In fairness and the scientific principle of seeking facts, today I spoke to the professor who is head of the Dept of Eelctronics and Computer Science at Curtin University, West Australia. I asked if defragging SSDs is good, bad or indiferent. This is his answer:
No you definitely should not defrag SSDs for two reasons.
1. SSDs have a finite number of writes & reads, so defrags reduce the life span of the SSD.
2. The memory is differently oragnized so there is no need for it.
Defragging per se would have no detrimental effects, and in some cases could marginally increase the performance, but it is so small a gain it is not justified in respect of reason #1 above.
So he told you what I told you and what others told you and what I said others would tell you.
While I acknowledge his superior academic background, I am still not totally convinced, because his premise is primarily based on conserving the write/read life of an SSD. And this is definitely an open area of investigation, as shown by this typical blog by Max Schireson entitled: "Debunking SSD lifespan and random write performance concerns." It is found via this link HERE. In part he says:
And so it goes on. Note the reference to sequential writing and relate that to ability of hardware logical flip-flop IC chips to read binary codes once the data is collated.Durability: The short answer is I wouldn’t worry about it.
For applications which are heavy on random writes, you’re OK (meaning a life span of over 5 years) up to about 25 million writes per day per drive, which is nearly double the IO capacity of the fastest hard disk drives.
For sequential write heavy applications (which benefit far less from SSDs), you’re OK (same 5 year life cycle) assuming the application re-writes each block on average no more than once per half hour; the smallest size of the latest fast HDD’s can barely manage this (take a Seagate Cheetah 15k.7 at 300GB for example, which has a claimed sustained write throughput of 171 MBps), and it gets harder as disks get larger.
In summary:
- I am of the opinion that durability is not an issue.
- I strongly suspect there are certain environemnts in which defrag would help ... especially if the right type of defrag application is used. And this warrants further investigation.
I guess you didn't read the comments where someone said:
Assuming a lifespan of 100,000 write cycles per block..
LOL, all the new 25nm ssd drives are rated at 3000 write cycles per block, down from 5000 for the 34nm. Where did you pull the 100k from, SLC memory??
And the author of the article replied:
Yes, I was referring to SLC memory as used in higher end SSDs like the X25E. Completely different story with lower end consumer MLC drives, I’d be very careful about lifespan there.
I guess you're also unaware of Intel whitepapers for drives like my X25-M which talk about over-provisioning the drive to extend the lifespan. They use the 160 GB model as an example and give 29 TB for the expected endurance OOTB, increasing to 68 TB with 16 GB overprovisioning and so on. Most people will just format to maximum capacity, which means that things like hibernation and hybrid sleep can use up the majority of their writes all by themselves. Though pointless, I would guess defragging is less of a concern WRT lifespan because it's done much less frequently than sleeping, and once defragged, files stay defragged. So it would be expected that an initial defragmentation would move a lot of data around, but subsequent ones would move less.
I always recommend disabling hybrid sleep on SSDs unless you really need it, and if you're on a laptop, you don't thanks to the battery, and on a desktop equipped with a decent UPS like my APC XS-1500 running Powerchute, you don't, because the UPS will wake it from regular sleep to hibernate in the event of a prolonged power outage. This saves me 10s of GBs of completely pointless writes per day.
All that said, I'm sure you'll continue to believe whatever you find fun to believe, seize upon speculation and repeatedly present it as facts that support your mistaken beliefs, and hurl some more insults at people who are trying to help you.
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System One
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