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The SSD myth unraveled

Sep 15, 2011 8:48 AM


Written September 2011.

 

Introduction


SSD's are hot. Everybody talks about them and they are rumored to be the non-plus-ultra for performance gains. I write this to create a more realistic view on where we are now with SSD's.


SSD's have the reputation of being very fast, much faster than conventional hard disks. There are many reports on the internet that investing in SSD's will give you huge performance benefits and that is the explanation why so many people consider SSD's a must have for the ultimate performance experience. Unfortunately - and this is especially true for video editors - this is mostly a hype and not a wise decision.


Let's start with the basics.


They are physically small, have no moving parts, are quiet, cool and expensive per GB. The small physical dimensions mean that you can easily fit 4 SSD's in a single 5.25" bay. Because there are no moving parts they are quieter than conventional disks. They also operate at lower temperatures than conventional disks, which is a distinct advantage in a crowded system. Average access time is negligent in comparison to conventional disks. SSD's are not as susceptible to fill-rate degradation as conventional disks. (Conventional disks tend to show performance degradation when filled for more than 60%. Not so for SSD's). But there is the cost aspect and the reliability question.


But the most important question is performance. Does it justify the extra cost for the increase in performance?


Currently, the price per GB for a SSD of the latest generation is generally around $ 1.40 - $ 2.00, depending on the model, capacity and brand. A conventional disk is around $ 0.05 - $ 0.06 per GB and that means a SSD is around 30 times more expensive per GB. Is it worth the difference?
According to many, the answer is yes, it is worth it, but I beg to differ. Proponents of SSD's claim that the transfer rates of SSD's with figures of 500 MB/s are way faster than the 120+ MB/s of modern conventional hard disks and that justifies the extra cost. If this were true, why don't we see those performance gains in our benchmark? What is wrong with these claims of unprecedented speeds?


The background


Manufacturer's claims of IOPS - which are irrelevant for video editing - and sequential transfer rates are based on highly compressible data in 4K blocks, something that video data are not, because they have already been heavily compressed. It boils down to writing only 0's and compressing those 0's to achieve the claimed transfer rates of 500 MB/s, but effectively only around 30 MB/s are transferred. If you were to test effective transfer rates using CrystalDiskMark, which uses random data to benchmark, the compression is far less, because it is random, and then the effective transfer rate of SSD's is reduced to something in the order of 200 MB/s. With video data, the effective transfer rate could well be even much less because of the heavy compression that has already taken place during the shoot.


Interesting to see, and I do not know the answer, whether a heavily compressed codec like AVCHD would show lower transfer rates than less compressed codecs like P2-Intra or 50 Mbps MPEG2.


Write degradation


This is one of the most discussed issues with SSD's. On new SSD's the write speed is almost as good as the read speed, but when using that SSD for a longer time there are serious performance issues while writing data to a SSD. Even with the latest generation SATA3 / Sandhurst SF-2281 SSD's, write performance can easily drop by more than 60% despite the TRIM function. This effectively means in the best case scenario, that a SSD with a claimed transfer rate of 500 MB/s, which delivers less than 200 MB/s read speed with video data, can only deliver 80 MB/s or less write speed when used for some time. That is not too impressive in comparison to conventional disks at a fraction of the cost and less than a simple raid0 with two conventional disks on a ICHR10 on-board controller attains.


If TRIM is not working, the write degradation is even worse and you may count yourself lucky to attain write speeds of 50 MB/s or less. Unfortunately, most SSD's firmware in combination with raid controllers currently have the nasty side effect of disabling the TRIM function, so raiding SSD's is not a serious choice for raid configurations.


The only way to correct this write degradation is by performing a secure erase, which means losing all the data on the SSD, not a nice perspective for anybody, but most of all for notebook users. Are your backups current?


Reliability


NAND memory is susceptible to ageing and most SSD's calculate their lifespan in data transfer values. In a worst case scenario this usually means you can rewrite the complete contents of a SSD around 125 times, before the NAND memory is no longer reliable/useable. Not many people would try that and for a boot disk this means a very, very long time before the useful life of a SSD is at an end, but for video editors it is a different story.


The bottom line on SSD's at this moment of writing

 

  1. They are the way to go in the future, but not yet.
  2. For OS & program disks they are great, provided you set up Windows to not use the SSD for temp storage. They can easily shave off 3 or 4 seconds from your usual boot time of 60+ seconds, depending on your configuration. (Did you notice any sarcasm in this statement? You should.)
  3. They are a waste of money for video storage and do not deliver any performance gain, because of the compression that has already taken place with the video material and that lowers the transfer rates significantly.
  4. The faster loading of programs, which is often used as an argument for SSD's, is usually limited to 1 second per program or not even be noticeable.


