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#1
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Failure of external HDD's - why doesn't any manufacturer wake up to this?
A couple of years ago I bought 4 external HDD's, Maxtors, to increase
storage capacity on some machines (and offer portability) in my business. After 2 failed in short order I returned the other 2 and swore not to touch external drives again. A couple of months ago my IT supplier convinced me to try a Lacie 2T external HDD (internally, 4 Hitachi 500G's in a raid 0 array). We were using it to store video clips after editing, pending backup to tape. Sure enough, it has failed and I am again in the quandry of whether to send it back for warranty repair - risking propagation of my sensitive files, and the best I can hope for, is a new, empty drive. Recovering the data is at least $3,500 and I may not get it all. The drive itself cost me $2K. ($Australian). I'm an engineer and it is my opinion that these units are all under-designed, thermally. Ok they have cooling fans but that means nothing. In the case of the Maxtor units, the HDD was suspended internally on rubber bushes and so there's no mechanical heatsinking. A one-inch fan sucked out a little warm air but the drive itself still ran hotter than one mounted inside a PC, where the chassis sucks up a fair amount of heat. One type I looked at didn't even have cooling fans so the casing was effectively a blanket! The Lacie drive had been left on (but mostly idle) almost continuously for the entire 3 months it was in service, and failed during a cold start. That smacks of a thermal stress failure. These days I always order my PC's with cooling fans mounted directly on the HDD bay and haven't had a failure since. Put your finger near the spindle of a HDD that has been running an hour or so and you'll find it almost too hot to touch. Friction rises exponentially with temperature because it's a positive feedback loop. Heat loss also rises exponentially with temp, which stabilises at a point where they are in balance - and the better the heat removal, the lower the temp. HDD failure is every computer user's worst nightmare. The temperature issues are obvious to even a novice engineer. So why, oh why, do they continue to underdesign these things - not just in external units, but inside PC's as well? Of course both manufacturers told me "you know we dont' get many of these back..." (Probably something to do with their policy that the faulty unit can't be returned and therefore you have no hope of getting your data back, so you're better off sending it to a data recovery service). Who else has experienced a higher failure rate on external HHD's? Or undercooled internals? As far as I can tell my only solution for reliable, portable mass storage will be to re-engineer a commercial unit to improve it's cooling - but void its warranty. Who cares, the warranty is useless when it doesn't cover your data. |
#2
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Failure of external HDD's - why doesn't any manufacturer wakeup to this?
richard wrote:
.... HDD failure is every computer user's worst nightmare. The temperature issues are obvious to even a novice engineer. So why, oh why, do they continue to underdesign these things - not just in external units, but inside PC's as well? The disk manufacturers, at least, don't: the environment for which their disks are designed is quite publicly specified, and it's hardly their fault if those who use the disks don't pay attention to it. Failure rates of (S)ATA units have been studied by users as well as manufacturers: while the real-world-environment failure rates encountered by the former (such as the Internet Archive project and the - I'm sad to say now apparently late - Jim Gray at Microsoft) tend to be higher than the more-carefully-controlled-environment failure rates published by the latter, the differences aren't nearly sufficient to support your allegation that they're 'underdesigned' for their use. Perhaps you're just unlucky, or unusually hard on your disks, or the design of the cases you use sucks, or you're using older disks (the newer ones don't tend to get nearly as hot as you claim when properly cooled: for the past several years my internal 7200 rpm Seagates have idled at around 20 degrees C. below their nominal 55 degree C. maximum, according to S.M.A.R.T., with no special cooling arrangements such as you describe: the normal influx of air to the front of the drive bays caused by the PSU fan plus a single auxiliary 80mm. fan is more than sufficient for them). Unless the internal air flow misses the drives, you can get a pretty good idea of how hot disks in external cases are getting by checking whether the exhaust-fan air feels warm (if not, the flow is probably adequate to keep the disks cool). You noted that one of your external cases didn't have a fan, and just acted as a 'blanket'. Maybe, maybe not: some such cases claim to make good thermal contact with the drive and conduct heat efficiently to their exteriors (the USB example that I happen to have here unfortunately doesn't report S.M.A.R.T. attributes via any of the software I have readily available - anyone know of some software that might do this?). In any event, don't presume to generalize from your own experience - especially given the ease with which you could find broader relevant information. .... Who else has experienced a higher failure rate on external HHD's? Or undercooled internals? Undercooled disks certainly don't live as long - the rule of thumb is that the life halves for every 15 degree C. rise in operating temperature (and likely drops far faster if you exceed the nominal maximum). Of course, external drives may also be prone to more physical shock during operation than internal drives. The bottom line is, keep your disks reasonably cool and free from abuse and they won't disappoint you. As far as I can tell my only solution for reliable, portable mass storage will be to re-engineer a commercial unit to improve it's cooling - but void its warranty. Why not just look around until you find a commercial unit that cools its disks properly? With external SATA units that should be trivial (no problem getting the S.M.A.R.T. information there). - bill |
#3
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Failure of external HDD's - why doesn't any manufacturer wakeup to this?
