500 GB at 50MB/s

[timeOday]

I'm setting up a video acquisition box and would like to get the following:

- 500 GB storage
- Sustained, reliable 50 MB/s write speed
- Access time isn't an issue
- Low CPU Utilization
- Contents are preserved in the event of a single drive failure
- I don't mind a little downtime / rebooting if a drive fails
- Linux compatible (including booting)

Subject to the above, I'd like to minimize the price.

It looks like all the decent 250 GB SATA drives have sustained write
speed of, at minimum, 30 MB/s.
<http://www20.tomshardware.com/storage/20040820/hitachi-maxtor-09.html>

What are my odds of sustaining 50 MB/s with 3 such drives in RAID5 on a
decent SATA controller, such as Broadcom's RAIDCore BC4452? How about 4
drives?

I'm going to be capturing uncompressed video, so another alternative
might be 2 drives in Raid 0 plus a backup drive using lossless
compression.

..

 

[Curious George]

What are my odds of sustaining 50 MB/s with 3 such drives in RAID5 on a
decent SATA controller, such as Broadcom's RAIDCore BC4452? How about 4
drives?

My gut says no, but might be possible:
http://www.gamepc.com/labs/view_content.asp?id=r52005&page=12

4 drives or more tend to be better for raid 5
raid5 write penalty is of course an issue

4 or 6 drive raid 0+1 or 1+0 might be a safer bet.
To a lesser extent possible also 53, 5+0, or perhaps 5+1

Use a "professional" workstation or server board with a faster than
32/33 pci bus.

with streaming video or massive files the maximal data transfer rates
of individual drives that are often thrown around are possible. For
smaller files you should expect a fraction of these rates.

I'm going to be capturing uncompressed video, so another alternative
might be 2 drives in Raid 0 plus a backup drive using lossless
compression.

That would be fine even with no special raid card. Just monitor SMART
(FWIW), backup regularly,

 

[timeOday]

Use a "professional" workstation or server board with a faster than
32/33 pci bus.

I wanted that, especially because that framegrabber is going to suck PCI
bandwidth bigtime. But I also want this to be a small, portable
computer, adding to the difficulty. The framegrabber supports PCI-X 66,
but none of the small motherboards do. There is a small form factor
Shuttle with PCI express, but no framegrabbers in that format yet.

I've decided to go with a Shuttle SB81p. It has room for 3 disks plus a
DVD writer - 2 disks in RAID 0 plus a backup & system disk. The
motherboard uses the ICH6R chip with built-in RAID. Surprisingly, this
onboard chip has about the fastest Raid 0 around, with low CPU
utilization. Even better, the SATA ports do NOT share bandwidth with
the PCI bus.

 

[Curious George]

I wanted that, especially because that framegrabber is going to suck PCI
bandwidth bigtime. But I also want this to be a small, portable
computer, adding to the difficulty. The framegrabber supports PCI-X 66,
but none of the small motherboards do. There is a small form factor
Shuttle with PCI express, but no framegrabbers in that format yet.

I've decided to go with a Shuttle . It has room for 3 disks plus a
DVD writer - 2 disks in RAID 0 plus a backup & system disk. The
motherboard uses the ICH6R chip with built-in RAID. Surprisingly, this
onboard chip has about the fastest Raid 0 around, with low CPU
utilization. Even better, the SATA ports do NOT share bandwidth with
the PCI bus.

Does it really NEED to be a SFF pc? Will it the framegrabber fit?
Does the framegrabber suck a lot of juice? SFF PC's can be a little
skin-of-your-teeth for more intense use (although I understand the
shuttles are better than many & the SB81p is relatively beefy).

This could be doable just double check any space, thermal, & power
concerns.

Some companies make ruggeddized portable workstation/servers if you
NEED the pci-X, ECC ram, extra slots, etc along with portability.
They're very pricey though

 

[timeOday]

Does it really NEED to be a SFF pc? Will it the framegrabber fit?
Does the framegrabber suck a lot of juice? SFF PC's can be a little
skin-of-your-teeth for more intense use (although I understand the
shuttles are better than many & the SB81p is relatively beefy).

This could be doable just double check any space, thermal, & power
concerns.

Some companies make ruggeddized portable workstation/servers if you
NEED the pci-X, ECC ram, extra slots, etc along with portability.
They're very pricey though

I'll try to remember to report back on it. There was one board (Unigraf
UGF 01) that I liked but which was full length and wouldn't fit. The
ruggedized computers are not only very expensive, but the reasonbly
small ones lag well behind in technology, and I think a fast CPU will be
nice for compressing the video. The P-series shuttle have a 350W PSU
and are built with airflow in mind so I think it's likely to work -
though I wouldn't be the farm on it.

 

[Curious George]

I'll try to remember to report back on it. There was one board (Unigraf
UGF 01) that I liked but which was full length and wouldn't fit.

I'd also be considering a "short-length" 1u or 2u server chassis.
Still small & sleek & able to accommodate full length PCI, 4-9 HDDs,
up to eATX mobos. Cooling & power will be superior (& may even be
overkill so you could slow & silence the fans without compromising
anything)

The
ruggedized computers are not only very expensive, but the reasonbly
small ones lag well behind in technology, and I think a fast CPU will be
nice for compressing the video.

for the most part yes. Many industrial boards also lag behind on
performance.

The P-series shuttle have a 350W PSU
and are built with airflow in mind so I think it's likely to work -

Like I said this could be doable (unless you, for example, NEED a full
size pci-x framegrabber

though I wouldn't be the farm on it.

You mentioned that you won't just be capturing the video stream with
this machine but also encoding it later. The computer will be under
full load for long periods during these common large
encoding/rendering jobs.