Tarjan

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Everything posted by Tarjan

  1. I second Spod's recommendation not to cool the drive below room temperature. Even if you deal with the condensation problem, mechanical HDDs are much less reliable at cold temperatures than at hot. Cold temperatures can cause poor writes for a number of reasons. At cold temps the magnetic fields on the media are more difficult to change. Older and/or cheaper drives do not have "fly height adjustment" of the heads and the write head can be too far away from the media when the drive starts a write. This compounds the difficulty of writing at cold temperature. At Maxtor we tested desktop drives at an ambient temperature of 60 degrees C for thousands of hours. The 1,000,000 hours mean time to failure test was 1000 drives running 1000 hours at 60C, with only 1 failure allowed. The failure rates at cold temperatures were much higher but of course not published. Most drives do not need active cooling unless they are part of a massive disk array. I wonder if LaCie's drive enclosure does not have good circulation and is insulating/cooking the drive in this case.
  2. Tarjan

    Hard drive repair reassembly

    This might be possible for a knowledgeable amateur such as an HDD company employee to do as a novelty project, but getting reliable operation out of the drive after a head/media swap is almost impossible outside a factory setting, even with a clean room. After you swap the heads or platters, the drive will need to re-run the factory optimization and flaw-scanning procedures. If you are not an employee of the HDD manufacturer it will be difficult to gain access to the equipment, software, scripts, and parameters necessary to do these operations on your particular drive model. Without optimizing the drive for the new heads and media, the drive will be extremely unreliable and may not even come ready when you power it on. This is of course assuming you had an exactly identical drive to take parts from. BTW, in the off chance you gained access to some gray market drives (factory rejects) and are trying to repair and sell them: don't bother. The factories already recycle parts as much as they can, e.g. if a drive fails the factory process due to bad heads, they will replace the heads and send the drive through the process again. The drives ending up in the garbage heap really are trash and they are supposed to be destroyed. Trying to refurbish and sell that stuff is unlikely to succeed and is also illegal in most countries. It's theft.
  3. Tarjan

    Question about 'wear and tear'

    If the drive actuator does not use ramp load, spinning down and spinning up the drive will wear out the heads faster than spinning all the time will wear out the bearings. Reason being the drives without ramp load park the heads in a textured landing area on the media when they spin down. While the drive is spinning the head floats above the media, causing little or no wear. I think the bigger concern is heat. Many of the external boxes do not have adequate ventilation, and that will shorten drive life for sure.
  4. Quality of NCQ implementation also varies by drive manufacturer. Maxtor had a pretty good one, but they are unfortunately no longer with us. *sniff*
  5. "Serge, no matter how experienced a person is, nobody lives inside of the hard drive and nobody knows what exactly is happening there. All we can do is _guess_ using our knowledge and experience." This not true. There are many employed in the drive industry who are very good at failure analysis and could tell you exactly what is wrong with the drive. Prior to replacing the heads, he should have measured the amplitude and quality of the signal from the preamp using an oscilloscope... there's no indication he did anything other than "feel" there was a "thermal issue". Replacing the heads is risky and costly, and stupid if it's not going to fix the problem. Different heads are very likely to cause problems, because the drive is not optimized to use heads other than the ones installed at the factory. Hence the "clicking" after the heads were installed, which means the drive can't read the servo patterns any more. This sounds like someone who does not have the necessary equipment or training to perform hardware recovery. I wouldn't pay this guy a dime. Good intuition, Kraak, to question his legitimacy.
  6. Tarjan

    Will WD survive?

    In the short term, I think the merger could be good for WD. Seagate will not get 100% of Maxtor's market share, WD is sure to get a sizeable piece. WD as a company is very lean and mean, and unlike Maxtor they are consistently profitable. It's true they don't spend much on R&D, but that's deliberate so they can maintain financial strength. Why invest in R&D when you can steal components, ideas, and technology from your competitors?
  7. SMART can't predict HDD failure well because many failures (even mechanical failures) are sudden and catastrophic. SMART only helps with gradual failures, such as slow degradation of a magnetic head. You do have a point, though. Funny that my DiamondMax D540X is still alive and kicking after 5 years, and I had to replace my Athlon CPU due to instability.
  8. Tarjan

    Board swap in MaXLine II (300GB)

