SCSI hard drive help

Discussion in 'OT Technology' started by rudy6482, Apr 16, 2009.

  1. rudy6482

    rudy6482 New Member

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    Im building a pc & im considering installing SCSI hards drives, mainly for dependability. Is it worth the extra cost? Can I use any SCSI card with the same connection? And whats the advantage with solid state drives?
     
  2. Hate Crime

    Hate Crime Don't Hate OT Supporter

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    dont waste your money
     
  3. lowfat

    lowfat 24/Mac/SciFi/PC Crew OT Supporter

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    SCSI is old as fuck.
     
  4. rsxm5

    rsxm5 OT Supporter

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    So what? You make it sound like it's no longer a worthwhile technology...
     
  5. StevesVR4

    StevesVR4 Get Arrested

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    SCSI? Now? SCSI drives are quickly being discontinued. Does anyone even make SCSI controllers anymore? If you insist on spending extra, buy SAS drives. But if you main purpose is to buy drives for dependability, purchase the enterprise level SATA drives. Seagate calls them ES and ES.2. Western Digital calls them RE3. They are designed for 24/7 operation but are available at much lower price points compared to SAS drives.
    As for solid state drives, their big advantage is read access (provided you avoid one of the many drives based on the JMicron controller). The problem with solid state drives is they are even more expensive per GB than the SAS drives.
     
  6. dissonance

    dissonance reset OT Supporter

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    Aside from just getting enterprise class drives, SAS has an extra advantage over SATA in that it "should" be a more reliable and better performing interface. You can get some cheap SAS drives on newegg...

    But if all you need is "dependability", just get a SATA/SAS RAID-6 card. RAID will always be more dependable than any single drives.
     
  7. StevesVR4

    StevesVR4 Get Arrested

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    Cheap SAS drives on Newegg? I just did a search and the cheapest SAS drive they offer is $139.99 for a 73.5GB Fujitsu drive. At ~$2 per GB, it is not exactly cheap. You will see a performance improvement since the drive does spin at 15K RPM compared to the 7200 RPM of most SATA drives plus the SAS protocol should be more efficient that the SATA protocol. But for a home user, the price premium for SAS is usually not worth it. For "dependability" you could purchase two Seagate ES.2 250 GB drives for a total of $149.98 and RAID-1 them. You get over 3 times the space for only $10 more plus the data is mirrored over two drives in case of failure. Also, there is no need to buy a separate SAS controller so you can save that money too.
     
  8. dissonance

    dissonance reset OT Supporter

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    I only called newegg "cheap" in comparison to most places. SAS drives are expensive in comparison to SATA but newegg actually has good prices on new ones... I was just giving him a store recommendation for "cheap" SAS drives (provantage.com has a better selection and decent prices, their shipping is generally more than newegg though).

    As for SAS vs SATA. I agree that unless performance is a major priority that a SATA RAID would be the way to go. I only mentioned SAS since it seemed by the original post that the OP was interested in higher end by mentioning SCSI and SSD. As for SSD, they are great performers but high priced for "decent" ones. Their dependability isn't really tested for storage so much since they haven't been around too long (what I mean by this is how well different drives do with moving data around within the flash modules to keep from only reusing the same modules over and over and have some that have been written to once and never wrote over).

    As for the RAID part, if end up doing RAID-1, the mobo based controller is fine. If you do any other RAID level you'll want to get an actual RAID controller. Promise, LSI, 3ware, Areca are all good brands (though 3ware was just bought by LSI).


    BTW OP, what is the going to be the use of this machine? How much storage is needed? What kind of budget do you have for the storage aspect of the build? How expandable does it need to be and is it more of an archive or actively written to?
     
  9. deusexaethera

    deusexaethera OT Supporter

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    SATA is built to the same durability specs as SCSI. In fact, the only difference between SATA and SAS (the new version of SCSI) is the circuit board; the mechanical parts are all the same.
     
  10. dissonance

    dissonance reset OT Supporter

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    I wasn't and I don't think StevesVR4 was referring to platter/head/magnet makeup of the drives.

