SSD - To Defrag or not to Defrag

Ok, based on the mis-information that is rampantly thrown about here about the difference between defragging a ssd and not, lets look at the building blocks of ssd.

I have pulled up the specs on one of the chips used in ssd drives. This is not the only chip used, but the technology is very similar between these chips, and the functionality is typically the same, but speeds may vary.
NAND Flash Memory
MT29F2G08AABWP/MT29F2G16AABWP
MT29F4G08BABWP/MT29F4G16BABWP
MT29F8G08FABWP

• Endurance: 100,000 PROGRAM/ERASE cycles - this means the typical 2gb block can be written/erased 100,000 times.
• Page size:
x8: 2,112 bytes (2,048 + 64 bytes)
x16: 1,056 words (1,024 + 32 words)
• Block size: 64 pages (128K + 4K bytes)
• Device size: 2Gb: 2,048 blocks; 4Gb: 4,096 blocks;
8Gb: 8,192 blocks
• Read performance:
• Random read: 25μs
• Sequential read: 30ns (3V x8 only)
• Write performance:
• Page program: 300μs (TYP)
• Block erase: 2ms (TYP)

So, for those of you who 'ASSUME' that defragging will not improve performance, pay attention.

a sequential read at the chip level is nearly 1000 times faster than a random read. now most of the reads on these drives will be sequential, because the data is written that way, but the more fragmented the drive is the more often its going to do a random access vs a sequential access.

So, performance WILL be improved if the drive is extremely fragmented.

BUT, since you have a very finite limit on the number of write/erase cycles, I wouldn't defrag a ssd more than one time, or at the very most very very seldom. (like once a year maybe at most)

Based on this information, I have a ssd for my OS, and I have a IDE drive for my data. And I'll be disabling my windows swap file, or moving it to my IDE Drive.

Another note to extending the life of your ssd, which I'm still researching so I don't have all the answers yet, is that its not defragging thats going to kill the life span, but all your temp files.

Windows Temp directory, Cache files, browser history files etc.. I'll be looking into mapping these to my IDE drive so that my SSD doesn't get written/erased every time I clear my cache and history files. But that will have to be another thread I believe.

It appears that most of the people on this forum here have computer certifications, but very few appear to have electronic component backgrounds. And for this you need to have some exposure to the actual components.

Non-Volatile memory, ie.. flash memory has extremely finite write/erase cycles, normally 1000 cycles per block, and historically is used for ROM not RAM type applications. An SSD is a RAM application, and therefore everyone here is correct in that your SSD will have a very short life span if you're not paying real close attention to the number of write/erase cycles of the components.

According to the specs I posted in a previous post, even the chip I selected has a 1000 limit to the number of block write/erase cycles. Which is an extreme limit for a RAM type application. Please note, that chip manufactures guarantee that the chip can be written/erased 1000 times, and that it will take a minimum of this number of write/erase cycles. So the actual number before failure will be more than that minimum, but they do not state how many more, and do not guarantee more than the 1000.

As far as which chip is used on your SSD, and if there are a different number of write/erase cycles per block, I don't have that information. But, to date I have not seen a single non-volatile ram chip which has more than 1000 write/erase cycles per block. I will be looking for more information on this subject. And will post additional information as I find it.

That all being said, I am not nearly as interested in maximizing my performance, ie using diskpart etc.. as I am in extending the life of my SSD, so I really don't care if its 22uS slower reading because I didn't use diskpart.

defrag should only be used on hdd or ide drives, ssd drives don't need it because it doesn't make a difference and shortens the drives life

mine won't even let me do it. doesn't give me the option. it shows it on the screen, but will only let me defrag the hhd

do not defrag an ssd

ranmn7 said:

Ok, based on the mis-information that is rampantly thrown about here about the difference between defragging a ssd and not, lets look at the building blocks of ssd.

I have pulled up the specs on one of the chips used in ssd drives...

So, for those of you who 'ASSUME' that defragging will not improve performance, pay attention.

a sequential read at the chip level is nearly 1000 times faster than a random read. now most of the reads on these drives will be sequential, because the data is written that way, but the more fragmented the drive is the more often its going to do a random access vs a sequential access.

So, performance WILL be improved if the drive is extremely fragmented.

BUT, since you have a very finite limit on the number of write/erase cycles, I wouldn't defrag a ssd more than one time, or at the very most very very seldom. (like once a year maybe at most)

The paragraph that performance will be improved when extremely fragmented appears on the face of it to contradict the paragraphs immediately before - much slower random vs. sequential access - and after, i.e., why defragment a drive that's extremely fragmented if that's the best performance? What am I missing?

I should add that after 2-3 months a then recently-purchased Corsair Force 3 60gb SSD seemed to slow considerably and defrag changed that immediately.