HDD vibration solution - Page 2

sama · 03-24-2006, 05:56 AM

Quote: Originally Posted by Arathranar

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.

I agree that using industry standard is a must. and that there's no need for complications! I thought there is a need here to minimise the writes, due to the constant streaming, as well as writing in a reliable fashion. I was talking about using a RAID array, in addition to some software that mananges buffering and writes to disk. I probably didn't convey that very well. but in any case, it seems that darkseid already has a special writing strategy in place to ensure the video stream is kept.

Quote: Originally Posted by darkseid

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).

great! so I understand that your config and software have already evolved to the point where the concern in your design is the hd mounting. So I will try to help there if I can.

how about using foam flooring with the hd on top? you could then use a spring loaded screw to mount the hd on. I read this in another post on here. it's cheap, it's durable, and you usually get it for free when you buy a disk

just out of nosey interest

what form factor are you using? an x86 PC104 or simlar or ITX?

darkseid · 03-24-2006, 06:31 AM

Thanks for the input and interest Sama. To satiate your curiosity I am currently using MS1200 and SP1300 boards from Via, and the capture technology is from a chinese company I have been working with for the last 3 years (you wanna see the compression tech these guys have, I can compress in realtime in hardware upto 16 channels of video utilizing only one PCI slot at 25/30 FPS). I have some development PC104 parts from them but am using a known quantity first (lets be honest how many via mobo`s are running around in cars world wide without issue). The problem with the foam mounting is I would really like something off the shelf as the storage has to be removable (the end game is to shunt the recorded data wirelessly however convincing the customer to spend upto 300K in infrastructure ain easy) so they can process the images and thus has to look professional. If I can use off the shelf it saves on metal prototyping. However I will be recieveing some antivibration dampers for HDD`s tomorrow and will lokk at producing a bespoke external enclosure. On a side note are you freelance or a gainfully employed programmer???

sama · 03-24-2006, 08:04 AM

ah, you're the guy that advised me a while back on the flexi pci card stuff! I knew your nick ringed a bell!

nice. I'm a contractor, currently for siemens and will be at AOL next month. I have a history in computer vision research hence my interest. I've been very keen in doing something on the car pc with cameras. Passive radar to be precise.

I'd be interested in doing some freelance work if you need some done. Where are you based?

darkseid · 03-24-2006, 08:47 AM

I`m based in the North East of England, however most of my business is in the South. My software engineer is based in Kingston, however I will be needing somebody else in the future (I have a million ideas for allsorts of funky stuff, remote tracking, live video to PDA,mobile phone (can already do this just need to speed up the frmae rates). I have 5 years in the digital surveillance industry as a hardware integrator and this is my first solo project. You will have seen some of my work if you travel by bus in London.

konnichiwa · 03-24-2006, 09:17 AM

I bet next you'll be installing speed cameras in buses so you can rip us off on the move!!

sama · 03-24-2006, 09:30 AM

chances are I'll know who your s/w engineer is, espeically if he's a kingston uni student!

darkseid · 03-24-2006, 10:24 AM

They already install bus lane enforcement cameras on buses in london. To install spped cameras in buses would be an real engineering challenge to process speeds accuratly from a moving platform to another vehcile moving towards or away from that platform. Sama I doubt that you would know my SE as he isnt a kingston uni graduate he just chose kingston to live there. His name is Chris Cowley he hadnt done anything inthe video field up until I met him 2.5 yrs ago and we have developed 3 products together for other companies. We now are having a crack out our own thing.

TruckinMP3 · 03-24-2006, 04:48 PM

Quote: Originally Posted by darkseid

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.

If Vibration kills them so fast why does mine still work?

It has been in 3 trucks for over 250K miles.

sama · 03-24-2006, 05:53 PM

I would suspect it's 'cos you have not been writing for 250k!

DaveTN · 03-24-2006, 05:55 PM

Darkdeid,

I actually have something like what you are talking about. I used it as my first carpc. It is called a Siemens Simatic Box-PC. It is based on a NLX motherbaord with a pci card riser and an intel mobile CPU. The HDD is mounted in a box that is vibration isolated with oil filled mounts on each corner. Each mount is the size of a marble and does quite a good job of shock mounting. I just recently sold one of the PC's but kept the other one for future use. I obtained them from a company that was using them in small airport kiosks and expected them to be kicked a time or two.

Uh Uh Uh, You didn't say the magic word !

I got them when they were "decommissioned". One of the boxes that they came in had an invoice indicating htat the original cost was $10,000.00 each!! I'd say I got a bargain.

David

darkseid · 03-25-2006, 04:23 AM

Dont suppose you could take a picture of one of the mounts for me

bland · 03-25-2006, 09:01 AM

I surprised no one mentioned it yet. Search for solid state HDD. They are hard drives that use memory (Like ram) instead of a spinning disk. So shock is not a problem at all.

The down side is the price and the storage capacity is less.

http://www.m-sys.com/site/en-US/Prod...TASelGuide.htm

darkseid · 03-25-2006, 09:23 AM

I am using solid statefor the OS, however in a write intensive application like a DVR using solid state as the recording medium is not an option as they are still limited to write/erase cycles (around 2M write/erase cycles for normal SS memory and 5M in the case of the M systems stuff) which would mean the disk would need replaceing after around 6 mths of use (the whole disk would be over written every 8 - 10 days. And the cost is ridiculous, I looked at 30GB solid state modules around 6 months ago and they where priced at 3K GBP

TruckinMP3 · 03-25-2006, 10:08 AM

Solid State is an expensive solution for a problem that can be solved with Desktop drives.

SnyperBob · 03-25-2006, 10:24 AM

Just an FYI - I've had two (new) desktop hard drives fail within the past three years due to vibration in my car.

Based on the design of my case, I had to mount my drives horizontally. Obviously this isn't the best solution, but I figured harddrives are cheap enough, that I don't mind replacing them when they die.

Now, for those of you that haven't had hard drive problems - are any of yours mounted horizontally? Also, are you guys driving nice cars with smooth suspension? My car (obviously) doesn't have much of anything for shocks.

Most of the modern cars are so smooth, you could practically have an open beverage full to the brim and not spill it (figuratively speaking, compared to my car). My guess is that public transportation won't have the luxuries of a nice sedan/sports car....