Question


What would you rather have at this moment:


a. 8 TB of net storage with conventional disks for around $ 400 with a sustained transfer rate of 1000 MB/s, or
b. 2 TB of net storage with SSD's for around $ 3000 with the same transfer rate?

 

Just my $ 0.02

 
Replies
  • Currently Being Moderated
    Sep 15, 2011 2:28 PM   in reply to Harm Millaard

    Interesting to see, and I do not know the answer, whether a heavily compressed codec like AVCHD would show lower transfer rates than less compressed codecs like P2-Intra or 50 Mbps MPEG2.

     

    I'd expect them to be the same myself, since there is no further compression going on with a read during editing or even during a file copy.  The 1's and 0's are simply read as they are.  (And written as they are, if copying.)  What those 1's and 0's represent should make no difference whatsoever to the reading or writing process.

     
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  • Currently Being Moderated
    Sep 16, 2011 6:58 AM   in reply to Harm Millaard

    Nicely summed up. That pretty much consolidated all the info from the other treads.

     
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  • Currently Being Moderated
    Sep 20, 2011 8:11 PM   in reply to Harm Millaard

    With all due respect, SSD's are not meant to be used as mass storage or scratch disks at this point in time. They are marketed specifically to be used as boot drives. In that respect they perform VERY well... IF... they are setup correctly.

     

    First, they MUST have proper partition alignment. I believe Vista will perform the alignment properly on a new SSD (apparently by shear luck), and Windows 7 supports SSD's by default. Windows XP does not perform a proper alignment so it's up to the user to do it before anything is written to the SSD. If not properly aligned, you just slowed down your brand new SSD by 50%. Sorry, I don't know anything about the Mac OS capabilities.

     

    Also, cloning software MAY overwrite your perfectly aligned SSD and it ends up misaligned. If you're not sure if this will happen with your backup software, align and partition the SSD correctly and then copy "partition to partition" making sure not to resize or move the partition. This is especially important when moving from HDD to SSD. If you clone a HDD, you could be asking the software to rewrite the partition alignment without knowing it.

     

    Next, if TRIM isn't working, it's all downhill. If an SSD is forced to erase before it writes, you just lost any real gains. Some older SSD's need new firmware to handle TRIM. More than likely, a firmware update is available to solve or enhance other features too. Always check for a firmware update before you even begin because some updates might destroy any data on the SSD while others are less destructive.

     

    I've been using an SSD as my boot drive on XP 32bit for well over a year. It's much faster than even the fastest HDD's, uses a fraction of the power and 100% silent. It hasn't slowed down at all in that time but I also did a LOT of research before ever installing it. There are tons of system tweaks to take full advantage of , especially on XP. In looking for those tweaks I discovered the added benefit of using RAM above the 4GB that XP can see for scratch disks and virtual memory etc.

     

    Another important thing to know about SSD's is to refrain from constantly benchmarking them! As stated, each cell can only be written to a limited number of times, so constantly benchmarking one can kill it before its time. However, the useful life hinted to in the OP is far below what today's drives can produce. On an average system, most new SSD's should last at least 5 years and that's longer than a lot of people keep a computer these days. Again, keep in mind, the average boot drive does a lot more reading than actual writing as long as you keep page/swap files, scratch disks, temp folders, cache files and anything else that is constantly updated on your fastest HDD and off your precious SSD.

     

    I've had such great success with my XP SSD, I added another one to boot into Win7 64bit and it was a breeze to install by comparison. Again, the OP's experience varies greatly from my own because I reduced my boot times by almost 1 minute with XP. Granted, my system may be configured far differently than his. If you only have a few programs loaded on a business system, you may not see as much reduction in boot times. But my system is like many other home/office systems with programs accumulated over the years and a registry as long and crooked as the Mississippi. I don't look forward to reinstalls so I prevent them with a passion. The trade off is, the longer a Windows system stays up and running, the messier and slower it gets. But I offset that with regular maintenance, backups, and overclocking. I guess being an ex-computer tech has its benefits and hindrances.

     

    As far as SSD's go, I can appreciate a forum such as this steering people away from them but you have to understand why. They aren't meant to be upgrades for the inexperienced users (yet). You have to know what you're doing and what to expect. SSD's are improving by the day and still aren't meant to be mass storage devices or used as project disks etc. But as boot drives, you cannot beat them. As for laptops, you should seriously look into an SSD when it comes time to upgrade the HDD. Less power consumption and they can cut your boot time in half. I opted to upgrade my laptop with a hybrid drive which uses a SSD cache for storing popular system files on a HDD with loads of storage. That also cut my boot and load times almost in half after the 2nd boot. Far cheaper than true SSD and lots more storage.