In article vpadnVkUKdnZskvYnZ2dnUVZ_uejnZ2d@metrocastcablevi sion.com,
Bill Todd wrote: richard wrote: ... HDD failure is every computer user's worst nightmare. The temperature issues are obvious to even a novice engineer. So why, oh why, do they continue to underdesign these things - not just in external units, but inside PC's as well? The disk manufacturers, at least, don't: the environment for which their disks are designed is quite publicly specified, and it's hardly their fault if those who use the disks don't pay attention to it. Failure rates of (S)ATA units have been studied by users as well as manufacturers. Both large scale users (computer and storage array makers) and disk makers have very detailed data on this. However, this data is not shared with competitors, nor with consumers. Several studies have been published in the open literatu while the real-world-environment failure rates encountered by the former (such as the Internet Archive project and the - I'm sad to say now apparently late - Jim Gray at Microsoft) May Jim rest in peace. I hope he died the way he wanted to. At this point, that's the best we can hope for. In addition to his data, this year's FAST conference (go to www.usenet.org and search for FAST2007) had two papers on real-world disk failure rates. The first one (by Bianca S. from Carnegie Mellon) got best paper award, and has a lot of information about a variety of settings. The second one (from google) has some very interesting information about a 5-year study; unfortunately, it mixes older and newer disks. The second paper has some astonishing data: namely that disks live longer if you don't keep them too cold; 30 or 40 degrees are better than 15 or 20. We know that really cold temperatures (5 or 10 degrees) are bad for disks, but I was quite astonished by this result. A very senior person from a disk manufacturer was sitting next to me during this talk, and was shaking his head. The above observation quite bady violates many things we thought we had known, and might be an artifact of mixing different disks that use different housings in the same data set. So don't take it too serious yet. Please note that disk lifetime is also affected by other factors. Such as workload: continuously seeking is bad; continuously writing is also bad (as it increases the risk of off-track writes). This is particularly true for consumer-grade disks (which is often but no always synonymous with IDE/SATA disks); those are typically specified for 40-hour-per week operation, instead of 24x7. Disk lifetime (and error rate) is obviously affected by temperature, except that the recent Google result above confuses that issue. It is also seriously affected by vibration, in particular for consumer-grade disks (again, often IDE/SATA), which can't simultaneously servo and transfer data. For this reason, it is important to use vibration-absorbing disk mounts, low-vibration fans, and isolate disks from other vibrating components (such as CD-ROMs and other disks). Mechanical shock during operation can be very very bad, so don't kick your computer just because your program doesn't compile. Perhaps you're just unlucky, or unusually hard on your disks, or the design of the cases you use sucks, or you're using older disks (the newer ones don't tend to get nearly as hot as you claim when properly cooled: for the past several years my internal 7200 rpm Seagates have idled at around 20 degrees C. below their nominal 55 degree C. maximum, according to S.M.A.R.T., with no special cooling arrangements such as you describe: the normal influx of air to the front of the drive bays caused by the PSU fan plus a single auxiliary 80mm. fan is more than sufficient for them). Warning: 10K and 15K RPM SCSI/SAS/FC disks run considerably hotter than 5400 and 7200 RPM IDE/SATA disks. Particularly true for 2.5" enterprise-grade disks. All those disks should be equipped with a fan that guarantees good airflow. In any event, don't presume to generalize from your own experience - especially given the ease with which you could find broader relevant information. If you want to generalize from your experience, your experience better be based on hundreds of thousands of disks. Most home computer users (fortunately) don't gather that kind of data. -- The address in the header is invalid for obvious reasons. Please reconstruct the address from the information below (look for _). Ralph Becker-Szendy |
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Failure of external HDD's - why doesn't any manufacturer wakeup to this?
