Drop in iSCSI performance

[Tekkie]

After reading the wiki on how to get iSCSI working I am happy to say its all good, mutual CHAP etc. all running just fine.

Although why the secret is shown in plain text in the UI is a mystery to me but I can live with being the system is at home.

However the performance degradation when transferring more than 1 file is worrying. The first file in a set of 2+ is transfered at 20MB/sec over a 802.11n connection from my laptop which is not too shabby I'd say, however the second file slowly drops down to 2-3MB/sec.

If I cancel the copy for the second file and start copying the second file it also is transfered at 20MB/sec.

Could this be because of WLAN issues? Or is there some iSCSI problem?

 

[SoftDux-Rudi]

iSCSI does have some TCP/IP overhead, but then again NFS and SMB also have their own network limitations and may not necessarely be any better.

Did you test the same transfers to an NFS & SMB share?
If so, what performance differences do you see?


The major problem you're having though has todo with your WiFi connection. WiFi generally doesn't offer full duplex like LAN does, which is why the 2nd copy drops in performance.

I see the same issues when I transfer data from my Laptop to my home NAS. Yet, when I transfer data from my PC to my NAS I get about 70-80MB/s constantly.