4 VelociRaptors vs 2 X25-M???

Discussion in 'Mac Pro' started by bbadalucco, Sep 29, 2009.

  1. bbadalucco macrumors 6502

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    #1
  2. Msbeezy macrumors member

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    #2
    I don't know about the Raptors but I have the latter (G1 tho) and they rock !
     
  3. frimple macrumors 6502

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    #3
    They're both going to be fast. I'm going Intel though. Random access (read/write) is really what makes a difference in the user noticeable speed of a system and there's no way rotational media can keep up with a SSD. Plus you don't have to listen to 4 VR's bang around in your case :D:p
     
  4. Tesselator macrumors 601

    Tesselator

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    #4
    I guess they should be the same speed roughly. The VRs will be faster at 64K benchmarks and much much faster at 1 MB ~ 100 MB tests. (all random) My 3-drive RAID0 composed of HD154UI Green drives, is faster than a single SSD. I would need 5 of them to beat the benchmarks I see produced by 2 Intel X25-M (Gen 2) in RAID0. But those are slow-ass green drives. :p Four VelociRaptors should beat my five green drives and should also be faster than the 2 Intels. Also the Intel SSDs are as slow or slower than regular drives when it comes to writing - both random and sequential.

    At sequential operations the VR's should blow away the Intels. And almost everything we do is sequentially weighted. The exceptions might be booting and massive database operations. The other exception would be multi-operational tasking. Like ripping a DVD, aggressively web browsing, and importing an 8 GB CF card full of images - all at the same time. Most people don't do that kind of multi-tasking but if you do then the SSDs might be a hair faster. The problem is that if you do do that kind of thing often then the SSDs end up being too small. :p
     
  5. frimple macrumors 6502

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  6. frimple macrumors 6502

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    #6
    I disagree with part of the first statement and all of the second. I think that sequential read (per drive) on the X-25's is almost twice that of a VR, so I would think that they would be about even (within 5-10%) on reads. On writes you're correct :p

    Just about everything that you do on your computer is going to cause random writes. This is why the crappy SSD's were so crappy and caused stuttering issues. If you think about the typical workload (writing a document, surfing the web, checking email and let's say zipping a file) you'll notice that it's a lot of small "random" writes going out to the file system and that's just writes! Let's say you also were playing some music, and now you've got a combination going. Now, if you're copying a large movie from you're media center over to your local disk then that's sequential. By and large the most prevalent type of operation to your disk is random. Not only do the VR's suffer from a somewhat lackluster speed on these, they also need seek time to get their physical head over to the next block.

    I'm a huge SSD proponent so I'm probably quite a bit biased, but for less money I'll take two X-25's over the VR's any day.
     
  7. nanofrog macrumors G4

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    #7
    This is what I'd expect as well. A pair of X-25M's should produce ~500MB/s seqential reads, but only ~140MB/s seqential writes.

    The VR's would produce ~480 - 500MB/s sequential reads, but the writes would be ~450MB/s, and definitely exceed a pair of Intel SSD's.

    But the price of it isn't cheap (WD3000GLFS can be had for $215USD), so 4x = $860. A better deal than the WD1500HLFS, as the best price I saw was $180USD. Despite this issue though, it's still cheaper in terms of cost/GB than the Intel SSD models, and that's off MSRP (thinking it's even worse due to the supply issues currently with Intel drives). If you figure in current street prices, it may not even be cheaper at all, even for the 80GB versions (no, I didn't check just before posting). :eek: ;)
     
  8. frimple macrumors 6502

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    #8
    I think you make THE point to consider against SSD's, Price/GB. Drive for drive I don't think there's a real world comparison that would show rotational drives to be superior to SSD's. The fact is that SSD's are a superior technology when it comes to performance today and in my opinion will be the standard in computers 5 to 10 years from now. However, because we're not in the future rotational drives are still a very viable media, mainly because of the cost/GB but also for their proven track record in reliability. Ever bone in my body says that SSD will someday surpass this, but the fact is right now for long term, large media storage rotational is king.

    yadda yadda yadda, SSD's still have the sting of early adopter pricing but do offer their own benefits!
     
