Fragging wonderful: The truth about defragging your SSD

With smarter file systems and faster disks and PCs, file fragmentation isn’t the performance suck it once was. Older computers had a habit of splitting files and spreading the parts all over your hard drives, but modern ones don’t do this as much. Not even close. That said, a bimonthly pass with a capable defragger can help you maintain peak performance on a heavily used hard drive.

However, solid-state drives, which use flash memory instead of a hard-drive platter to store data, are another story: My tests showed little or no benefit from running a number of disk defragmenters on a heavily used SSD.

Conventional logic dictates that you should never defrag an SSD, because the SSD controller writes data in a scattershot-fashion to multiple NAND chips and locations, using algorithms that only the controller understands. The operating system sees it as a hard drive with sectors, but the data is spread all over the drive by the controller. Defragging these “sectors” is like trying to assemble a jigsaw puzzle blindfolded: You can feel parts of the pattern, but you can’t see the whole picture. In addition, NAND is good for only a few thousand write cycles, so defragging can reduce the SSD’s lifespan by unnecessarily writing data to it.

Despite those arguments, at least four defragging utilities purport to increase SSD performance through optimization: Auslogic’s Disk Defrag Pro, Condusiv’s Diskeeper, Raxco’s PerfectDisk, and SlimCleaner Intelligent Defrag. To understand how these might be of benefit, let’s review a few facts.

Used NAND cells (the parts of flash memory that holds the data) must be erased before they can be written to.

Early SSDs put off erasures, simply marking cells as no longer used when you deleted a file. When fresh cells ran out, having to erase the marked/used cells before rewriting to them slowed performance.

The advent of the TRIM command, which invokes a drive’s built-in garbage collection routines (including erasing unused, previously written cells), solved the problem.

Windows 7 and Windows 8 support the TRIM command.

If you read the documentation used to support most SSD optimization claims, you’ll notice that much of it predates Windows 7 and the TRIM command. Before that, free-space optimization could force an SSD into garbage collection and thereby regain lost performance. But on a modern SSD running with a modern operating system, many of these optimizations are no longer needed.

The issue: When I investigated, no SSD vendor would state unequivocally that the defragging programs would or wouldn’t benefit a modern SSD running on a modern TRIM-supporting operating system. I could find no hard evidence anywhere I looked, so I decided to gather my own....

Read more at: Fragging wonderful: The truth about defragging your SSD | PCWorld


See also: How to Use "Optimize Drives" to Defrag HDD and TRIM SSD in Windows 8 and 8.1

 

[Coram Daes]

Which is not what I am talking about. I am addressing storage capacity as still being an issue.

Defrag stuff apart.

 

[HerrKaLeun]

Because SSD are not mainstream yet.[/B] To me, SSD is still a new technology, emerging in usage as prices for the drives goes down. There is still too much of a price difference for server drives and desktop drives with higher storage volumes in order to start yelling about mainstream.

They are pretty much mainstream for OS. $100 gives you all you need. For data you use a spinner, and with W7/8 defragmentation is not a noticeable issue anymore.

About 3 years ago viable and inexpensive SSD were available, which is ages in computer-time.

And even for someone who doesn't want to afford one, the fact that defragging is not needed is general knowledge, and has been to anyoen just reading about SSD in the past 3 years.

 

[Coram Daes]

I agree that the OS may reside on an SSD and gain performance by it. I also agree that the SSD capacity and price is not really an issue when we are talking about OS allocation. Today.

I do NOT agree SSD's were cheap even three years ago. I do NOT agree that the knowledge about not having to defrag SSD's was common spread three years ago, and hence I do NOT agree to most of what you write, also in a pretty condescending tone.

Anyone can claim "hey we all knew that" without being able to present any facts to the matter. I do not.

I am ALSO saying that optimizing SSD's is a technology that may or may not hit the market, depending on if research may find a way to do so. That is beyond any of us, but we already see a valid tech in use for optimizing SSD storage, the one mentioned earlier, TRIM. I am not saying that is defrag, as we interprete it historically, I am only saying it is some kind of optimization. That is undeniable.

Also, what you seem to forget is that with any computer that have several drives attached to it, the overall performance of that computer is not deemed by the OS boot time alone, or of the R/W operations on the OS disk, but of the disk access needed for the computer/server in question to perform its role. In that case you may very well have an SSD as OS disk, but SAS or SATA drives as storage/work space and the overall speed of the computer will not be largely enhanced, only because the OS resides on an SSD.

 

[jimbo45]

Hi there
I posted some issues on how the I/O actually works on OS'es like windows - if one reads this then the whole concept of "Long File chains" etc are essentially irrelevant to the whole issue -- anyway just to re-iterate.

Most modern OS'es - especially Apple Ios, Windows 7 / 8 / 8.1 the actual I/O is performed where possible ASYNCHRONOUSLY with your work. The OS'es use a complex algorithm (which is optimized the more you use the OS) known as PRE-FETCHING.

