Harddrive read/write speeds

Cyber Akuma

Cyber Akuma

Gawd
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Jan 3, 2009
Messages
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I tried to Google benchmarks on this but wasn't able to find any good results.

I want to know about harddrive read/write speed comparisons.

I can't afford SCSI drives, so, assuming all drives are SATA 3Gb:

And assuming one is using a good hardware-based raid card instead of the on-board motherboard raid (which I hear is software based and slower).

How much faster would a RAID 0 setup of 7200 RPM drives be compared to a single 7200 RPM drive connected to the motherboard?

How much faster is a 10,000 RPM drive to a 7200 RPM?

What about comparing a 7200 RAID 0 array to a single 10,000 RPM drive?

Is the speed of having two 10,000 RPM drives in RAID 0 worth it over a single 10,000 RPM drive?

The reason I am asking is because I want to buy this capture card:

http://www.blackmagic-design.com/products/intensity/

From what I understand, this is the ONLY capture card I could find that can capture in HD from HDMI or Component (And dosen't cost over $1000 with its intent being for professional studio work).

When capturing, I capture in RAW uncompressed format then encode it.

How much write speed would I need to ensure I can capture 1080P RAW video uncompressed without any framedrops? (I assume a modern i7 CPU based system should have enough processing power to pull this off?)

Would I need to have a separate scratch disk just for capturing?

I would prefer to use my OS drive, but with the OS and page file running off the same drive, somehow I doubt this would work no matter how fast I can make it will it?

If I have a RAID card that can support four drives, and make two seperate RAID 0 arrays on it (Say, one for my OS/page drive and one as a scratch array for video capture), would the use of one array effect the speed of the other?
 
Browse through this entire thread on HD Tune results a bunch of us have submitted. It won't necessarily answer your specific questions but you should have a much better idea, and it's this sort of knowledge that many of us would base our own answers to you on.

http://hardforum.com/showthread.php?t=1284410
 
Problem is I don't know what kinda speeds I would need for this kinda video capture, and how much swap/os use on the same drive I am capturing on would impact the capture.

Plus from what others told me, there is a big difference between linear read/write and random access. Clearly linear writes would be what a capture operation would use on an empty disk (provided I empty the capture drive after I am done with the capture operation).

About the random access though.... what about speeding my OS loading/access and videogame load/access times?

7200 vs 10000 and no raid vs Raid 0, would any of those help in this scenario?

And at what point would it be pointless? (e.g. would a raid 0 10,000 setup be a near pointless spead increase over a raid 0 7200 or a single 10,000?)
 
i would use a Western Digital Black 640gb drive...... 2 in RAID 0 would give 200+ mb transfer and over 1TB drive for $150
 
The new Samsung 1TB HD103UJ drive has sustained write speeds almost identical to its read speed and those are fast!
HDTune reports read speeds of 116MB/s max, 53MB/s min, 92MB/s avg
They are really quiet and great drives for a low price.
 
Just so you know, that capture card won't do 1080p. Also, higher RPM doesn't necessarily mean an increase in read/write speed. Capturing RAW 1080p is above anything consumer level to be honest. Do you even have a source for it? Also, most professional stuff doesn't use HDMI, but instead HD-SDI.
 
I was mainly planning to capture from Component with HDMI being a bonus.

That card can't do 1080? ARGH! I wasn't aware of this, what is the highest it can do?
 
According to this article, Blue Ray quality is 54 mbits/sec. If you want to be conservative then that would be less than 10 mbytes/sec. Now, I do not know if Blueray uses any kind of compression, but assuming they do, you are looking at some serious storage requirements if you want to go above BR quality.

Any modern hard drive can manage these kind of data rates though. 10k drives do not help much with data throughput rates. They only decrease the seek time. Raid 0 does not help the seek time, but can almost double the data throughput of a drive.

Now, if I was building a system for some serious video editing, here is what I would do. Get a Vraptor for the system drive just because. Get 2 storage drives. 1 to capture the video to, and a second to store the video to when you encode it. Remember though, any modern hard drive can easily manage video encoding rates.

Don
 
I want HD video capture to be one of it's abilities, but that will sorta be an extra, its main purpose is to be a high-end gaming rig and storage array.

Space AFTER encoding should not be an issue since I am planning to use a RAID 5 array with at least 4 1.5TB drives in it for storage, I just needed a temporary place where I can flawlessly record uncompressed HD video at maximum quality settings without encountering framedrops.
 
Assuming 16-bit color (I think most video capture is 24) for 1080p uncompressed at 30 FPS for 1080p you would need:

1920*1080*16*30 =995328000 (995 megabits).

Assuming 24 bit color and 60 FPS you would need:

1920*1080*24*60 =2985984000 (2.98 gigabits)

My raid6 array can write at about 570 megabytes/sec which is about 4.78 gigabits. Assuming the worst case senario you need a raid array capable of writing at 2.98 gigabits: or 355 megabytes/sec.

Assuming 24 bit color and 1080i you would need:

1920*540*24*60= 1492992000 (1.5 gigabits) or 177 megabytes/sec. Assuming high end 7200 RPM HD's and you wanted redundant raid you would need atleast 4 hard-drives (in raid5).

Another thing to keep in mind is depending on what your source is you might be able to convert 1080i@59.97 FPS to 1080p @ 24 FPS as some content is telecined and can be converted to a true 1080p format. My digital camcorder is like this. When it records in 'progressive mode' the format it writes the file is still 1080i and has to be de telecined to get it to 1080p @ 24 FPS.
 
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