  9. nanofrog macrumors G4

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    #9
    Mechanical drives do have better cost/GB, no doubt. Reliability may depend on one's definition. SSD's do have much better specs than they did of the not too distant past, but the published information is also based on manipulated statistics (best 90th percentile of cells, not all of them). So the read & write reliability are definitely not the same for SSD cells (NAND flash, either MLC or SLC variants).

    There are situations that mechanical do make better sense than just cash flow however, and that's in the write specs. They can't compete with fast SATA, let alone SAS (10 or 15k rpm units especially). So enterprise use will continue to use this technology until SSD can compete here performance wise, and definitely on cost.

    It all comes down to usage. SSD is fine for enthusiasts wanting faster random access (i.e. OS & apps), but has too many limitations for other areas ATM.
     
  10. pprior macrumors 65816

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    #10
    Don't forget to consider that 4 x mechanical disk in a RAID-0 = higher probability of array loss than 2 x SSD.

    If it's scratch or working space for video, then not critical, but if you're talking general drive useage, then it becomes one (Insert usual comments on need for backup, etc, that 90% of folks don't follow here).
     
  11. ungraphic macrumors 6502a

    ungraphic

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    #11
    Noise and heat produced by four Velociraptors would drive me insane. I'd just get two SSDs of slightly poorer performance but for a lot less money for RAID0, and get a 1TB HDD for files.
     
  12. nanofrog macrumors G4

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    #12
    VR's are enterprise drives, and aren't as dangerous as consumer models. Yes, the solution is backups, no matter the setup (HDD, SDD, single drive or arrays). If there's problems, and the backup doesn't exist, then the individual will have to learn the hard way. :eek: :p

    I only use a single 300GB VR, but I've not had issues with noise or heat.
     
  13. Tesselator macrumors 601

    Tesselator

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    #13
    That's right. And this proves my point expressly. My 3-drive Green RAID0 gets 500 ~ 600 MB/s writes and 300 ~ 350 MB/s reads. And those are slow-ass green drives.

    I stand pretty much by what I said.
     
  14. gugucom macrumors 68020

    gugucom

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    #14
    I would still take the SSDs over the Raptors considering the noise, energy and mechanical failure issues of those. Just to get rid of the heat of the raptors is an issue in confined spaces.
     
  15. ungraphic macrumors 6502a

    ungraphic

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    #15
    I have a question also;

    I have two 250gb Western Digital Hard Drives, exact makes are:
    WD2500AAKS
    WD2500KS

    I've got these two paired up in software RAID0, thus making it a 500gb total boot disk. It runs quite well, at least, better than a single 250gb drive.

    I've been itching to get an SSD drive, replacing the two drives; less noise, less heat and of course, better speeds. However, 80gb is the bare minimum i'm willing to deal with, right now i'm using 61gb of my 500gb disk (some photos and stuff are loaded onto it as well, which will be burned to dual layer DVDs, so really, i only use around 50gb of space). Thing is, I know sometimes the main drive can get packed with files that get transfered over to my storage drive (as well as my backup drive).

    My questions are;

    1)is it worth it upgrading to a single SSD drive for me? I have the money, its not really an issue, its a matter of logic. Any SSD drive that holds more than 80gb costs quite a bit. However, at the same time, I could buy two 60 or 64gb SSD drives and RAID0 them to make quite a fast drive.

    2) I've asked about this before, but would garbage collection/TRIM have any real advantages over an SSD without it? Is it worth the wait (and money saved from the wait).

    3) Does OS X's automated defragmentation really hinder an SSD drives over all life expectancy? I keep reading stuff about '100K write cycles per cell' is this even something to worry about?

    4) MLC vs. SLC? Whats the REAL difference?

