Monday 9 June 2014

Understanding and optimisng your SSD for maximum performance

 
Over the past few months I have optimised machines using newly purchased SSD and had to pass on this information to others. This is a consolidation of a few sources of information which hopefully you will find handy. It has been tried and tested but I do not accept any responsibility if you have luck or even bad luck with it. I ended up purchasing Samsung SSDs because of their capacity and the latest technology they were brining out, so you may need to interpret this for other SSD manufacturers, but most of the points below hold true no-matter the make of the SSD.
 
As with everything, please do the same as I did, research first test second, share third :)
 
   
Firstly it is worth while getting hold of the SAMSUNG magician software which tells you about a number of things you should be doing, if you don’t have the background already to configuring your SSD. It also has an additional advantage in that it can let you measure your disks performance without needing any other hardware
 
  
Starting from the PC architecture
 
  1. SSDs can capitalise on the latest AHCI mode over the older IDE storage communication mode http://www.diffen.com/difference/AHCI_vs_IDE. This will boost your read and write performance of your SSD from 10% to 20% (or higher for some machines).
    • CAUTION: If you have already installed Windows with a normal HDD, you need to edit your registry beforehand to ensure you machine will boot up if you change the AHCI setting in your BIOS - the instructions below are for Windows 8 and other operating systems will vary
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\storahci\
      • "Start" value should be set to "0" (Default is 3)
      • "ErrorControl" value should be set to "0" (default is 3)
      • "ImagePath" should contain "System32\drivers\storeahci.sys" and check that this file exists
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\storahci\StartOverride
      • "0" value should be set to data value of "3"
      • Sometimes this entry is listed as "1" not "0" but this should still be the value to change 
    • Please be aware that his is not a 100% guaranteed step, and you next alterative is to re-install Windows from scratch one you have AHCI turned on
  2. Update your drivers which should boost you disk significantly and stop any false readings (on some machines the IO is reported as running @ 10% due to out of date drivers) and especially the "Intel Rapid Storage Technology" if you can get hold of it for your machines (Released 14/10/2012)
    • Please ensure you go to your computer manufacturers support page and select the correct operating system before downloading the appropriate Serial ATA drivers.
  3. Ensure you are running on SATA 3 and not SATA 2 as for example Dell 9010 machine only have 2 SATA 3 ports one of which is connected to the DVD and the second to the shipped HDD. This can give you a spead increase of up to 100% performance
  4. Firmware updates are also important and for Samsung SSDs very easy to do.
    • CAUTION: If a firmware update signifies it needs you to take a backup, then please do so.
  5. Performance optimisation. A big misunderstanding exists behind disk defragmentation and SSDs. IN windows 8 the disk defragmenter is now called "Disk Optimiser". Both traditional HDDs and now SSDs need to be optimised which either moves files to eliminate fragmentation for HDDs and will clean up already used space on SSDs to ensure you can write to them faster. Please ensure you set a schedule in the Disk optimisers to optimise all your disks.
    • Please note that SSDs must also write on clean space which means that they will have to clean up the space before writing to it, which costs two cycles as opposed to one. Hence disk optimisation simple truncates and wipes the space before hand.
  6. Over Provisioning works in conjunction with disk optimisation but it also gives you one more advantage which you cannot gain by other means. It gives you
    • Faster overall write IOPS and
    • Better reliability with longer endurance of the SSD
      1. CAUTION: Do this early on in the use of the disk or it can fail to happen afterwards.
      2. All SSDs have a maximum number of writes per disk cell. So after that point the SSD cells will fail. To minimise this the SSD tries to spread all its writes evenly across the whole disk but as you can imagine this is a costly process, especially with small changes. Over provisioning allows you to keep some space free to both avoid the overhead of cleaning the disk before writing to it (and this also means less clean up operations) as well as it has a better way of provisioning new areas for use on the disk (minimising the amount of writes of files).
      3. Finally over-provisioning can be used to extend the life of the SDD as it can both better optimise the clean up operations and be used to replace SSD space which is near its end of life (the dead pool).
      4. Over provisioning 20% of the SDD has been measure to give a 250% improvement on write speeds of a full disk and overprovision of 40% has been measured up to 380% improvement.
      5. Also Intel official white papers indicate that the over provisioning by 20% increases the endurance of a 160GB SSD by 400% so the writeable capacity of the SSD changes from 15TB to 61TB. @ 40% overprovisioning you get an additional 130% endurance and this increase is despite the fact we reduce the actual capacity available to the end-user.
      6. But please note that the size of the write blocks is a big factor in determining the improvement and the measures above were based on 4k blocks.
  7. And after all this is done its time to make sure your Windows settings are correct
    • Turn off hibernation mode unless you really need it
    • Fix you virtual memory settings
    • Index Service and Searching is a debateable point and I usually turn this off when running VHDs on my SSDs
    • Deactivate Prefecth/Superfetch
    • Ensure Write cache buffer is enabled
    • Active Write-cache buffer flashing
    • Use maximum power setting for a system which runs VHDs
    • System Restore is a space hog, use it wisely
  8. New into the whole arena is RAPID Mode from Samsung. Available on 840 EVO and Pro disks it uses memory to significantly speed up read and write back with some amazing speed improvements of 100% on read and 50% on writes
    • It can only be configured for a single disk in your system by using 1GB of your RAM, but it does introduce a significant risk if you do not have an uninterrupted power supply unit (UPS) as you run the risk of a power down leaving your system in an unpredictable state.
    • I highly recommend leaving this setting turned off unless you can prove it has a benefit to your system as this feature only has specific measureable benefits but at the same time it can cause slow downs in other areas. See the "techereport" posted below were the Samsung 840 Evo disk actually drops in rating when Rapid Mode is turned on.
 
 
   
Sources of material
  
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