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#6
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Failure of external HDD's - why doesn't any manufacturer wake up to this?
On Feb 16, 11:27 pm, wrote:
In article vpadnVkUKdnZskvYnZ2dnUVZ_uejn...@metrocastcablevi sion.com, Bill Todd wrote: richard wrote: ... HDD failure is every computer user's worst nightmare. The temperature issues are obvious to even a novice engineer. So why, oh why, do they continue to underdesign these things - not just in external units, but inside PC's as well? ... In any event, don't presume to generalize from your own experience - especially given the ease with which you could find broader relevant information. If you want to generalize from your experience, your experience better be based on hundreds of thousands of disks. Most home computer users (fortunately) don't gather that kind of data. Richard's observation that common-or-garden external enclosures are underdesigned is likely quite valid. Although one should perhaps spend commensurately with the value of one's data, not just on enclosure, but also on redundancy. It's also usually true that software could make better use of SMART data and other early warning signs (I believe this is on Solaris' ZFS and Fault Management roadmap). http://www.opensolaris.org/os/community/fm/ http://blogs.sun.com/eschrock/date/20051121 -- The address in the header is invalid for obvious reasons. Please reconstruct the address from the information below (look for _). Ralph Becker-Szendy |
#7
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Failure of external HDD's - why doesn't any manufacturer wakeup to this?
richard wrote:
In article vpadnVkUKdnZskvYnZ2dnUVZ_uejnZ2d@metrocastcablevi sion.com, opined thusly: Unless the internal air flow misses the drives, you can get a pretty good idea of how hot disks in external cases are getting by checking whether the exhaust-fan air feels warm (if not, the flow is probably adequate to keep the disks cool). Without voiding the warranty how can you know? If the air is cool it is either missing the drive or doing a good job. If the air is warm Actually, the air shouldn't be more than luke-warm, because then the disk would be even warmer. Moving air feels cooler than still air, so if the disk is, say, 12 - 14 degrees C. above room temperature (as my Seagates seem to tend to run; a couple of WDs that I checked ran a little warmer) the exhaust air (at a slightly lower temperature) should barely feel warm at all. it is either doing its job...or not, it may still be insufficient to keep the bearing and surface temperatures down. But a 1" fan in an enclosed space where there's no mechanical heatsinking, intuitively, isn't going to cut it. Our intuitions differ, then (or perhaps it's the disks we're used to using - mine tend to run only slightly warm to the touch). .... Well the purpose of my post was to find out if I'm not alone in my experiences. Citing the above example, that brand is just going to fail over and over - but only I guess for users who give it a duty cycle that's light enough to keep its temp down. Heavy seek loads are the worst. Video loads tend to use long accesses with relatively few seeks: while the disk head still has to follow the track, far less heat should be generated (I'd tend to suspect much closer to an idle level than to a heavy-seeking level). .... Why not just look around until you find a commercial unit that cools its disks properly? With external SATA units that should be trivial (no problem getting the S.M.A.R.T. information there). Any suggestions? How about this S.M.A.R.T. software, does it slow down access time? Any recommendations on whose to use? Modern disks include firmware that monitors their own operation and health, one of the outputs being their internal temperature. S.M.A.R.T. monitoring software just interrogates the disk to get that information out of it: there's no overhead at all save at the times you ask the disk a question (which shouldn't be that often unless you want to use the software to monitor temperatures for unusual changes rather than simply check them occasionally). I use a small free utility called Dtemp from http://private.peterlink.ru/tochinov/ and just start it up once in a while to see how things are doing (it reports a lot of other S.M.A.R.T. attributes too - Seagate drives are a little strange, since they come from the factory with non-zero values for some failing-health indicators, according to another S.M.A.R.T. utility from Adenix that I use less often). A quick look around turned up some other free utilities but none that could work through a USB connection (still hoping that someone here knows of one) - nor did the few paid-for utilities that I encountered claim to do so. - bill |
#8
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Failure of external HDD's - why doesn't any manufacturer wakeup to this?
