RAID level suggestions

[shocky123]

I am curious as to what people would recommend for a raid implementation.

I have:
dual opteron server(s) -to be used as a file storage server to take load off
of supercomputers, and provide some file storage
for network
8x450Gb WD 7200RPM 8MB (yes, 450)
3ware 9506 serial ATA Raid controller
all other HW is beyond top-of-the-line.
running Linux 4.6.6,


So far, all hardware raid levels have provided less than satisfactory results, so I will be implementing software raid here.
Read-rate is most important, then redundancy, then write rate.

I guess the real questions here are.. has anybody ever seen an implementation of RAID 50....(0+5,5+0) at a software level?
...and/or ...
would there be any benefit over a classic sw-RAID 5 configuration in terms of Read rates?

thanks

[Jeffbx]

I doubt you'd ever get a software RAID to out-perform HW RAID. If performance is sub-par, here are the things that I would recommend to fix it (unfortunately, none of them involve the hardware you're using):

1. Switch to SCSI. You'll never get the throughput you're looking for from IDE disks in that config. Those things are probably running at 5400RPM.

2. Switch to a better RAID controller. Nearly all of the good, high performance cards are SCSI controllers. You'll want one with a big on board cache (64 or 128MB) running at ultra 320 speed.

3. Replace this with a NAS unit - this would be a rather significant investment, however. Maybe $50-100k to match the storage space you have. Speed will blow this one away, however. Look at Sun or Network Appliance, or even EMC for a SAN solution.

The one suggestion I would make to improve the speed of your current hardware would be to create a seperate array for the OS... make a RAID1 mirror with a couple of small drives for the OS & any apps, and put the swap file & all data onto the RAID5.

[shocky123]

I am working in a research program, unless you are referring to a degraded drive or something, they are actually 7200 rpm disks. The controller is a 128MB 3-ware 8disk Escalade 9506 model, (which retail around $500) and has the general trend to provide fairly decent write speeds, but lacks when it comes to read speeds.
As far as OS is concerned, I'm using an infini-wire capable of over literally 400MB/sec, and we netboot while i'm still testing the configs here, so OS is not local, nor part of the array(s).

Performance wise, so you can get an idea of what I'm dealing with... w/
W-I/O R-I/O (these are sustained read/writes
over a 10Gb test)
HW RAID 5 ~101.5Mb/s ~71.2Mb/s
SW RAID 5 ~68.9Mb/s ~111.3Mb/s

unfortunately, as you said though, with my hardware..(which I cant change)
I'm limited via the HD interface albeit ATA or SCSI. Ideally, I'd like to get the Read i/o somewhere around 175, though I doubt that is possible, as SW-RAID0 only gave 198Mb/s read.

any further ideas?

[LegendKiller]

HW RAID 5 is going to be your best bet. RAID 10 is rather slow. What interface is the 3ware card running?


LK

[shocky123]

HW RAID 5 is going to be your best bet. RAID 10 is rather slow. What interface is the 3ware card running?


LK
64-bit pci @ 66Mhz
I have the drives setup via the 3ware card as 8 single units.

[shocky123]

I got the (probably bad/stupid) idea that there could be a possibility to take 8 drives, make two 4-disk raid-5 arrays via hardware, and write a software raid configuration that takes the two arrays, and uses raid 0 on a software level..

I'm sorta novice with these things, so I was just wondering if I'm waay outta line, or if there is a way to implement both hardware and software raid at the same time? Anybody?

[Jeffbx]

I think you're looking too deep. For the priorities you have (fast read, redundancy & the write) I don't think you'll do better than plain 'ol RAID5. The limitation you're facing today is the hardware you're using, not the RAID setup, IMHO.