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Raid 0 - 3 vs 4 drives and 16MB vs 32MB Cache

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January 5, 2008 6:29:12 PM

Hi,

Was looking at doing a raid 0 in an upcoming system for HD video capture/edit.

For $339.96, I'm able to buy four 320GB drives and for $359.97, I'm able to buy three 500GB drives.

So, I'm interested to know, which would perform better for video work and a raid 0 setup? I mean, I've always heard that more drives in a raid net faster speeds. However, the 7200.11 drives are newer, have less platters (from what I hear), and have 32MB cache vs 16MB of the 7200.10 drives.

What would be suggested in this case?

Four drives in raid 0
Seagate Barracuda 7200.10 320GB 7200 RPM 16MB Cache SATA 3.0Gb/s
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Three drives in raid 0
Seagate Barracuda 7200.11 500GB 7200 RPM 32MB Cache SATA 3.0Gb/s
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Thanks
January 5, 2008 6:34:33 PM

For a home theater RAID speed is not needed.

You can record at least 5 HD streams on a single hard drive without any problems.
January 5, 2008 10:51:03 PM

Before i answer your question, do you really need RAID? There is no point in getting it if your video editing, and its being bottlenecked by your CPU or lack of RAM. RAID does make sense if there is no there is no other bottleneck, and you need the IO or raw speed. Ie, running several virtual machines, editing 32-but audio files @ 2.7GB each, etc etc.

In the case that you do need RAID:

I'm not sure about the average read/write, access time, buffer speed of the drives, so i'll look at it from a generic point of view.

Go for the 4x 320GB disks. Cache size does not make that big an effect on hard disk performance. Years ago, 2MB vs 8 MB was indeed substantial, but with modern disks, 16MB cache disks can outperform 32mb disks. Also, you will get higher throughput with 4 disks.

e.g. if the 320GB disks have an average of 60MBs Read/write, and the 500G disks have say 70MB/s read/write,
the obviously, 240MB/s (4x60) is a lot better than 210 MB/s (3x70). of course, this is just an example and your disks may be different.


Obviously, do go to the THG Disk charts and check out the disks performance. If the 7200.11 500GB drives trounce the the 320GB disks, then give that consideration.
----------------

Just to give a balance view so you can decide, there are disadvantages however.
-Running with 4 disks vs 3 means a higher chance of failure.
-Having more disks can increase access times of the array. Having said that, if you use a decent RAID controller ($300+) or an Intel ICH8r/9 controller, it will be fine as they are optimized for access times.
-You get less storage

----------------

And just as some final tips,
running a RAID with 3 or 4 disks is getting serious, so I would consider

-Having adequate cooling for your disks
-Staggered spin-up to avoid overloading you PSU
-getting a high quality PSU.
-If using an intel chipset, run a matrix RAID. 32 or 64kbyte stripe size for the OS, and a 128mbyte stripe size for the storage/editing array.

Hopes this helps you
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January 6, 2008 5:59:48 AM

Hi sponge, thanks for the reply.

I will be doing HD capture and editing, so I would think I would need a raid for 4:2:2 720p 60FPS (full uncompressed) to insure no dropped frames. Case is an Antec 900, so the two drives each have one 120mm fan. As for a raid controller, I was just going to use the on-board one on the upcoming x48 motherboard. Don't know much about staggered spin-up. And yes, I'll check the charts out. Thanks for the help.

This is the power supply I was looking at. Should supply the needed power.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
January 6, 2008 6:14:53 AM

Hmmm, Okay

I don't know that much abut HD video so I'll take your word for it. :D 

Antec 900 seems good, plenty of ventilation at with the front grilles. The onboard Intel controller are alright too, they'll be fine. Out of interest, what CPU are you using? Onboard controllers while they are "hardware based" do borrow a few CPU cycles for parity/striping. It's not much - for a 2 Disk RAID0 read/writing at max speed will use around 0.6-3% CPU with a dual core processor (typical usage will be <1%) or even less with a quad core. I'm assuming you would have a decently specc'ed CPU anyway, if your working with HD video (E6600 or better/quad core/AMD equivalent i can't think of...)