    I can get a 120gb MLC drive for $369, 220mbs/200mbs read/write speeds: http://www.newegg.ca/Product/Product.aspx?Item=N82E16820139030

    Or 64gb MLC drives for $199 each, 220mbs/140mbs read/write speeds:
    http://www.newegg.ca/Product/Product.aspx?Item=N82E16820139030

    Going with the pair would be a little more expensive, but would provide (theoretically) double the performance in read speeds, and about 40% boost in write speeds (280mb/s vs. 200mb/s)

    I've been holding off on installing Snow Leopard on my machine mainly because i've been wanting to get a new drive for it, but i've been putting both off for a while and its been kind of bugging me.
     
  16. nanofrog macrumors G4

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    #16
    I happen to agree. SSD's cost/capacity is absolutely lousy, and it performance reign is only for random access use (when compared to an array of mechanical drives). It's equal at best on sequential reads, and totally lacking in seqential writes.

    So they're great for an enthusiast that wants a single, fast drive, and uses it for primarily reads (OS & loading apps), and data to a mechanical unit for the capacity.

    It's not yet ready for use in heavy write situations, such as banking, scientific research, video/graphics work,....
    I've not found them to be noisy or hot, but the issue of confined space can be an issue, and needs to be taken into consideration.

    But if the engineers did their jobs correctly, the drive area should have adequate airflow for proper cooling (acceptable standard is 45C, with 55C being the max limit). I've not seen VR's get that hot. Mine tends to hover in the 29 - 33C range (idle - avg. load respectively), which is rather cool for any mechanical drive. :)

    Single drive = NO, given the cost. The usage matters, and if you're extremely constricted for locations (i.e. a single drive space is available), then it may be a solution. But you've not indicated this is an issue.

    Yes, TRIM is worth having. Waiting also will do something else that isn't mentioned much. OS's will be equiped to deal with SSD's (currently they're designed around mechanical drives). This will change, but OS developers need time to work it out, and make it reliable (won't wear out the NAND cells).

    Yes. It's not needed for SSD's, and it causes unnecessary wear on the cells. This is part of the changes needed in OS's.

    MLC = 10k writes
    SLC = 100k writes (worst case data from the NAND flash manufacturer)

    SLC is also faster, but more expensive. So the less expensive drives will be MLC. Always a compromise.

    Please note that the reliablility data published by SSD makers is based off a 90th percentile model, and also includes the affects of wear leveling. The flash makers use a 100% model, and no wear leveling (that's a function in the drive's firmware, not built into the flash itself).

    Your presumptions about RAIDing 2x of the 64GB models would be correct. It would effectively double the performance, so ~440MB/s for sequential reads and ~280MB/s sequential writes.

    Owners of the '09's would be limited to a max of 660MB/s though, as the ICH10R in those systems are throttled to that rate, no matter what they should be capable of (i.e. 6x Intel SSD's would be capable of ~1.5TB/s max in a stripe set for reads).
     
  17. ungraphic macrumors 6502a

    ungraphic

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    #17
    ^Thank you!

    Do you think OS X 10.6 will get SOME kind of update for proper SSD drive support? It's quite stupid that the Macbook Air got released with an SSD drive, but OS X 10.5, and even 10.6 didn't get proper support for such a drive.

    Also, as for 'MLC = 10k writes' is this a real concern? How do these cells work? I move around files frequently, especially with photographs. Could it mean something like 10,000 writes as in, writing 60gb of data to a 60gb drive, 10,000 times before its a DEAD drive?
     
  18. nanofrog macrumors G4

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    #18
    I'd hope so, but there's no way to be sure.

    To me it is. But what you'd get with a drive, is still better, even in a worst case scenario, due to the wear leveling feature. Also, the more unused capacity on the drive, the longer it can last, as there's more cells for the wear leveling feature to use, when cells go bad.

    What that number actually means, is the cell itself. You can check wiki out if you need or are interested in more details. ;)
     

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