Raid for high def (raid 0+1 or raid 5)

[SlothPaladin]

A while back I came to these boards to get some advice on building a computer for high definition editing. The plan was to build something that could edit 1080 24p 4:4:4 video. At the time I was only ready to buy the core system components as I could not afford the costs of a proper raid setup. (a big thanks to everyone that helped, it is the best computer system I, and everyone I know, has ever used. It's so stable, and VERY fast)

Well I just bought the Areca ARC-1220 and an internal battery backup for it and 7 320 GB hard drives, they are now in the mail. I plan on using Premiere CS3 and having all the video files on the raid drive and the audio files on a 150GB Raptor I have, I will only use 6 drives for the raid array and the 7th will be in case of drive failure. I've always heard that raid 0 is the way to go for video editing, but looking at the speeds of raid 0+1 vs raid 5 the read speed of raid 5 is wonderful, however it does seem to suffer when it comes to write speeds. If I'm looking at 6 MB a frame then I need to be able to read at 144 MB/s to watch the video without any framed dropped which both setups should be able to achieve without problem. My big question would the worse write speed out way the extra space gained on the raid 5? I imagen most of my renders will be from the raid drive to the raid drive and according to those charts the raid 5 gets between 155 and 181 MB/s while the raid 0+1 gets 214 to 229 MB/s, and my guess is that the write from/to the same drive will slow those numbers down a bit more (is that correct?).

As far as space in concerned I'm dealing with animated shorts which means I will have a lot less footage then live action projects, it would be unlikely for me to work on a project over 25 minuets in length on this setup, and if I had 3 copies of each shot (I usually have 2-3 copies of a given shot) on the array that would only be about 635 GB so ether setup should have enough space for my current needs.

Just one last question, the ARC-1220 card says it supports 'Multiple RAID selection' does that mean that I could have 6 drives plugged in for my video set up and then plug in 2 1TB drives and put them in a raid 1 for backup purposes? I'd like to add something I could back up safely to in the system. So long as I wasn't using that drive while editing video it wouldn't effect my performance would it?

 

[UncleDave]

A rough guideline is that the more spindles (hard drives) you have the better the throughput will be. Ultimately you will get to the next bottleneck which may be bus, CPU, etc.

A very very quick comparison between different RAID levels:

RAID 0 - data is "spread" across all drives - no redundancy - fastest
RAID 4 - one drive always holds check sum data remaining drives hold data - full redundancy - faster to write than RAID 5 still slower that RAID 0
RAID 5 - data and check sum data is "spread" across all drives - full redundancy - faster read than RAID 4 still slower than RAID 0

RAID 4 & 5 need to calculate the check sum data, RAID 0 doesn't hence the difference in writing.

So it comes down to do you want the redundancy or not? If you do then I would say go for RAID 5, if not then go for RAID 0.

If you only have one RAID controller then: yes reading and writing to it will impact your throughput. Your best performance option is to have two controller cards and two RAID arrays.

I can not advise you on the card.

 

[Seraphic]

SlothPalad, interesting topic since I'm also building a system for HD video. But, I'm interested to know, what capture card are you using? There aren't that many that support 1080p. Also, what price did you get for the 320gb drives? I was looking at a few 500gb, but the cost is somewhat up there.

But as to your raid question, I would suggest a raid 0 for the fastest write/access speed you can get. Use the main raid for the OS and video editing, then a drive or two off raid, for backup.

 

[enlightenment]

6 disks in a RAID5 will leave you with plenty of write speed on an Areca, formula:

theoretical write speed = (number_of_disks - 1) * throughput of slowest disk * raid5 driver efficiency

In your case this might be: (6 - 1) * 70MB/s * 0.80 = 280MB/s, guessed at 80% efficiency. You may need to tune settings to get optimum speeds though, to allow parallellization to occur. Also, think about buying BBU for write-back.

 

[GrievousAngel]

What about using two RAIDs? Do they have to be the same configuration? Similar is anmy way?

I already have a HighPoint RR4320 with 4 10k SAS in RAID5, and I just ordered a HighPoint RR640 + 4 SATA III 6Gb/s 7200 64Gb cache HD so I can get into the newer & cheaper SATA III 6Gb/s 7200 HDs. My question is what may be the best configuration for me to use based on my main purpose is audio recording & editing + video editing?

Do you think the ASUS AMD Phenom II X4 955 3.2GHz with 8Gb ram will keep up? Is this a good time to move into a faster CPU system?

What advice might you pass hold?

Thanks,
William

A rough guideline is that the more spindles (hard drives) you have the better the throughput will be. Ultimately you will get to the next bottleneck which may be bus, CPU, etc.

A very very quick comparison between different RAID levels:

RAID 0 - data is "spread" across all drives - no redundancy - fastest
RAID 4 - one drive always holds check sum data remaining drives hold data - full redundancy - faster to write than RAID 5 still slower that RAID 0
RAID 5 - data and check sum data is "spread" across all drives - full redundancy - faster read than RAID 4 still slower than RAID 0

RAID 4 & 5 need to calculate the check sum data, RAID 0 doesn't hence the difference in writing.

So it comes down to do you want the redundancy or not? If you do then I would say go for RAID 5, if not then go for RAID 0.

If you only have one RAID controller then: yes reading and writing to it will impact your throughput. Your best performance option is to have two controller cards and two RAID arrays.

I can not advise you on the card.