    If we want to go deeper into it, we could suggest a Nearline SAS drive to the OP.....
     
  11. rsxm5

    rsxm5 OT Supporter

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    You are kidding right?
     
  12. Chris

    Chris New Member

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    Just buy enterprise class SATA drives
     
  13. rudy6482

    rudy6482 New Member

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    This machine is goin to be a home pc, but I will be using precision ag software thats expensive. Thats my main reason for wanting dependability. I'll spend the extra money if its worth it. The computer I have now has a scsi hard drive and its ten years old.
     
  14. dissonance

    dissonance reset OT Supporter

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    Go with a decent RAID controller and a RAID-5 with enterprise SATA drives. As for the drives, if you get 1TB ones, get the Hitachi enterprise one, otherwise Seagate ES.2.
     
  15. deusexaethera

    deusexaethera OT Supporter

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    No, I'm not. Common knowledge might be failing me in this case, but nonetheless it's common knowledge that the mechanical parts are all the same nowadays, and the only differences are in whether the firmware employs conplex (and expensive) algorithms to optimize data throughput or not.

    In any event, I've disassembled plenty of IDE, SATA, and SCSI hard drives, and they all look the same inside. Notably, though, the IDE and SATA drives usually have a couple of blank spots on the circuit board where extra ICs could go, and the SCSI ones don't have blank spots.
     
  16. rsxm5

    rsxm5 OT Supporter

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    Not even close...

    Here is the inside of a 15K rpm SCSI or SAS drive
    [​IMG]

    Here is the inside of a SATA drive
    [​IMG]

    Notice the difference in the size of the platters. The SCSI/SAS drive has much smaller platters. Also, the circuit boards and electronics are VERY different... By your logic, I could take the 15,000 rpm motor from a SAS drive and put it in a SATA drive and have it work properly. I hope you know better than to think that is possible.
     
  17. deusexaethera

    deusexaethera OT Supporter

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    Of course it's possible to swap the motors. Have you ever looked at those motors, or played with them outside of a hard drive? They are 3- or 4-mode brushless DC motors, and the speed they run at is controlled by how fast the control circuit fires each armature coil in order; if you just apply current to one pair of the motor's contacts, it will swivel to a specific position and stay there, unlike a "normal" motor that will continue spinning. Obviously the wattage supplied to the motor also has to be increased to provide the energy to spin it faster, but that is controlled by the circuit board, not by the motor or its wiring.

    Like I said, I've taken apart dozens of hard drives at this point, and I've seen a wide variety of configurations, but nothing that makes SCSI and IDE fundamentally different. For one, that SATA drive you linked to had the top magnet removed from the arm actuator, presumably to show off the sexy copper coil underneath, so that doesn't count as a difference. Also, a lot of SCSI hard drives do have smaller platters, but a lot of them have the same size platters as slower drives as well. I have two good examples of that sitting on my desk right now, and three more plugged into my computer. The faster drives sometimes have smaller platters to improve seek time and to reduce centrifugal force on the outer edges, but it's hardly a necessity for them to be that way.

    The simple fact is that it's cheaper to mass-produce parts that meet the most demanding standards and then "dumb them down" by installing cheap control circuitry, than it is to make totally different non-interchangeable parts for each type of hard drive. As for why anyone would pay for the better drives if that were the case, that is equally simple: it doesn't matter why it runs faster, just that it runs faster. It's not like people who buy hard drives are going to open them up and then bitch about how the motor should be able to run a couple thousand RPM faster -- that is totally beyond their need-to-know.
     
  18. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I don't know about the physical differences today, but as recently as a few years ago there were some mechanical differences.
    Different controllers, connectors and also different bearings. And they were rated for 24/7 use, as opposed to 8 hour per day ratings of ide drives.

    Today, who knows. I haven't read about it in ages.
    But I have to admit feeling somewhat sad that SSD drives are going to forever eliminate the advantage of scsi. It's just a matter of time, now.
     
