Mixing HDDs of different RPM?

[jackfalbey]

I'm beginning research for my next system, and I've got a question...

I've read that all the HDDs in a case should be the same RPM or else the differences in rotational vibration can cause read/write errors. I've also read recommendations to have the OS on a 10k or 15k drive, and use 7200RPM drives in a RAID for video. Does anyone have any thoughts or insight into this issue?

[Gooder]

I would only use speeds no less than 7200RPM for video work!
I can't think why I would opt for a drive that has a slower speed, just my opnion

I'm sure the experts will be along shortly

Cheers,
Lee

[John 'twosheds' McDonald]

My system has three discs at present.

WD Raptor as C: drive (10,000 rpm, 150Gb) holding OS and programs only (plus any Windows allocated workfiles)
WD SATA II as D: drive (7,200 rpm, 250Gb) holding all of my data (documents, personal stuff, etc.)
WD SATA II as E: drive (7,200 rpm, 500Gb) as video work disc and finished DVD archive (not project archive).

I have not heard of the rotational vibration problem before but I can state that I have no problems whatsoever with these drives; no vibration, no conflict.

HTH

[Bob]

Hi Jack,

You want thought, I'll give you thoughts...

RE: mixed rotation speeds. I wouldn't worry about it. While it's true that a rotating disk vibrates and includes regular and random components to that vibration, that would be true whenever you have more than one disk regardless of rotation speed -- mixed or not. Do they also advise only using one disk drive? Didn't think so. Damping is excellant in modern drives and I don't feel it's an issue. If you have a link to that item you read on this, I would like to see it. It's usually a good idea to match speeds if the drives are configured as part of a raid array, but that's for performance reasons, not reliability.

RE:10k drives for OS. That's not a bad idea. There is a lot of activity on the system drive and a faster drive will generally have lower latency, lower seek time, and a potentially higher transfer rate. The type of activity on the system drive is heavy in random access seeks which are much slower than the track to track sequential seeks that typically occur on data oriented disks. A faster rotating drive has a real advantage on a disk with lots of random accesses.

RE: Raid for Video. You see a lot of people using RAID 0 setups for video. The idea is that Raid 0 writes to multiple disks concurrantly increasing the data throughput bandwidth substantially. That's true, but the tradeoff is that you are increasing your bandwidth but decreasing your reliablity. Raid 0 arrays are not striped with parity and they do not implement error checking -- any error is unrecoverable. Raid 0 made a significant difference when the typical drive speed was 3200 rpm, but I'm not convinced that raid 0 is really necessary for ordinary video editing applications anymore given the current drive speeds and SATA transfer rates. It would be interesting to see a comparison of raid 0 vs non-raid for projects of typical complexity. I would definitely use no slower than 7200 rpm (preferably SATA) for my video drives.

Just my opinion.

[Chuck Engels]

I thought about getting 10K drives for my Precision but decided against it mainly due to cost.
I also have not seen any reports of huge improvements in performance over the 7200rpm drives.
On servers the 10k and 15k drives can make a huge difference, but on a stand alone workstation, not so much.

When I received my new Dell Precision it had RAID 1 already installed and set up.
I have left it and when I added my new 750gb drive it is not part of the RAID setup.
So I have mirrored Primary Drives (2) and a 3rd internal that is not RAID controlled.
This has worked find and I have had no problems, editing or capturing so far.
I do have a slowdown on occasion that lasts for a second or two, that could be due to the mirror setup.
It would take more time that it's worth to change the RAID setup right now so I will leave it alone for now.

[jackfalbey]

Thanks for all the feedback, guys!

I definitely would not use anything less than 7200RPM, and will most likely continue using a RAID0 or 5 for the video drive, since it has worked very well in my Dimension 8400. The main reason I asked is that I'm seeing some good deals on Precision Workstations in the Dell Outlet with single-Quad and dual-Quad-core CPUs but many of them come with 10k or 15k system drives, and I was concerned about mixing those with a 1.5TB 7200RPM RAID that I would add myself.

As far as where I read about the rotational conflicts, I think it was Harm Millaard on the dvinfo forum, but I read a bunch of different stuff that day and I'd hate to put words in his mouth...