     

    PS. I'd like to thank the OP for his help in another thread which prompted me to move to 64bit for CS5.5 and help choosing a new graphics card. I can tell you the Zotac GTX580 AMP is fantastic and works great with CS5.5. I can overclock it to almost 1Ghz on water cooling but that's more for fun than actual rendering speed. Thanks again!

     
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  • Currently Being Moderated
    Sep 23, 2011 5:14 PM   in reply to AdobeHasIssues

    So, are there cloning software that are SSD aware?

     
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    Oct 5, 2011 12:06 PM   in reply to Harm Millaard

    Great post!

     

    Thanks

    Phil

     
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  • Currently Being Moderated
    Oct 11, 2011 11:43 PM   in reply to Harm Millaard

    Currently researching the best machine for Photoshop use, and was considering SSDs. Did a small amount of research this evening and ran across this thread.

     

    What really scares me is the reliability issues with SSDs. Go to Newegg and look at the customer feedback. Almost no SSD is rated over 4 stars, and most are 2 stars. The feedback is invariably the same: "drive died in six months"...or less.

     

    Apparently the only SSD drives with decent reviews are Intel SSDs in the 80GB size. These are the drives that enterprises use, apparently.

     

    I've decided to forget about SSDs. Who cares if Windows boots faster? My clients turn on the box and leave it on! Only when they leave for the weekend is it turned off (or on hot summer days, they may turn it off on weeknights to cool down the production room (San Francisco, no air conditioning except for a mobile unit.)  Same with Premiere or Photoshop. Usually it's started and left on, just switching projects. So who cares about saving a few seconds on program load?

     

    If you can't use an SSD for data swapping, cache or whatever, it's essentially worthless considering the price.

     

    Now Intel does have a new trick coming out where a 20GB (or larger, but they make a 20GB expressly for this purpose) is set up as a CACHE for an existing hard drive (or RAID). The result is a hard drive/SSD combo that approaches the speed of a much larger SSD. There are some limitations and some questions as to whether it's really worth it, but apparently you can take a WD Velociraptor 10K drive, front it with an SSD and turn it into something reasonably close to the same speed as an equivalent capacity SSD. Might be worth looking into. Just a thought. Only works with the Intel Z68 Chipset and Intel software, however. See here: Intel Z68 Chipset & Smart Response Technology (SSD Caching) Review

    http://www.anandtech.com/show/4329/intel-z68-chipset-smart-response-te chnology-ssd-caching-review/2

     
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  • Currently Being Moderated
    Oct 19, 2011 9:57 AM   in reply to Harm Millaard

    Harm

    Having used two SSDs for the past eleven months I tend to agree with all of your observations.

    The first SSD acquired was a Kingston 128Gb in spite of my research indicating questionable reliability. It was, as the proverbial phrase goes "walking the bleeding edge of technology", I could not help myslelf but to try one out.  Since my comfort level was low I used it only for cashing.

    Since it appeared to funtion without issues and after increasing my RAID setup, it seemed a safe step to move up and get a 6Gb/s SSD and Intel's 510 series was the choice. 

    Yes, it makes moving around the operting sysetm a delight, but at a cost, and not just money!

    To get 6Gb/s performance (actually it is 5Gb/s at best) requires additional software, in my case Marvell 91xx.  Unfortunatly this makes the setup with one SSD appear as a RAID configured drive.  As such the TRIM function is disabled.  At least that is what Intel's SSD Toolbox indicates.  Since I'm inclined to be meticulous about my drives to ensure integrity, on a monthly basis I moved said drive from the 6GGb/s port ot a 3Gb/s to run the TRIM optimizer and subsequently moved it back to the 6Gb/s port.  This worked for the previous two times, but not this past weekend.  When, after running the TRIM optimizer and moving the drive back to the 6Gb/s port it was no longer recognized.  Without going into details, the end result was a system drive no longer being recongized as such, requiring a completed drive restore from the backup files, which thankfully was done the day before.  Five hours later all appears well with a 6Gb/s SSD in a 3Gb/s port and still as a system drive. 

    As stated by several here SSDs are not ready for the inexperienced user like me.  Although, I'm not replacing it and my next laptop will have one...

    Cheers,

    Michael

     

    Footnote - Performing the TRIM actually started to slow down the read speed on both the 3 and 6Gb/s busses by 12%.  The subsequent re-install of the system brought it back to its orignal read speed.  Hence, I won't be using Intel's TRIM utility until more information on this is made available. 

     
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