  19. deusexaethera

    deusexaethera OT Supporter

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    I know what you're talking about, but if you look at the MTBF ratings on drives over the past few years, the number jumps way up when the switch from IDE to SATA happens. Modern drives are all the same on the inside.

    I dunno if SSDs will ever be able to top the sustained write speed of SAS drives, just because in an SSD every disk access is effectively a random access. Probably spinning platters will eventually become the backup medium of choice, since they are so much better at streaming data.
     
  20. XR250rdr

    XR250rdr OT Supporter

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    doosh if you had any idea what it took to profitably manufacture millions of drives per year you would quickly realize how full of shit you are. Just because two parts look similar on the surface in no way makes them the same. Hard drives all use the same method of head actuation, but that doesnt mean the heads are the same.

    They can achieve the economies of scale necessary to make money on drives by having each drive family share parts, not their entire drive business. It makes no sense to make a million parts to a higher than necessary specification.

    MTBF ratings in the desktop sector have been increasing steadily since hard drives were introduced. There was no giant leap when SATA came out at all. Go compare the first SATA drives vs their ATA counterparts. The reliability is all the same.
     
  21. deusexaethera

    deusexaethera OT Supporter

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    Last I checked, the SATA drives I looked at were rated at 1.2Mhrs MTBF, just like SCSI/SAS drives, while IDE never really got above 100khrs MTBF. But they do say 98% of statistics are made up, and quoting statistics makes your argument 63.7% more believable, so...:dunno:

    Do you work for a hard drive manufacturer, by any chance? Is your font of firsthand knowledge that much bigger than mine?
     
  22. XR250rdr

    XR250rdr OT Supporter

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    Only ES.x and RE.x series are. Those aren't desktop hard drives. They are enterprise level SATA drives.

    7200.11 series drives are rated at 750k hours.

    Seagate ATA V drives (1st series they had IDE and SATA) were rated at 600k hours. ATA IV series was also rated at 600k hours. Those are seven year old drives. Go back to 1996 and the Medalist drives were rated at 300k hours.

    No, not a drive manufacturer. I work for a contract development and manufacturing firm. In a nutshell we design and manufacture products for other companies to their specifications. If we were building two similar products that could share certain parts, but one device needed tighter tolerances I would be laughed out of the building if I suggested we use the same parts for both units. The only real exception I can think of is very small quantities using processes that have very high tooling costs, like injection molding (molds usually run $50k+). However engineers will usually specify processes designed for low quantities to get around that.

    One thing I have learned is that just because two parts come from the same source (talking component parts like motors) doesn't mean they're even remotely similar. The only way to be sure two parts are the same is if they have the same part number.

    If you want my $0.02 towards the original topic, unless the user needs the high throughput of 15k SAS drives, enterprise level SATA drives will be just as reliable and a whole lot cheaper. Remember also it never hurts to not skimp on a good RAID controller either. Although for RAID1, ICHxR based onboard controllers are probably fine.
     
  23. deusexaethera

    deusexaethera OT Supporter

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    Fair enough.
     
  24. Doc Brown

    Doc Brown Don't make me make you my hobby

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    You seem to have a bit of insight onto the onboard RAID controllers... I've been wanting to do a simple 2 drive RAID 1 array. And I don't mind spending the money for a quality hardware based controller. I would hate though, to spend the money if the onboard ICHxR controller would do good enough.
    However, there's nothing I would hate worse than running into some weird shortcoming as soon as a drive failed on me and I had to replace it.
    So to get to the point, just how reliable is an onboard solution when compared to a hardware controller?

    I'm considering in the 3000 series HighPoint cards. From what I understand, all the 2000 series ones are software solutions.
     
  25. XR250rdr

    XR250rdr OT Supporter

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    With RAID1 if the controller dies you can still access your data just fine. If you want to go with a higher level, by all means get a good hardware based controller. Intel makes good chipsets, I see no reason to worry about the on-chipset RAID controller dying until the whole motherboard does.

    I don't have any experience with those HighPoint cards though so I can't say anything about them.
     

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