    There is no difference in PCBA between different capacity sizes of the same model. I think the Maxline II was essentially a "Calypso" model, aka DiamondMax Plus 9. So you might also try swapping PCBA from one of those. There should be a revision # printed somewhere on the PCBA, ideally you'll want those to match. Even with matching PCBAs, there's a chance the boot code flashed on the PCBA doesn't match the drive, in which case the drive might not spin up, or might click on the latch when you apply power. In that case, try another one. Good luck, don't waste too much money on this
  9. Tarjan

    leaderboard not effective

    Performance testing can be done by a trained monkey. Why is it unreasonable to ask for more?
  10. Tarjan

    leaderboard not effective

    Maybe you're right, most manufacturers should be able to pass a compatibility test. Especially since SATA is not new anymore, most of the kinks should be worked out. A few years ago it might have been a better measure of the strength of engineering teams. Just trying to think of some quality measures beyond performance that SR could do. Perhaps some fault injection? - Hack open a SATA cable and short the differential pins while the drive is operating. While doing this, the host could be running a read/write/compare test. That way SR could test the robustness of CRC checking. Might need to make some home-brew hardware to make this deterministic. - Using write long and read commands, test the drive to see how many bytes/sector the drive can correct. - Test performance vs. vibration (varying frequency and amplitude) on a single drive to test mechanical and servo systems. SR would need to invest in some test hardware, for example http://www.labworks-inc.com/ (not sure on pricing for that) Having a large sample size is maybe not so critical for fault injection, since you are testing the design of error recovery mechanisms, rather than evaluating overall reliability of the system.
  11. Tarjan

    leaderboard not effective

    True.As someone in the manufacturing area, though, I don't think a statistically reliable reliability survey is within SR's means or any major hardware review website. Shock/vibration testing is more realistic, but that is also hugely expensive. The testing budget for one product line for one of our customers is over $500,000 a year, just for shock/vibration/thermal, and they are just able to get conclusive reliability data within that budget. Agreed about the reliability testing. It takes hundreds of drives and hundreds of hours to get meaningful results. And then you need engineers to accurately diagnose the failures to see if they were the fault of the drive, the test-bed hardware, the test software, the user, etc. But, maybe SR could add something beyond performance, such as a compatibility test? Get maybe 20 motherboards and/or drive controllers with different chipsets, and see if each drive+controller combination passes a basic functional test of an hour or so. Good compatibility might be indicative of how hard the HDD manufacturer works to iron out problems...
  12. Servo system adapts to vertical orientation just fine. Multiple-drive-interaction vibration issues happen just as easily with the drives in a horizontal position. Quality of the drive bays are of bigger concern here. Bolt 'em down to solid metal. I imagine customer reps probably recommend horizontal positioning because that's how most of the reliability testing gets done: http://www.flexstar.com/products/index.htm
  13. I wrote, a drive "which was wiped", meaning completely overwritten with data. The method of retrieving "magnetic traces of the previous states" is what I was referring to. Considering the number of bits to process in a modern drive, the expensive equipment, expertise, and labor needed, that method is prohibitively difficult. Worrying about it is silly.
  14. You guys are so paranoid. Retrieving data from a modern HDD drive which was wiped is difficult to the point of being practically impossible. You would need resources on the order of $millions. No-one is going to go through that to get credit card accounts or see if you were downloading p0rn, etc.
  15. Tarjan

    Seagate 7200.10 Review

    I have a question on this drive, maybe StorageReview can find out for us: Per Seagates info sheet (http://www.seagate.com/docs/pdf/marketing/po_barracuda_7200_10.pdf), the perpendicular recording method used by the 7200.10 helps decrease moving parts. Fewer moving parts relative to what, the previous Barracuda or the competition? Does this mean that by using perpendicular recording, the 7200.10 does not need to use a micro-actuator? The 7200.10 uses Adaptive Fly Height, so one would think that the 7200.10 would have an increase in moving parts relative to previous generations.
  16. Tarjan

    Strange sound on Diamondmax 10

    Return the drive. Delayed Write Failed is very serious, it means the drive not only could not write to the target area, but also the drive could not write to the spare sector location(s). It's probably better to avoid Maxtor these days. Their factories are all but shut down, the engineers are not working while waiting for their fate to be decided. Who knows what junk is getting shipped?
  17. Tarjan

    Strange sound on Diamondmax 10

    Try turning off SMART. SMART sometimes does annoying and useless tests in the background when the drive is idle.
  18. Tarjan

