some of the older NAS most certainly CANNOT handle 1Gbps of throughput. Most of the newer ones with large files should come close or can handle a 1Gbps pipe.

Keep in mind, they are VERY lightweight processors in those appliances in comparison to even a lightweight desktop or laptop (or hell, my TABLET has a much beefier processor with its z3470 in it), especially the 1 and 2 bay NAS and even most of the 4 bay NAS.

The theoretical maximum performance with NO L7 overhead (application layer) is roughly 115-116MB/sec with 1500MTU (regular TCP frame size), which is about 920-928Mbps. With 9k Jumbo frames this increases to roughly 120-121MB/sec, roughly 960-970Mbps.

SMB2+ has very little overhead though, figure at most a 1% hit.

A lot of other stuff can come in to play though. Congestion control, TCP/IP windowing, pause for ACK packets, etc.

The BEST I have seen is roughly 118-119MB/sec in real world SMB file transfers utilizing TCP/IP (It can use UDP, but there are some other issues with that and it doesn't necessarily increase real throughput).

Generally performance lower than this is caused by misconfiguration, poor adapter performance (but unless there are actual ISSUES, a crappy adapter is generally no worse than maybe 3-5% slower than a good one) or a CPU/storage layer that cannot support high enough speeds to stuff a 1GbE pipe.

 

[enr00ted]

Synology model DS213J. Old model I know . I updated the main thread with a bit more information.

 

[azazel1024]

The DS213J can't hit gigabit speeds. CPU limitations.

From a few reviews of it that I have seen you are limited to around 70MB/sec reads and 60MB/sec writes +/-5MB/sec for the DS213J.