The staggered spin-up is a feature of AHCI/RAID. The Intel controllers support it. To enable it, most hard disks have a jumper on the back to set their mode (staggered spin-up, force SATA 1.5gbs, spread spectrum etc). Check the hard disk label for the jumper position or online at their support website.

FYI, staggered spin-up starts the drive consecutively after another, instead of all together when your computer boots up. Hard Disks create a very large surge when they first spin up - up to abt 2.5A each (30W). Especially if you have multiple disks, the initial surge can overload the PSU if they are all attached to the same power rail (12V1, 12V2 etc) Staggered spin-up helps avoid these problems. I can't remember the URL, but Anandtech had a RAID benchmarking article a while back. They had 8 disks running together, and they would have hard disks randomyl drop out of the array, because of power surges/sharing issues.

So yeh, try to enable the staggered spin-up, and keep maybe say half the disks on a separate power rail even if the power supply is quite beefy. 800W should be OK though.
January 6, 2008 6:28:53 AM

Quote:
Windows XP x64 with 8GB of RAM and
RamDisk Plus from www.superspeed.com .

The latter can be used to configure
a 4GB RamDisk with no sweat.

The RamDisk Plus product saves and restores
the contents of each RamDisk between
shutdowns and startups, so you can
automatically archive all data in each RamDisk.

I would add a quality UPS/battery backup unit,
so keep your system running reliably without
unscheduled halts.

RAM has become so cheap,
particularly DDR2-675 and DDR2-800,
system software differences are now
the only reason NOT to expand RAM
above 3GB.


Haha, sound cool. Pity it only supports Windows Server 2000 and 2003.
January 6, 2008 6:31:20 AM

SomeJoe7777 said:
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.


Above is some write specs that you need for HD capture. I'll be using 1080i at 59.94fps and 720p at 59.94fps (both 4:2:2 and full uncompressed).

As for the CPU, I'm waiting for the Q9450... hope it's out soon. Also waiting on the x48 gigabyte ddr2 motherboard. After that, I just need to pick out some ram and a video card. Was going to go with 4x1gb ddr2 800 or 2x2gb ddr2 800 as I hear sometimes when using four ram slots there can be problems. Might also look at ddr2 1200 since x48 supports it.

Do you think this power supply would do the job?
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Thanks flier, I'll look at those drives too.
January 6, 2008 6:52:13 AM

Hmmmm... i remember reading an article that Intel was delaying some CPU's and chipsets to clear old stock, and due to the lack of competition from AMD. Dunno if the Q9450 and X48 are affected though
July 10, 2008 3:52:05 AM

oh my god! I hate this.

The ONLY reason to use RAID is for REDUNDANCY. Raid 0 offers NO redundancy and should be banned and deleted forever.

Go RAID 5 it offers fast hard drive speed AND redundancy.
a b G Storage
July 10, 2008 8:02:26 PM

Raid 5 requires alot of horsepower to get the speed and redundancy from it. I have not seen a onboard controller that can outperform a itself in raid 5 vs. raid 0. For his use i definately do not see a reason to go spending 500 on a dedicated raid controller.

Yes while raid 0 is technically not a raid, it still has it uses. you shouldn't be so elitist concerning raid 0.

I have been running a raid 0 for over a year now with onboard intel and have never had a problem. My pc an record live tv, encode video and play mass effect without skipping a beat so raid 0 has it benefits for sure.

Many reviews show that raid 0 does not scale well beyond 2 drives with onboard controllers. I would do get 2 of the 500GB drives and a third drive to save completed projects.
July 14, 2008 5:52:13 AM

hear hear!

I have 3x 250GB's running in RAID0 for almost a year fine as well (intel onboard ich8r)

With intel controllers though, the sweet spot is 3 hard disks for a RAID 0 array though.
!