5640 Views 8 Replies Latest reply: Jun 27, 2010 8:47 AM by MacRS4
How long have you had the drive?
How hard do you use it?
How do you know its slower – through everyday usage or through benchmark tests?
This is the issue with SSDs - they slow down over time. Its the way they store and then remove data. Basically, when you delete something, its marked as deleted but not actually removed from the disk. Hence, next time you write data to them particular memory blocks, it needs to wipe the old data and replace it with the new, which takes a little more time.
There is a feature called TRIM, which basically runs when the drive is idle, and sets about 'cleaning up' the disk so that its ready to be written on, and hence faster.
However, firstly your SSD must support TRIM, and your OS must also support TRIM. Currently the only OS that supports TRIM is Windows 7, unfortunately. It seems that with the recent 10.4.6 update, TRIM support is being added to Snow Leopard as it is listed in the system properties, but its not actually 'switched on' yet. Maybe Apple haven’t quite got the full functionality going yet......
SSDs come with an ‘Indilinx’ controller built into them. This is a slightly older controller, which needs TRIM since, as you’ve noticed, the drive tends to slow down over time.
However, newer, and more expensive SSDs, are being released with a new ‘SandForce’ controller. There is secrecy around how this controller works, but its reported to do the TRIM feature on-the-fly – so it doesn’t suffer from slow down issues. I have a Vertex 2 SSD, which has the SandForce controller, and although I haven’t had it very long, its as fast as when I first installed it, and it should stay very close to this speed, as other people who have SandForce drives have noticed with their benchmarks.
The only way to speed up you drive to how it was when new, at the moment, is to use a tool to perform a clean reformat (a normal format wont do). You’ll need to search Google for a tool that does this with SSDs as I haven’t looked into any. The downside is that you obviously need to reinstall everything from scratch afterwards – hence it comes down to whether you can be bother to go through the procedure. Your SSD should still be much faster then a HDD even in its ‘slow state’.
yes, I experience the same with my OCZ vertex. Although it has TRIM and was working fine on my win7 laptop, I put it on a mac book and performance degraded slowly but surely.
to follow up on the previous post, here the solution:
1st: backup your disk (time machine) or clone it
then you have 2 options:
if you have a second computer, take the SSD out of the MB and plug it to your 2nd computer (via SB/FW enclosure, internal) and do a zero-fill (google that term for software, there are a few freeware around) then reinstall MAC OS using your time machine or clone.
option 2, which I recommend, clone it using superduper (it's money well spent) to a external disk.
then you boot from that external disk and your format your internal SSD with a zero fill option.
then you clone back your mac os system to the SSD.
you will get your performance back.
I like superduper because it gives another install of MAC OS which I use for testing software.
I've done it once and plan to do it every 3 months.
option 2 is easier as you don't have to remove the SSD. if possible do consider using a FW800 external enclosure for cloning the SDD. it's a lot faster.
A zero-fill will simply not write-erase your drive to return it to performance. OSX doesn't support TRIM - it does report it though in system profiler - it does on 10.6.3 too, I'm not convinced there's additional SSD features in 10.6.4:
To my knowledge there are no current reliable ways to to a firmware level secure-erase on Macs unfortunately. I've seen a couple of potential solutions floating about but never had much luck with them.
To be clear, to return the drive to 'factory performance' you must write-erase it using the firmware utility built into the drive.
Have a look at my article here: http://www.markc.me.uk/MarkC/Blog/Entries/2009/8/13Erasing_anSSD.html
It explains how to write-erase, and even includes a boot disk to do it - you'll need a 'normal' PC to do it on though.
Message was edited by: MacRS4
a zero does work but you made me doubt.
I did a zero fill on partner's windows laptop (also a 120gb vertex) 3 days ago and I definitely see a significant difference in the boot time. I reboot the machine 5 times and let her use it for a couple of days before measuring the boot time. it's 20% faster.
The zero fill was done by connecting the SSD to my imac via usb and did a zero-fill via the disk utility (1 pass)
thanks for your links, though.
I'm not going to argue with you about it - if it works for you, then great I guess.
I will repeat again though, for anyone else that may want to follow your advice, that a zero fill will not return an SSD to its factory performance. Only a write-erase process will.
Think about what you're doing - you're writing out the value zero to every block on the drive. Why not write out 1? Or 37? The point being as far as the SSD controller is concerned each block has been written - that's your issue. The controller hasn't a clue that by writing out a zero what you're actually saying is 'I don't care now what's in these blocks'.
The write-erase process will mark each block as un-written. This means that any existing data in a page block is ignored during a write process, it is not read out, the block erased, and then the entire block re-written.
With a 0 write any write to a block is actually going to read back the written blocks and then write out the whole page. Have a read of this article it explains how most SSDs work: http://www.anandtech.com/show/2738/8
There are newer controllers out there that that do write wear levelling better than older controllers it's true, but they still suffer write degradation eventually.
My guess is you're seeing other benefits from a zero fill - maybe reduction in defragmentation or the like - not that that in itself should matter much on an SSD.
I've yet to find an SSD that, when full and written to, doesn't degrade compared to a fresh write-erase scenario.
How long is it taking for you guys to experience degraded performance? Can you give me a rough estimate in hours used?
I have an ssd and haven't noticed any yet ... I'm wondering when I should expect to start seeing some performance issues.
Is this happening just after timed use or after more information gets stored on the drive and less space becomes available?
do it with sanitary erase, find here:
before make a backup and restore after sanitary erase to ssd with superduper or osX new-install and migration afterwards.
(you must connent the ssd to sata in a pc, the only way to get new ssd-condition)
How long to degrade? Difficult thing to answer. It depends how much you write to the drive. My laptop right now has a 128 crucial ssd in it that is only used for os and apps - about 3 months in no real degradation. I have a separate drive for data.
My mini has an ssd in it but i use it to store stuff too - that's quite heavily degraded now.
It really depends on your usage profile. The more you write, the quicker the performance degrades. To put it in perspective however a fully write fatigued ssd will still be substantially faster than a mechanical drive.