What's the bottleneck of my NAS?

Question

Hi, 
I currently own a homemade NAS.
It has a AMF 690G chipset, an Athlon 4450e underclocked @1ghz and 1 gb of memory.
HDDs are 4x WD GP 1 TB in a raid10 setup.

5 other computers are linked to this NAS.
All have a gigabit onboard ethernet, switch is gigabit too and all cables are cat 5e.
OS is freenas.

The best rate I can achieve (with a large samba transfer) is about 15-20 MB/s.
I tried to change the setup in a SAN-like network, using iSCSI, but it's just a little faster (19-22 MB/s), even with large ntfs clusters (8 or 64kb). Even tried raid5, performance is about the same.

It doesn't sounds very fast to me, so I wonder: what's my bottleneck?
Cables? Switch?
HDDs? Sata (onboard) controller? ethernet adapters? memory? OS?

Is it a software issue or should I upgrade a part ?
Of course I know everything would be faster with a fibrechannel network and scsi drives, but that's way too expensive...

Thank you

Adrian · Accepted Answer

maybe the NIC in the NAS server. You say it's gigabit, but check the settings, maybe it defaults to 100mbit. Onboard NICs are usually not as fast as some higher performance NICs. However, if data transfer is 20MBytes/s then you are running at least 160mbit, maybe close to 200.
How long are the network cables to the switch? cat5e will be ok for shorter runs.
Other guess is SATA controller and how it handles the raid10. If you can, do the tests with just one drive, no raid, and see if that's any better (or the same)
What's the speed with a FTP transfer? maybe the overhead of Samba is causing the bottle neck...
Good luck...

Edit: FreeNAS says it only needs 32 or 64MB memory, so you have more than enough. Some people need 128 or 256 if "Full" version, not Imbedded.The CPU "should" be ok too...

Second Edit: Their specs:
 What is the minimum system requirements ?

CPU

    * Pentium processor or equivalent (Minimum requirements).
    * Pentium 2 (suggested).
    * Pentium 3 or equivalent (suggested for software raid ).
    * Pentium 4, Dual Core, Quad core.(for large storage volumes and high traffic).

Memory:

    * 64 MB Ram for Xbox 'full' install version plus swap enabled.
    * 128 MB Ram , minimum Ram required for 'embedded' version.
    * 256 MB Ram required for iSCSI targets.
    * 512+ MB Ram for very large volumes 1+ TB storage

DeFtOnEs · Answer

My guess would be just lack of processor power to pump the data.

What's the bottleneck of my NAS?

2 Answers