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RAID 0 Write Speed

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September 20, 2007 2:36:07 PM

Hi,

Going to be using my system for HD video capture, and from what I understand, I will need a write speed of about 130mb/s. Will a raid 0 setup be able to handle those speeds? Was thinking of two 500gb sataII 7200 drives.

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September 20, 2007 3:55:34 PM

What is your HD source? The type of HD you're using and the editing system/software affect the data rates, because they all work in different codecs which are compressed differently.

=== Within single hard drive data rates ===
HDV (JVC/Sony) - 25 Mbps (3.5 MBps)
H.264/VC1 (MPEG-4, Microsoft) (Blue-Ray/HDDVD) - 36 Mbps (4.5 MBps)
DVCPro HD (Panasonic) - 100 Mbps (14 MBps)
HDCAM (Sony) - 144 Mbps (18 MBps)

=== RAID Array Recommended ===
HD D5 (Panasonic) - 235 Mbps (29.5 MBps)
Uncompressed 720/24p 4:2:0 - 332 Mbps (41.5 MBps)
HDCAM SR (Sony) - 440 Mbps (55 MBps)

=== RAID Array Required ===
Uncompressed 1080/24p 4:2:0 - 746 Mbps (93 MBps)
Uncompressed 720/60p 4:2:0 - 818 Mbps (102 MBps)
HDCAM SR HQ (Sony) - 880 Mbps (110 MBps)
Uncompressed 1080/60i 4:2:0 - 932 Mbps (117 MBps)

=== Professional SCSI/SAS Array Required ===
Uncompressed 1080/24p 4:4:4 10bit - 1.520 Gbps (190 MBps)
Uncompressed 720/60p 4:4:4 10bit - 1.688 Gbps (211 MBps)
Uncompressed 1080/60i 4:4:4 10bit - 1.896 Gbps (237 MBps)

Those data rates are only for capture. For editing, where multiple streams are being read and written simultaneously during rendering, higher speeds are required.
September 20, 2007 5:10:22 PM

Hi,

It would be 4:2:2 at 480i/30FPS, 480p/60FPS, 720p/60FPS, 1080i/30FPS. As for the capture format, unsure of what codec is supported. From what I understand though, uncompressed should be allowed.

And yes, I would be editing too.
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September 28, 2007 12:58:34 AM

SomeJoe7777, would two or four 500gb sataII 7200 drives in a RAID 0 be enough for what I would be working with?

Also, how much slower is RAID 5 vs RAID 0?
September 28, 2007 2:53:26 AM

If you're working with uncompressed video, you need to ask your editing station/editing software manufacturer what they recommend. Frequently, with high end editing systems, the manufacturer has tested their software only in particular system configurations. They won't support you if you deviate from their recommended setups.

Four drives in a RAID 0 can be fast enough for uncompressed capture and uncompressed editing if it's done correctly (i.e. proper motherboard and chipset, proper RAID card and interface, etc.)

RAID 5 can be quick for sequential access with the right RAID card (the 3Ware 9650SE can do 600MB/sec writes in RAID 5 with 12 drives). RAID 5 random writes are always slower due to the limitations of write combining. RAID cards with large amounts of cache can help the overall speed by allowing more write combining.

To really make a quantified statement as to how much speed you're going to need, we need to know the editing platform, codec it uses, and tape formats you'll be working with. If it actually works with 4:2:2 uncompressed video, you definitely need to get the technical requirements from the editing software manufacturer instead of trying to build something yourself.
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