Trainz defrag ?

G'day, it's OK if you are running conventional hard drives but don't defrag solid state drives as they don't need it and it will shorten there life.
Regards
Barrie
 
Hi Barrie:

Would you please explain why SSD's don't need defragging and if you do it might shorten it's life? There are no moving parts inside.

Thanks,

Ben
 
I can explain that one.

SSDs contain memory chips (like USB keys) with a limited amount of read/write cycles. Each time a defrag is done, it wastes some of these cycles and shortens the lifespan of the drive.

Shane
 
Hi Barrie:

Would you please explain why SSD's don't need defragging and if you do it might shorten it's life? There are no moving parts inside.

Thanks,

Ben

An SSD benefits from being heavily fragmented by design. Lets give an example.

With a HDD a single read head needs to track across the platters and read each item of data one by one. With an SSD, having data spread onto multiple flash chips which can all be read from at once significant increases performance. Defragmenting an SSD therefore can decrease performance since each piece of data can now only be read one at a time from a single flash chip. It's the activity of moving data and writing it to a different flash chip that decreases lifespan.

Jack
 
Hi Shane:

I've worked in electronics for over 50 years and even spent 5 years at a company making transistors and I've never heard of one having a limited number of cycles (from off to on for example). After all a computer chip is little more then a massive collection of transistors (with some other items deposited on the substrate) interconnected however the manufacture wants. Where do these "cycles" come from?

Hi Jack:

Now I see one of the ways the speed is increased.

Thanks gents,

Ben
 
It's all to do with the way data is written - I know that SSDs normally specify how many times they can be read/written to.

However, there is a method in Windows 7 and later (TRIM) that can be used to optimise SSD drives.

Shane
 
Hi Shane:

I've worked in electronics for over 50 years and even spent 5 years at a company making transistors and I've never heard of one having a limited number of cycles (from off to on for example). After all a computer chip is little more then a massive collection of transistors (with some other items deposited on the substrate) interconnected however the manufacture wants. Where do these "cycles" come from?

Hi Jack:

Now I see one of the ways the speed is increased.

Thanks gents,

Ben

Ben,

SSDs are basically a modern version of EEROMs. :)

We used to use a special burner to setup the EEROMs for the equipment I was testing and repairing. The chips in those days were a lot slower, i.e. 28ms instead of the ns speeds we see today. The chips are written at a higher voltage and read at another. The very act of writing the data changes the substrate to hold the data. Writing too much in the same place will eventually degrade or kill the cells where the data is written. The same process works today albeit with much smaller voltages and everything is higher speed.

By using special algorithms in the SSDs onboard BIOS located on the controller, on the same PCboard inside the case of some drives, the devices utilize scatter-gather technology to spread the data writes over various cells instead of concentrating all the data in one place. By defragmenting an SSD, you are actually also defeating the purpose of this technology as well as degrading the unit because of the continuous writes to the cells.

Since there are no moving parts, there is no reason to defragment the SSD unit as the data is read back, though much slower than DRAM chips, much faster than any platter-type hard drive could ever be. Defragmenting works on platter drives because the drive heads are mechanically moved around to read the data, and by placing the data bits close to each other, there is less head movement, which makes the overall read process faster.

I hope this explains things...


Getting back to the OP's question, yes, defragging really helps if you are doing a lot of work in CM and importing and fixing data.


John
 
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Hi John:

Now I get it. I know what you are talking about having fiddled with them years ago and yes they have a finite lifetime (but better then Eproms where you had to blow the fusible links to program them). It isn't true RAM - its electrically alterable read only memory which isn't entirely the same thing. Its advantage is maintaining data when the power is off. True RAM can't do that unless there is something new of which I am unaware (and there might be).

So if you buy one what do they tell you about the expected lifetime (in human terms)?

Ben
 
So if you buy one what do they tell you about the expected lifetime (in human terms)?

Ben

SSD's are rated in gigabytes written per day over so many years. An example would be my Crucial MX100, which is rated for 20GB's per day over 5 years I believe? In normal use terms, they will last an eternity.

Jack
 
I wonder how that translates to an individual cell (or whatever they are called). Does every read (or write) cycle very slowly degrade an individual cell or is it somehow cumulative over the entire substrate? Not that it matters in anyone's lifetime unless they are Methuselah.:hehe:

My computer automatically defrags all drives (internal and external) once a week (or the drives do it themselves - I'm not certain one way or the other). Guess I'll have to figure out how to turn that off on a SSD when the time comes.

Ah well - enough of this - thanks for the replies - back to making the Age of Steam RH & TT.

Ben
 
Just one more thing before you close the theme of SSD's. Reduce your paging file to zero, and as it is being said, never defrag.. And everything will be alright. later in life, when you can, upgrade to M2.0 and be amazed of speed.
 
It also depends upon the quality, which of course is getting better every day for the consumer-level storage. For those big corporate servers, the SSDs are rated at 265,000 hours MBTF (Meantime between Failures.). We don't see that level for the ones we can afford by they are getting better.

If your defrag software is "smart" it will automatically ignore SSDs, or you can configure it not to touch specific drives and directories, which I have done to ensure mine never gets touched.

John
 
I did already a defrag . It took the whole night .

I build a brickwall fence round specific drivers .
 
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