    Long IDE cable

    Matching SATA controller to the adapter manufacturer is a good idea to avoid compatibility problems. I'd go for a Highpoint 1640, they run about $90: http://www.highpoint-tech.com/USA/rr1640.htm It's a RAID card, but you can set it up as JBOD. They have FreeBSD drivers, not sure if that's compatible with NetBSD? Considering your OS you might need to roll your own S/W for testing. Just make sure you tag each 512 byte block with the unique LBA# for the read/compare.
  19. Who is your vendor? You might have bought gray market product. Sometimes drives which fail reliability tests in the factory and which are supposed to be destroyed mysteriously end up for sale somewhere instead If the factory did a retest on a drive and intended to sell it later, they would wipe the SMART data afterward so the customer would not see this.
  20. Tarjan

    Long IDE cable

    My experience with 36" ribbon cables is we used them to generate CRC errors on the PATA interface during UDMA/100 fault injection testing. PATA cables are spec'ed at 18", for good reason. Since PATA uses such an archaic electrical interface (5V TTL), the signal timing can get screwed up over longer distances. And because PATA does not have CRC-protection over all operations, there's a good chance you can corrupt data on the drive using a non-spec cable. If you really need a long PATA cable and there is no way around it, you might want to limit your transfer rate to UDMA/66 or even UDMA/33. That will reduce the chance of errors. If you need performance, reliability, and long cables, better just bite the bullet and go SATA or SCSI. You might try PATA/SATA adapters if you are on a budget and have a lot of old PATA drives. Then you can use a 1 meter SATA cable without worries about questionable engineering: http://www.highpoint-tech.com/original/USA/rh100.htm Highpoint is pretty good with SATA compatibility. I think these run about $25, maybe less if you buy in bulk.
  21. Tarjan

    Audi to field diesel at Le Mans

    Diesel passenger cars in the US are pretty limited. It'd be nice if we had more options, something beyond 2.0L displacement, and something beyond the VW Golf and Jetta.
  22. Tarjan

    Airborne Laser Missile Defense

    Seems enemies could just use a low-flying cruise missile (like a Tomahawk) on a cloudy day. Wouldn't clouds dissipate laser energy pretty quick? Maybe they are using microwaves (a MASER) instead? Microwaves have much better cloud penetration than the visible spectrum.
  23. Tarjan

    Overwriting a drive

    If you write a drive with 0s, the data passes through an ECC engine and gets further encoded after that. So it looks nothing like 0s on the media. There's no difference from using random data. The way to get around this is to meticulously go bit-by-bit with an oscilloscope, and determine the original pattern written. Then, perform a "direct write" to the media with the original pattern, bypassing the ECC engine and encoder. Then you could read the data out from the drive normally. To perform a "direct write" you would need cooperation from the drive manufacturer to provide the proprietary command interface. A good 5 GHz oscilloscope can cost over $100K. Cooperation from drive manufacturers is not free, and engineers who can do this kind of thing are rare and not cheap. Considering the enormous size of drives, whoever did this would also need to develop equipment to read data from the oscilloscope and do the bit analysis automatically. Further design+development cost (on order of $millions). Point is, recovery of a wiped drive would cost way more than a few thousand $, and without guaranteed success. I doubt anyone would undertake a project like this unless it was a matter of national security.
  24. The SCSI drives designed by Maxtor's Shrewsbury group used to be manufactured in a robotic factory run by MKE in Japan. These days the SCSI drives are assembled by Maxtors own semi-automated factory, I think the one in Singapore. Many of the parts are outsourced. ---------- The reason Seagate and Maxtor won't make a Raptor competitor is because they don't want to convert customers who would otherwise buy a high profit margin SCSI product. ---------- I don't see much price erosion on SCSI products. Probably Maxtor's SCSI volume is not large enough compared to demand. Seagate might be pressuring Maxtor to reduce SCSI volumes right now, because they don't want to flood the market with cheap SCSI units; that would reduce profit margin on Seagate's own SCSI products. I doubt you will see cheap SCSI drives from the merger.
  25. Using an "elastic suspension", rubber grommets, or a plastic drive bay etc. can make the drive self-excite, i.e. the drive can start to oscillate due to movement of the spindle and actuator. Not so good for performance or reliability. Wizard's solution is a good one: "Best solution is find heavy thick metal plate and attach each HD to this via four screws to try to damp out low frequency vibration."