[Ken Jarstad]

I remember John crowing about the performance of his Raptor drive. Sounds like it would be worthwhile for video editing. Can't understand why anyone would want to mess with RAID though. CPU Magazine, which caters mainly to gamers, did a performance evaluation of RAID vs non-RAID systems and found that RAID has little or no performance benefit these days.

[Bobby]

I have not done any analysis here of RAID configurations as I don't want to mess up my system reconfiguring it! But I have had two SATA drives in RAID 0 on this PC, now 4 years old with zero failures. Of course, I have lots of backups just in case though!

But any of the system performance tools I have run show an increase in performance with the SATA RAID array over a single internal PATA drive (used for backup). Now before you get honked off on that difference, there is really no performance difference between SATA and PATA for hard drives - the drive mechanicals are the limiting factor for large files.

Anyhow, the RAID array ran tests in about 75% of the time that the single drive did. Not double the speed, but a definite improvement.

My next system will have RAID 0 10,000 rpm drives.

Bob

[John 'twosheds' McDonald]

I remember John crowing about the performance of his Raptor drive.

Didn't think I was crowing, Ken. I thought that I had fairly reported the 'real world' speed increase the Raptor had given.

[Chuck Engels]

Oh, go ahead and crow John

[jeffterm]

Geek talk, I just couldn't pass us:

10k drive for your OS will have your system operating faster.
RAID for speed does not really show up in real world applications. For Video systems, I feel a RAID mirror for reliability, would be more to your advantage.
Note: this does NOT replace an off system backup routine - just suppliments it.
NO reason not to buy 7.2k drive for all other drives.

Remember: The only way you would probably 'notice' the speed difference between the components would be to have two of them sitting side by side - you will become accostumed to the speed of the unit you sit in front of everyday, and not even notice as it slows down over time due to bit-rot. But when fresh and new, It will rock like no other editing system you've ever had. (Thats the new system feeling I love so much!) - You guys are making me want to go to Fry's

Read all the info you can find on your RAID controller as well. Part of my MB decision was because it had a SATA RAID built in, only to find feedback that it operated slower than what it should, and had conflicts with the other onboard controller. It was recommended to still buy a PCIx1 RAID card for best performance. [Again - I'm not going for performance, as much as mirror - so I didn't] - but read up on your hardware.
All these drives is also why you want to drop an extra bill on the PSU!

I wonder how late Fry's is open until tonight?

[Ken Jarstad]

Hey John, when you first described the experience with your new Raptor I thought you were really "stoked" Put that in your English - American translator! Wikipedia actually does a pretty good job.

Just in case there is any misunderstanding between us English speakers, I was impressed with your first report about the Raptor and I was certainly glad you shared it with us. Here, on the "left" coast of the USA near Seattle, that is something really worth "crowing about"

[John 'twosheds' McDonald]

Thanks Ken. I suspect that it was just my natural modesty coming through.

[jackfalbey]

RAID for speed does not really show up in real world applications

Dealing with DV and HDV data rates (3.1 MB/sec) I agree completely, but eventually I plan to get better cameras and will need much higher throughput to handle 10-bit 4:2:2 video streams captured live through HD-SDI. A RAID for speed will definitely make a difference there. My own personal testing with HDTune got these averaged data rate results:

Laptop
C: drive (Hitachi 200GB, 7200, 8MB) ------------ 51 MB/sec
eSATA external (WD 500GB, 7200, 16MB) ------ 65 MB/sec

Desktop
C: drive (WD 250GB, 7200, 16MB) --------------- 49 MB/sec
RAID0 (Seagate 2x160GB, 7200, 8MB) -----------85 MB/sec (55 MB/sec in non-RAID)
backup (Samsung 750GB, 7200, 32MB) ----------74 MB/s
USB external (WD 500GB, 7200, 16MB) ----------21 MB/sec

So, it appears that the RAID0 gives a 1.55x speed boost in my particular situation...
Also, the current desktop's mobo is only SATA 1.5, so I'm assuming that a new PC at SATA 3.0 with 2 Samsung HD753LJs in RAID0 ought to give well above 100 MB/sec throughput, which will come in handy for pro-level HD codecs.

And just to clarify my original question that started this thread... you all agree that there's no problem with having 10k or 15k drives in the same chassis with 7200s?

[hpharley90]

And just to clarify my original question that started this thread... you all agree that there's no problem with having 10k or 15k drives in the same chassis with 7200s?

I have been just following this thread and it seems the consensus is no problem.