I have made some real world, non-scientific tests of i/o speeds of iscsi and different network protocols in OS X.
My setup:
- Early 2011 MPB runnig OS X 10.7 Lion, connected to Netgear gigabit
switch
- Qnap TS-419P II NAS with 4 disks in RAID5, connected to Netgear
gigabit switch
- Buffalo LinkStation Pro NAS with 1 disk, connected to Netgear gigabit
switch
- globalSAN iSCSI initiator for OS X was used for iSCSI tests
The test was made by copying (cp) about 2gb of camera raw files (each about 20-25mb in size) to the device, restarting the device and copy the same data back to local SSD drive.
Write performance:
- Qnap, Async NFS = 34.59 mb/s
- Qnap, AFP = 31.83 mb/s
- Qnap, ISCSI = 31.89 mb/s
- *Qnap, SMB, cp = 30.71 mb/s
- Qnap, NFS = 27.22 mb/s
- Buffalo, AFP = 10.07 mb/s
- *Qnap, SMB, mv = 3.93 mb/s
*) Only when using SMB I got very different write performance results from copying the files to device using cp or mv command!
Settings the async option for NFS greatly improves the read performance.
I use the following mount command for the test:
mount -t nfs -o resvport,soft,intr,rsize=32768,wsize=32768,timeo=900,retrans=3,proto=tcp,vers=3,async server:/share /private/share/
Read performance:
- Qnap, Async NFS = 71.99 mb/s
- Qnap, AFP = 67.44 mb/s
- Qnap, ISCSI = 60.22 mb/s
- Qnap, NFS = 46.51 mb/s
- Qnap, SMB = 35.82 mb/s
- Buffalo, AFP = 5.46 mb/s
The protocols seems to handle caching differently. This is the results I got when copying the files to the device and immediately back to the local SSD drive (without restarting the device)
Read performance - without restart
- Qnap, ISCSI = 151.71 mb/s
- Buffalo, AFP = 145.54 mb/s
- Qnap, AFP = 143.23 mb/s
- Qnap, Async NFS = 71.99 mb/s
- Qnap, NFS = 47.37 mb/s
- Qnap, SMB = 38.13 mb/s
My conclusion: I will use either AFP or NFS since both protocols gives similar performance and flexibility (compared to iSCSI) for my purposes (Lightroom, backup, media streaming)