Raid For a NAS box and theoretical speed

Ultim8

Ultim8

Ultim8

Associate
Joined
27 Nov 2008
Posts
669
Location
UK
a quick question. Im swapping some stuff around and im going to turn my server into a video editting machine and take all the hard drives out and make a mini itx freenas box.

Now my network is all gigabit lan so in real world terms gigabit lan can transfer things at say 125MB/s with overheads i believe. Now in my freenas im deabting what type of raid to use. However a single Seagate 7200.12 gets speeds of 120MB/s so why would anyone raid 0 on a NAS?
 
What speeds you actually get over gigabit depend on quite a lot of factors, such as the network cards involved. What speeds you can currently push data around your network at should be a reasonable approximation to best case speeds from a nas.

Raid 5 is the obvious answer to your question however. Your Seagate isn't going to manage 120MB/s most of the time (or possibly any of the time), during random reads and writes things will be much slower. I believe a four disk raid 5 should be fairly evenly matched with a good nic, without using a dedicated raid controller.

I'm in the process of moving hard drives around, so don't currently have a raid 5 running. Linux configuration uses mdadm which I was impressed with and would recommend as a viable alternative to dedicated hardware.

A slightly tricky question is whether to go for an atom based system, or a low power desktop dual core. I'd be interested in any benchmarks people have run on raid 5 + atom nas systems, as I'm finding it difficult to find sources.
 
Hi Jon,

Thanks for the answer, and i too would be interested to see performance results of a parity raid setup with an atom to see if it would affect its speed.

And in hdd bench marks i have run they show min average and burst speeds on my hdd's. And average was 120mb/s with min being 117mb/s. Are you saying these are not real world speeds? If so can you explain to me why not.

Thanks Again
 
If you don't mind im going to quickly hijack your thread and maybe you can help, I've got an icybox which was donated to me, connected direct to my PC via GB. Transfer speeds are dismal at 4.2MB/sec.

I'm running it in RAID1 on 2 x WD 750GB disks. I've done a fair amount of playing with network settings to try and speed it up but i notice the network bandwidth is never going over a max of 12% usage as well as spiking constantly (1 second it'll go up to 10% the next it'll go to 0% even though it's copying one large file)

Any ideas?

EDIT:
This is the annoying spiking
s2gv86.png
 
exactly why im building my own nas box. i had a netgear nasduo and thought that was bad so bought an icybox.....i get around 8mb with raid 0 which is worse than the netgear to be honest.

They advertise gigabit lan ect on these cheap units but in reality the speed is rubbish due to a poor processor, memory.

Unless you spend several hundred quid you dont get a lot of performance.
Im going to build a cheap mini itx box with 4 drives and run an embedded freenas on it.
Freenas is a linux build designed to be used as a nas and it does it extremely well.

Edit: A lot of people put old hardware to use by building an old system up and putting freenas on it, it may be worth considering next time your having a clear out.
 
Cheers Ultim8, in that case i might flog the icy box in a few weeks or something and get myself a low powered atom pc or something. Electric bills are a major factor for me so must make it a cheap solution :p

May even wait for those new AMD bobcat chips if they are any good, no idea when they're released though.
 
Sequential reads and writes are different to many real world uses, where the head has to physically move back and forth across the disk. I'm fairly certain you wont get an average of 120mb/s from your hard drive, though if only one computer ever accesses the drive and it doesn't try to do read and write simultaneously it's possible.

That's pretty nasty mrbios. It's plausible that the icybox is that rubbish, do reviews think it's a decent unit?

The diy home server approach does work rather well. I'm trying an all in one unit from tomorrow as a replacement, worst case scenario it'll be relegated to an offline (and possible offsite) backup. It comes with a 1ghz low power processor and 256mb of ram, so I'm hoping it isn't as rubbish as it might otherwise be.

If buying dedicated hardware for a nas, avoid realtek network chips.
 
yeah the brazo's is out very soon i get my samples week 10 and they go into mass production week 13.

Yes i have heard the same about realtek something to do with it using the cpu to process the data where as an intel nic does the processing on the nic?

Did you go for the synology box by any chance Jon?
 
You must log in or register to reply here.
Back
Top Bottom