PC Specs and RAID Question - Please help

[Kareem Dimashkie]

Hi Everyone,

I am putting together an editing PC, and had a question about my RAID configuration

CPU
Intel Core 2 Quad Q9550 Yorkfield 2.83GHz LGA 775 95W Quad-Core Processor

MB
ASUS P5K PRO LGA 775 Intel P35 ATX Intel Motherboard

Hard Drive (in Raid 5 Configuration) (for both OS and SCRATCH disk)
4 x Seagate Barracuda 7200.11 500GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM

RAM (8 GB total)
2 x G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit

Video Card
NVidia Quadro FX1700 512MB 128-bit GDDR2 PCI Express x16 Workstation Video Card



So, first off, please let me know what you think of the specs. Second, I was wondering how you felt about the RAID configuration. Is it optimally better to buy two more hard drives for the OS and put them in a RAID 0 configuration? That would mean the RAID 5 configuration would be the Scratch Disk only, and I would probably reduce it to three drives instead of four.

I really didn't see the point of an internal media drive, and figured I would just purchase an external firewire drive. Any benefits to an internal media drive?

Thank you for your time and advice.

[Harm Millaard]

First, get a separate physical disk for OS & programs.
Second, use an internal Raid0 (two disks) for media. You can always recapture in case of a disk failure.
Third, use the Raid5 for projects, scratch, export and other stuff.

Firewire external disks are about 3 times slower than internal SATA disks, so only use those for backup. An internal SATA 2 disk Raid0 is about 6 times faster than firewire and USB is even worse.

[Kareem Dimashkie]

Originally Posted by Harm Millaard

First, get a separate physical disk for OS & programs.
Second, use an internal Raid0 (two disks) for media. You can always recapture in case of a disk failure.
Third, use the Raid5 for projects, scratch, export and other stuff.

Firewire external disks are about 3 times slower than internal SATA disks, so only use those for backup. An internal SATA 2 disk Raid0 is about 6 times faster than firewire and USB is even worse.

Thank you for the advice Harm. Can you tell me what is the technical reason for getting a separate physical drive for the OS and programs? I take it you meant it shouldn't be a RAIDED drive. So a regular 7200 RM drive would do the trick?

Additionally, what's a good size for media drives and scratch drives? I know it's pretty relative to the user, but I just got a Canon XH A1 and will be shooting a lot of hi def film at 1080i.

[Kareem Dimashkie]

Additionally, why not just RAID a bunch of drives all together? I still don't see why it's beneficial to separate the drives. What's the better scenario?

6 x 7200 RPM 500 GB Hard Drives in RAID 5 configuration

vs.

2 x 7200 RPM 250GB Hard Drives in RAID 0 (OS)
2 x 7200 RPM 500 GB Hard Drives in RAID 0 (Scratch)
3 x 7200 RPM 500 GB Hard Drives in RAID 5 (Media)

What's the better configuration? I'll be using AVID Media Composer to edit.

[Harm Millaard]

For OS & programs 80 GB is enough. You don't want to take any chance of disk failure requiring you to re-install everything.

(R)aid0 means simple striping of 2 or more disks. If one of the disks fail, you lose all data. Hence the (R) because there is no redundancy.

Why a separate drive for OS & programs? Well, imagine you are driving your car, your wife is in the back with your youngest child and they want you to tell something that happened to you yesterday, meanwhile your boss calls you on your cell phone, so you answer it. Doing these three things at the same time (driving, talking and making a phone call) is not very safe. It would be much better if your wife was driving, you were in back and handed your child a toy or book, telling her/him to wait a minute and answer your bosses call.

The same applies to disks in your system, OS & programs are accessed continuously. While editing you need your media file, your project file, your rendered files, temp files etc. Better to delegate some tasks (like driving) to another disk, than having one disk try to do three separate things at the same time.

For editing I would suggest at least 3 disks, one for OS, one for media (could well be either a Aid0 or a Raid5 with at least 3 disks) and one for projects/scratch.

[Kareem Dimashkie]

Originally Posted by Harm Millaard

For OS & programs 80 GB is enough. You don't want to take any chance of disk failure requiring you to re-install everything.

(R)aid0 means simple striping of 2 or more disks. If one of the disks fail, you lose all data. Hence the (R) because there is no redundancy.

Why a separate drive for OS & programs? Well, imagine you are driving your car, your wife is in the back with your youngest child and they want you to tell something that happened to you yesterday, meanwhile your boss calls you on your cell phone, so you answer it. Doing these three things at the same time (driving, talking and making a phone call) is not very safe. It would be much better if your wife was driving, you were in back and handed your child a toy or book, telling her/him to wait a minute and answer your bosses call.

The same applies to disks in your system, OS & programs are accessed continuously. While editing you need your media file, your project file, your rendered files, temp files etc. Better to delegate some tasks (like driving) to another disk, than having one disk try to do three separate things at the same time.

For editing I would suggest at least 3 disks, one for OS, one for media (could well be either a Aid0 or a Raid5 with at least 3 disks) and one for projects/scratch.

Thanks for the response, Harm. I think my biggest confusion lies in how each drive is utilized during the editing process.

Even if the media and scratch drives get accessed simultaneously, you still get 50% performance out of the RAID 5 configuration.

According to the Tom's hardware chart on RAID Drives, we are getting better performance using RAID 5 with 6 hard drives than a 2-drive RAID 0 configuration.

It's not that I'm a proponent of either RAID configurations, but I am curious as to why a RAID 5, 6-disk setup would be less ideal than a Raid 0 OS, Raid 5 Media, Raid 0 Scratch configuration.

Here is the chart from Tom's Hardware
RAID Scaling Charts, Part 1 : RAID Testing With 2-8 Drives - Tom's Hardware

Thanks again for your help.

[Harm Millaard]

As a very rough rule of thumb, a N disk raid0 will have slightly more speed than an N+1 disk raid5 array. This depends mostly on the logic used for the parity calculations. The speed difference will be very slight when the raid controller uses an advanced chip like the IOP 348.

Given the option of a 6 disk raid5 (if your case, PS and cooling are up to the task), that is a pretty straightforward solution. This a fast enough for intensive HDV editing. One thing to consider is that for media files you will benefit from large stripe and chunk size, but for rendered files that could easily be smaller. Just experiment to find the solution that fits your needs best. I maintain the need for a separate OS disk.

A 6 disk raid5 would likely require a dedicated controller card. If that is the case, I suggest the Areca ARC 1680iX-8 or 1680iX-12. The 12 has the advantage of allowing a larger cache to be installed, up to 4 GB, the 8 has only 256 MB cache.

[Kareem Dimashkie]

Thank you very much, Harm.

[Mike McCarthy]

Definitely run your OS on a dedicated non raid disk. It is easier to install and backup software on a single spindle volume. Once you have a backup image of the installed OS drive, there is no need for redundancy. All other operations can be run from a single fast volume. Four disks is a good number, with the Raid 0/5 decision being based on the level of financial importance of the files you are working with. Can you afford to lose/rebuild them? If an occasional backup to an external firewire drive is enough safety, RAID0 is way cheaper. If not, invest in a good Raid 5 system. The simplest interface is internal SATA, unless you need more than about 4TB of storage.