What this means in plain English is that the OS can make a pretty good guess as to what data you are likely to use next and for example while you might be typing a reply to the Forum the Pre-fetch routine has already retrieved some data and stored it in the Disk Cache so when you need it the I/O doesn't need to be done as the data is already available.

These algorithms while complex are usually pretty good and this is where the design of the Disk is important -- the size of the CACHE needs to be large enough so the OS can PREFETCH a reasonable amount of data whith a good probability of getting a good hit -- I.e it has made a decent guess.

Going into complex statistical analysis here is way beyond the scope of this post - but these algorithms are pretty smart these days.

Particularly in the case of things like OS'es -- where the main data doesn't actually change too much -- the non persistent data like work areas and page data don't need to be saved permanently on Disk at all.

DEFRAG for an OS -- especially where the OS has been moved to it's own partition isn't really necessary AT ALL - and hasn't been for a long time -- assuming you have decent spinners and the disk has a decent cache. Any 7200 RPM disk is probably OK to ignore defragging.

5400 RPM disks are usually JUNK anyway so even if you DID defrag them you would still be twiddling your thumbs waiting for I/O most of the time. These disks should you still be unfortunate enough to have any are best left for data that's usually only READ like multi-media files or backup / archive.

SSD's are different and having no mechanical parts can react a lot quicker -- PREFETCH is still worth while on these but data access is an order of magnitude faster so they can operate with smaller caches - to make them cheaper.

There's a whole slew in this issue which consists of more than just "Long file chains". - I wonder if the makers of these products actually understand how the OS actually works.

The best you can do for any system is to PUT THE FASTEST DISKS INTO THEM. Slow I/O will kill any system stone dead - even if you have an I7 processor.

Anyway my last word on this - I can honestly say I don't think I've EVER noticed a miniscule of improvement after defragging a disk -- replacing a slow one with a faster one with a bigger cache -- that's another story - and an SSD is best of all.

Cheers
jimbo

 

[LittleJay]

Anyway my last word on this - I can honestly say I don't think I've EVER noticed a miniscule of improvement after defragging a disk -- replacing a slow one with a faster one with a bigger cache -- that's another story - and an SSD is best of all.

I'll second that. :thumb:

 

[HerrKaLeun]

Jimbo45: excellent analysis and explanation!

 

[Hopachi]

For speed improvement, Defragging was useful on Win98, on fat32. Since ntfs, defragmenting didn't gave a significant boost anymore.

I never defragged on 7200rpm spinners for speed and now there's no way I'm defragging on SSD.

The only time I find defragmenting useful (for spinners only, but might apply for SSD as well) is when you want to shrink down a partition but it's not giving enough space for this because of fragmentation (files chunks are spread up to the end of disk). You most likely need to defrag the disk first. If you use one or two good programs (some like the free Defraggler) that also give the names of the files needed to defrag, you can get there copy/move or delete the files: pagefile.sys cannot be defragged because is unmovable so you might wanna disable it first (even delete it manually afterwards), defrag the disk now, shrink down the partition after defrag, when all is good and then re-enable the pagefile again. There are cases when this steps are required, if you have small and/or full disks. Usually if there's enough space on the disk, you will be able to shrink the partition enough without defragmenting, but again, hopefully there are no pagefile pieces in the way of the shrink operation.

On a daily usage, no defrag is really required, if the disk has very large files stored then there's a higher chance for those to be fragmeneted (split into smaller pieces) of course.

 

[lehnerus2000]

I used to find that XP ran better if it was properly defragged.

I can't say that I notice any real performance improvement in W7 after defragging.
It might shave a few milliseconds off of operations (thus unnoticeable).

 

[Coram Daes]

I am not even sure we are talking about the same basic tech anymore.

Granted Jimbos post makes a lot of sense from that perspective, but is not really what I was addressing or responding to.

 

[DooRules]

It certainly has been common knowledge that you do not need to defrag an ssd for years. Just because you didn't know that doesn't change the facts.

Trim is not anything like defrag, neither is GC. Both trim and GC are run at the controller level and require no input from the user.

There is no need to "optimize" any modern ssd. They are plug and play, just like any spinner drive.

 

[jeffrys]

"Sure, lower capacity SSD drives 128GB and 256GB are rapidly decreasing in price, but for 0,5 TB drives and above you are still sweating it at around and above 4 times the price compared to a SATA HDD.

A 500GB HDD will cost you about $60 at Amazon

A 500GB SSD will cost you about $300 or above..."

True Coram, but in order to have your HDD fast, not only do you need to defrag it, but keep in mind that when using 60 % (or more) of the disk capacity your performance will degrade. You do not have that with a SSD.

HDD are nice for static data and.....that's it.