In article ,
Thanks for that info Bill. OK since the Maxtor external drive I have on my home PC is out of warranty I just opened it up. Drive is suspended on neoprene(?) shock mounts. The only metal-to-case contact is via a copper earthing strip. Ventilation is a few square cm at the front and perhaps one sq cm at the back. Fan? Nil. This is going to cook - esp as it ages. opined thusly: richard wrote: In article vpadnVkUKdnZskvYnZ2dnUVZ_uejnZ2d@metrocastcablevi sion.com, opined thusly: Unless the internal air flow misses the drives, you can get a pretty good idea of how hot disks in external cases are getting by checking whether the exhaust-fan air feels warm (if not, the flow is probably adequate to keep the disks cool). Without voiding the warranty how can you know? If the air is cool it is either missing the drive or doing a good job. If the air is warm Actually, the air shouldn't be more than luke-warm, because then the disk would be even warmer. Moving air feels cooler than still air, so if the disk is, say, 12 - 14 degrees C. above room temperature (as my Seagates seem to tend to run; a couple of WDs that I checked ran a little warmer) the exhaust air (at a slightly lower temperature) should barely feel warm at all. it is either doing its job...or not, it may still be insufficient to keep the bearing and surface temperatures down. But a 1" fan in an enclosed space where there's no mechanical heatsinking, intuitively, isn't going to cut it. Our intuitions differ, then (or perhaps it's the disks we're used to using - mine tend to run only slightly warm to the touch). ... Well the purpose of my post was to find out if I'm not alone in my experiences. Citing the above example, that brand is just going to fail over and over - but only I guess for users who give it a duty cycle that's light enough to keep its temp down. Heavy seek loads are the worst. Video loads tend to use long accesses with relatively few seeks: while the disk head still has to follow the track, far less heat should be generated (I'd tend to suspect much closer to an idle level than to a heavy-seeking level). ... Why not just look around until you find a commercial unit that cools its disks properly? With external SATA units that should be trivial (no problem getting the S.M.A.R.T. information there). Any suggestions? How about this S.M.A.R.T. software, does it slow down access time? Any recommendations on whose to use? Modern disks include firmware that monitors their own operation and health, one of the outputs being their internal temperature. S.M.A.R.T. monitoring software just interrogates the disk to get that information out of it: there's no overhead at all save at the times you ask the disk a question (which shouldn't be that often unless you want to use the software to monitor temperatures for unusual changes rather than simply check them occasionally). I use a small free utility called Dtemp from http://private.peterlink.ru/tochinov/ and just start it up once in a while to see how things are doing (it reports a lot of other S.M.A.R.T. attributes too - Seagate drives are a little strange, since they come from the factory with non-zero values for some failing-health indicators, according to another S.M.A.R.T. utility from Adenix that I use less often). A quick look around turned up some other free utilities but none that could work through a USB connection (still hoping that someone here knows of one) - nor did the few paid-for utilities that I encountered claim to do so. - bill |
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