Re: FAQ's on solid-state drives


Quentin Christensen
 

Good points Joseph,

Just to expand on the "what should I store on SSDs" point a little:
As SSDs tend to be much more expensive and smaller than traditional
HDDs (you can buy a 2 Terabyte conventional hard drive for less than
the cost of a 240 Gigabyte (a quarter of 1 terabyte, or just under),
the idea is to put your most frequently needed and accessed files on
the SSD and if you need more space, use a conventional HDD.

So for instance, you might install Windows itself onto the SSD - that
will improve how quickly it loads and works, but then keep your music
collection on a traditional hard drive.

Documents, well could go either way - it depends on how many / how big
they are. Ideally the best solution is to have one system drive with
Windows etc on it, and one separate drive with all your own data on it
- that can make backing up and upgrading easier, and of course if you
are searching for a document, you know you don't need to go near the
system drive to find it then.

Programs again, if you have something that will fit and that you use
often, you could put it on the SSD definitely.

And finally with the concern around SSDs failing, it's important to
remember that traditional hard drives fail too so whatever you use,
ensure you have a backup. Windows 10 has quite a painless backup
system, but if you want a third party alternative, there are plenty
around. Just be sure that whatever system you use, you know what it
is backing up and what it ISN'T backing up and how to restore things
down the track if you need to.

Kind regards

Quentin.

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On 12 January 2016 at 03:55, Joseph Lee <joseph.lee22590@gmail.com> wrote:
Hi,

First, a warm welcome to our new friends. We hope you learn something new
about Windows 10 on this forum.

Here are some FAQ’s regarding SSD’s (solid-state drives). As a user of SSD’s
myself, I do find that it improves responsiveness, and since I have a hard
drive also, I can compare characteristics of these two.



Q. What exactly is a solid-state drive?

A solid-state drive (SSD) is a storage device that stores data
electronically. Traditionally, a hard disk drive (HDD) stores data on
magnetic disks that spins rapidly. A device called read/write head (a very
thin magnet suspended in the air) scans the magnetic surface of spinning
disks, reads data and writes new data. In contrast, a solid-state drive uses
flash memory (a type of electronic memory cell/window) for data storage, and
a small computer inside the drive called a drive controller acts as a data
placement manager. All data reads and writes are done electronically (does
not involve spinning disks anymore), and this operation is many times faster
than spinning disks.



Q. Does Windows 10 recognize SSD’s?

Yes. Once an SSD is detected, the following services are disabled:

· ReadyBoost

· Defragmentation (on SSD’s only; they use a completely different
way to manage data deletion).



Q. Is it true that SSD’s have limited life cycle?

In the old days (around 2008 or so), SSD’s promised limited storage
endurance. This is changing, and newer drives such as Samsung Evo 850 and
newer Intel drives are smarter when it comes to data storage management,
thus extending the life of these drives.



Q. I kept hearing about this thing called “trim”. What is it and how does it
work?

SSD’s, like flash drives, are good at reading from anywhere in the drive but
cannot cope well when data are written and deleted frequently. In order for
new data to be written, the drive controller will first check if there are
free areas on the disk (called sectors; technically called pages) that is
large enough to hold incoming data. If it cannot find it, something must be
sacrificed in order to make new room, and the object of sacrifice is
existing data. The “sacrifice” is first moved to a temporary area, the page
where incoming data will be stored is cleared, and the evicted data,
together with the new bits are written back to the flash memory.

Think about this for a moment: whenever you add or delete files on an SSD,
the drive is forced to do this operation many times. Combined with limited
life cycle of old drives, this would result in shorter and shorter life
cycle, and eventually the drive will stop working (more on this in a
second). A solution does exist to mitigate this somewhat: called “trim”,
this operation requires a careful coordination between an operating system
(system programs) and the drive. Basically, an operating system such as
Windows 10 will keep a record of what’s on a drive (called a file system),
thus it can track which files were added and deleted. In case of hard disks,
all file systems care about is data in specific sectors; for SSD’s, they
need to keep track of pages that files occupy (at least, data in files). The
trick here is that it is faster to write to empty pages (when viewed from
drive controller’s perspective), and knowing that, file deletion is
interpreted by SSD’s as a command to trim (delete data from) cells used to
hold data from the just deleted file, thereby letting the drive use the
freshly reclaimed area for new files. Without trim, the drive and the
operating system (in our case, Windows 10) will become out of sync quickly:
Windows sees that you’ve deleted a file, but the drive will claim that
something is “occupying” the location where data from the just deleted file
used to reside, thus it’ll slow down SSD’s performance next time something
needs to be written to that particular location.

By default, Windows 7 and newer supports trim, although Windows 7 didn’t say
the drive is being trimmed (this came with Windows 8 and later). Also, newer
drives lets Windows see that they support trim, and without this, Windows
cannot use trim properly (in this case, one needs to use drive-specific
manager such as Samsung Magician).



Q. Which data should I keep on SSD’s?

Certainly you shouldn’t mess with system files stored on SSD’s, but you can
move your documents and other libraries to somewhere else.



Q. Can I remove so-called page files from an SSD?

No. This is intimately tied to a trick Windows and other operating systems
use to manage memory. Called “virtual memory”, this lets programs see more
memory than what the computer can provide (although installing more RAM is
better in the long run). This is achieved by using a file on a hard disk (or
SSD’s) as though it is RAM when it is not.

Basically, while a program is running, Windows and other operating systems
keeps an eye on how much memory a program is using. If Windows finds that it
needs to run a new program and if space on RAM (random-access memory, the
physical memory on your computer) is tight, Windows (and others) will take
action by removing something off physical memory. Since programs require
data to be present in RAM, Windows will move data or program code to
somewhere else that isn’t RAM but is treated as such: a page file.

Now suppose a program is running and it needs to read something from memory,
and it happens that the data it needs “isn’t there” on physical memory. If
Windows is notified of this, Windows will consult the page file to see if
the thing the program needs is located there and will bring it back to RAM.
If memory becomes tight thanks to this operation, Windows will choose
something else to move to page file (many programmers and researchers spent
decades perfecting this operation; to resident programmers (including I),
this is called “page replacement algorithms”).

Thus, you shouldn’t remove page files (or disable them unless told to do so
by reputable sources). One way to save SSD space is shrinking page file size
(at least on my system, my page file size is 200 MB (way less than RAM
capacity I’ve got), safely configured via Samsung Magician).



Q. Can I be notified if my SSD is failing?

Yes and no. Many SSD’s will let an operating system (such as Windows 10)
know when it is about to fail, giving you a chance to make a backup of this
drive. However, the way an SSD fails is quite subtle: you might be doing
something and the drive will click, and that’s it.



Q. I keep hearing about a drive called “hybrid drive”. What is it?

A hybrid drive (officially called “solid-state hard drives”) is a
traditional hard disk with some SSD storage added on top. To the user, a
hybrid drive appears to be a spinning disk, but inside, a SSD is used to
store most commonly accessed data. This is used in many places, including
speeding up boot performance (it is faster to read from this SSD module than
from a spinning disk).



References:

· Solid-state drive (Wikipedia):
https://en.wikipedia.org/wiki/Solid-state_drive

· CNET, March 1, 2013. Digital storage basics, Part 4: SSD
explained:
http://www.cnet.com/how-to/digital-storage-basics-part-4-ssd-explained/

· What is the TRIM function for solid state disks (SSDs) and why is
it important (Windows IT Pro):
http://windowsitpro.com/systems-management/q-what-trim-function-solid-state-disks-ssds-and-why-it-important



Cheers,

Joseph

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