HDD vibration solution

darkseid · 03-23-2006, 05:08 PM

I`ve spent the last 2 hrs searching the forums. A while ago there was a post with a blue 3.5" external HDD enclosure with silicon damping built in. Anyone help me out finding it again. The reasonI am asking is I have designed a Carputer with surveilance built in (upto 16 channels of realtime h264 video encoding) designed for a toushscreen interface and would like to have a 3.5" storage soltuion as opposed to a 2.5" storage solution.

greenman100 · 03-23-2006, 05:13 PM

oh man

NO ONE

I repeat

NO ONE

has ever had a HDD fail from vibration in a car

people have gotten into major car accidents with teh carputer on and the HDD is fine

darkseid · 03-23-2006, 05:23 PM

Yeah but my application is really for the transport industry (buses and coaches) and I have seen lots of drives fail in that environment (my last job was with one of the UK`s largest installers of in vehicle CCTV)

TruckinMP3 · 03-23-2006, 05:35 PM

Ahhhh BS.

As a user of an in Car 3.5 HD for 9 years and several car crashes with the HD in use.

phatmonky · 03-23-2006, 11:09 PM

Don't listen to these guys

You're putting a commercial product out. You need to at the minimum put on a good show (no matter one's opinion on whether a certain environment variable affects longevity)

http://froogle.google.com/froogle?hl...ch&sa=N&tab=wf
Hope that helps some. I never saw the post you are looking for.

piabu · 03-23-2006, 11:19 PM

The short version:
Modern HDDs (especially 2.5") are engineering to withstand tolerances beyond the human body. The HDD would survive conditions that would kill you.

The long version:
<you have to ask somebody else..>

My opinion:
Is the cost of damping in every install lower than the cost of replacing failed drives (assuming you can estimate the failure rate)? Alternatively would it be cheaper to built redundancy (RAID?) into the system?

Let the flames begin..

quantum · 03-24-2006, 12:01 AM

Quote: Originally Posted by TruckinMP3

Ahhhh BS.

As a user of an in Car 3.5 HD for 9 years and several car crashes with the HD in use.

Hmmm, car PC = several car crashes... I'd better call my insurance company and raise my policy limits before I start my install!

PCModifiers · 03-24-2006, 12:04 AM

I hope all these car crashes you guys are having aren't due to having a computer in your car

Arathranar · 03-24-2006, 12:19 AM

Given that the 2.5" drives are supposed to be more shock resistant, they sure fail often enough. I have one laptop that is on it's 3rd drive. My car PC is still going strong with it's 3.5" drive over the same time period.

I mounted it to the top of the case using rubber grommits in the mounting holes to give it some vibration isolation. Mostly I did it for the noise reduction though.

scott_fx · 03-24-2006, 01:04 AM

my 3.5" is solidly mounted horizontally in my car with sport suspension and rubber bands for tires. not a problem yet.

darkseid · 03-24-2006, 03:22 AM

Its actually not the shock that kilss the HDD as they are built to withstand large amounts of shock for a short time (for instance the speck for operating shock for hitachi 250GB drives is 55G for upto 2ms) however vibration is the killer as the operating values for the same drive are 0.67 horizontal and 0.56G vertical. Typical values for 2.5" drives are around 300G for shock but the vibration spec is the same at 0.67G (http://www.hitachigst.com/hdd/support/4k40/4k40.htm).

In my previous job we fitted systems using 3.5" and 2.5" HDD`s and to be honest (the kit had vibration isolation) the amount of failures for 2.5 and 3.5 where about the same.

Thanks for the link Phatmonky.

tallman · 03-24-2006, 03:34 AM

i had an old cd box for kenwood headunite i remove the anti-vibration from it and but it in the hardisk ... i didnt use it until now because the motherboard has been burn but i think is a good idea

sama · 03-24-2006, 05:01 AM

presumably, you will be doing a hell of a lot of writes too in a video recording environment. that's a very different story to reading. whilst drives can be reading and get jolted, they just have to go back to the begining of the disk and seek again. reading is not destructive.

whilst taking precautions with your hardware is a good measure to stay within the limits of the operating values, you need to focus on the configuration and software more than anything.

If you're writing and the head jumps, then congratulations, you've just spilt your paint all over your mastepiece. And the damage caused can vary from corrupt files, to corrupt and irreprable disk. It's not as simple a matter for writing as it is for reading. In such a case, it won't matter what hardware precautions you've taken, as the HD will be a gonner.

Here are some ideas. Of course I'm not considering cost here, so some shorcuts may need to be take.

1. completely seperate the operating system from the recording medium. It's probaby best to embed the OS on a CF card so that you completely illiminate HD failiure affecting the OS. This is essential for the ability of your software to recover from failiures.

2. set up a raid array with delayed mirroring so that the first disk writes whilst the second waits. After some time, the second mirrors the first. In that configuration, should the first disk fail, then the second disk will already have the last snapshot before the first one died, and it won't continue to mirror since it can't read from the first. You could add more disks and have a very complicated writing mechanism, but that depends on how many times your devices will fail. You need statistics to acccurately get those figures and some research into the best RAID configuration. Did I mention the testing you'll need on those algorithms?

3. you could use tape for recording. will you be doing any processing on the video stream? if not, then you could multiplex the channels into a single channel and record them to digital tape. Again, need to know what the minimum resolution required is etc. Tape is risk free from vibration and you may get away with using a cheapo DV cam with DV-in to record the stream. Everytime the tape gets full, you dump it to disk.

There are solutions out there, like this one to spot just one of the millions out there. But I'm not sure what you're doing! what are you trying to do exactly?

The sky is not the limit if your money is infinite!

Arathranar · 03-24-2006, 05:06 AM

2 sounds pretty complicated. Wouldn't a standard raid 5 setup be simpler and allow you to detect and replace dead drives without losing any data.

darkseid · 03-24-2006, 05:10 AM

I agree with you. Alot of people think that because their HDD hasnt failed then the install is OK. But what they need to realise is that in general a CARPUTER is reading relativly small amounts of data into memory (mp3 files at 3-4MB a piece and satnav data) and the chances of the HDD taking a big enough knock for the head to collide witht he platter are slim. However in my app we are writing to the disk for upto 20Hrs at a time (this is another reason I want to use 3.5" disks as they have a larger duty cycle than 2.5" disks). I have the OS embedded on DOM and the recording medium is seperate using a custom disk structure. In mobile video apps the biggest problem tends to be the index files getting corrupt (many writes to index all of the available video footage), however we have designed the system so it writes a video file opens the index to log the start time, closes the index then reopens when it moves onto the next file. Also the backoffice client software can recreate the index files from scratch as long as the video data is valid. Using a raid as backup is not an option as space is at a premium (also the market its aimed at is price sensitive).