Jeff

have to edit this:

" I do NOT agree that the knowledge about not having to defrag SSD's was common spread three years ago,"

BUT IT WAS. I use SSD's from the take off, i guess some 5-6 years ago. My first buy where 6 OCZ (their first make) and already then it was common sence NOT to defrag a SSD.

Jeff

 

[jimbo45]

"Sure, lower capacity SSD drives 128GB and 256GB are rapidly decreasing in price, but for 0,5 TB drives and above you are still sweating it at around and above 4 times the price compared to a SATA HDD.

A 500GB HDD will cost you about $60 at Amazon

A 500GB SSD will cost you about $300 or above..."

True Coram, but in order to have your HDD fast, not only do you need to defrag it, but keep in mind that when using 60 % (or more) of the disk capacity your performance will degrade. You do not have that with a SSD.

HDD are nice for static data and.....that's it.

Jeff

have to edit this:

" I do NOT agree that the knowledge about not having to defrag SSD's was common spread three years ago,"

BUT IT WAS. I use SSD's from the take off, i guess some 5-6 years ago. My first buy where 6 OCZ (their first make) and already then it was common sence NOT to defrag a SSD.

Jeff

Hi there @ jeff

Don't want to keep labouring the point but modern spinners DO NOT NEED TO BE DEFRAGGED -- you basically for the domestic market have 5400 RPM and 7200 RPM drives -- 10,000 RPM SCSI expensive drives etc are usually specialized server stuff so we'll concentrate on the Domestic stuff.

1) 5400 RPM disks are so slow anyway that the performance is just going to be horrible whatever you do and anything short of replacing the drive will not yield any user perceptible performance.

2) OS data doesn't change much - most non persistent data is in the page area and scratch data which get re-initialized every time -- unless you run your disks 95% full no defragging will help in optimising these OS areas.

3) User data is essentially READ ONLY (in general) such as music / multi-media so it doesn't really benefit from any defragging - the rate for example at which Music is played on your audio card is far slower than even HORRIBLE disks so you won't get an I/O penalty here.

4) I've explained how basic OS I/O works in previous posts and how it's overlapped with processing and the concept of PRE FETCHING -- any 7200 decent spinner will perform adequately - 5400 one's won't - simple END OF STORY. Always have your OS separate from DATA partitions.

5) SSD's will always improve ANY system.

6) Bottleneck on the OS is usually caused by POOR disk I/O (5400 RPM devices) - and running too many apps with insufficient RAM -- NONE of this will be improved to any perceptible degree by defragging.

If you are running online servers / web sites where users can make queries on DB's then you MUST HAVE FAST DISKS.

Anyway in all this not ONE person has even posted on what sort of performance you SHOULD expect by defragging a disk so IMO the whole question is largely irrelevant anyway.

You can still improve performance on Desktop type systems by having the OS age and Scratch work areas on a different device to the OS (unless the OS is an SSD - I/O is fast enough on SSD's to have the page data etc on the OS disk.

Also rule nr one -- DUMP any 5400 RPM spinner - or just use for backup and archive.

Cheers
jimbo

 

[lehnerus2000]

I thought that I read somewhere that "Wear Leveling" isn't as effective if you don't have free space on your SSD.

 

[CountMike]

Let me ad couple more drops of fuel on the fire. Large data base program and MS Office (at least) intentionally leave some space free for files that are continually growing as the amount of data in them is expanded and so increase reading and writing speed. Such space looks like it is fragmented and defragmenting and solidifying such space can actualy slow them down.

 

[Mystere]

Let me ad couple more drops of fuel on the fire. Large data base program and MS Office (at least) intentionally leave some space free for files that are continually growing as the amount of data in them is expanded and so increase reading and writing speed. Such space looks like it is fragmented and defragmenting and solidifying such space can actualy slow them down.

That hasn't been true for well over a decade, since the inclusion of Sparse file support in NTFS.

 

[crawfish]

I thought that I read somewhere that "Wear Leveling" isn't as effective if you don't have free space on your SSD.

The tl;dr version is to leave 25% free to keep performance high. With TRIM, you don't even to leave space unpartitioned.

AnandTech | Exploring the Relationship Between Spare Area and Performance Consistency in Modern SSDs - Print View

 

[lehnerus2000]

Thanks crawfish

I thought that I read somewhere that "Wear Leveling" isn't as effective if you don't have free space on your SSD.

The tl;dr version is to leave 25% free to keep performance high. With TRIM, you don't even to leave space unpartitioned.

AnandTech | Exploring the Relationship Between Spare Area and Performance Consistency in Modern SSDs - Print View

Thanks for that link crawfish.

 

[jeffrys]

Well Jimbo,

you might be right, but i always had to defrag my HDD's, but that was 6 years ago, before i switched to SSD's.

I never used SATA drives until SSD's came along, always used SCSI drives with a Raid card.

So no, i do not have exerience with Win 7 or Win 8 on HDD's.

Jeff