

SSD Write Endurance Considered Sufficient - forbes
http://ef.gy/statistics:ssd-write-endurance

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wmf
This is a pretty poor article. Consumers haven't bought SLC in years and MLC
is much less reliable (although the actual reliability of flash is still
higher than the rating). It doesn't take write amplification or any kind of
real workload into account. And it may contribute to the alarmism that it
claims to dispel; at worst your SSD will last 172 days? Yikes!

~~~
jws
Not like magnetic is necessarily immune. WD greens used to have astoundingly
bad spin down logic. I killed a bunch of them with default Linux settings and
near idle servers in about that time frame.

~~~
drzaiusapelord
Greens are not enterprise drives and shouldn't be used in RAID arrays.

Their logic makes perfect sense for single disk and "green" (power saving.)
Its just incredible what people will do to save a little cash on servers. Your
company's data depends on them and you put in the cheapest Best Buy inventory
you can find?

~~~
jws
I'm not sure who you are replying to. Your fictitious account does not match
my reality.

A drive that is accessed a couple times a day seems like the perfect use case
for a green. Sadly, it head parks after 8 seconds of idle time, and Linux was
doing one IO every 30 seconds, I believe as part of the S.M.A.R.T. monitoring
(its been a while), the drive is rated for 300000 head parks in its lifetime,
so in 105 days the drive has thrashed away its specified lifetime because you
were monitoring the drives' health, and head parks wasn't one of the
parameters tracked, so it didn't even help to monitor!

This is not because the Green is not Black. It is not the grade of bearing, or
the balance tolerance of the platters. This is because WD wrote ridiculously
silly firmware for their drives and they self destructed on one of the most
common computing platforms.

Back to the article topic: The similar workload machines I deployed 14 months
ago have an SSD for their root drive and newer greens (tweaked to not load
cycle) for their bulk. None of the SSDs have even reach 1% of their media
lifetime count in their S.M.A.R.T. data. I'm not worried about wearing out
SSDs.

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potkor
People go completely irrational about avoiding writes to SSD's, I've seen
researchers at an EE dept spending evenings tuning their Windows installations
and going as far as stuffing frequently used stuff onto a RAM disk.

I guess the early off brand SSD's randomly eating your data didn't help the
popular perception (even though that wasn't because of flash wear). But
still...

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marshray
What's wrong with locating frequently used stuff on a RAM disk?

~~~
wmf
It's work, but it's unlikely to have any benefit.

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bconway
I remember when SSD's first started hitting the market years ago, everyone's
utmost concern was about wear leveling.

As it turns out, if you ship a drive with buggy firmware and it refuses to be
recognized after the 50th cold boot, write leveling ends up not being so
important.

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lbraasch
tl;dr

I'm guilty of the SSD fear. My first Intel (320) drive was meticulously
maintained in fear of shortened life span and performance losses. I went so
far as to question every file copied to the drive vs. mounting an external
HDD. The thing bricked itself due to a firmware bug in less than 12 months.

Using a Samsung drive now. I don't think about read/writes anymore. I just use
the darn thing.

~~~
threedaymonk
> The thing bricked itself due to a firmware bug in less than 12 months.

Was it an OCZ, by any chance? The exact same thing happened to me. I
scrupulously avoided unnecessary wear, disabled swap (though I've been
disabling swap for years), mounted /tmp on a RAM disk, and the accurs't thing
killed itself stone dead _waking from sleep_ due to a firmware bug.

I also replaced it with a Samsung, as it happens.

~~~
ryanklee
> My first Intel (320) drive

~~~
threedaymonk
Oh, that's embarrassing! I read that, but somehow convinced myself that it was
part of another comment.

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gcp
c't has a lang duration test where it became obvious many SSD's were dying
long before they should according to the theoretical numbers. Unfortunately it
doesn't seem to be available for free: [https://www.heise.de/artikel-
archiv/ct/2012/03/066_SSD-Zerst...](https://www.heise.de/artikel-
archiv/ct/2012/03/066_SSD-Zerstoerung)

This technology is too dependent on software to make these kind of models even
remotely approximate reality.

~~~
65a
Here's a forum doing write tests on a variety of mlc and slc drives...ongoing:

[http://www.xtremesystems.org/forums/showthread.php?271063-SS...](http://www.xtremesystems.org/forums/showthread.php?271063-SSD-
Write-Endurance-25nm-Vs-34nm)

Also, most MLC has between 10k and 1k writes, not 100k. TLC is even worse!

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jbellis
It looks like he's only considering ideal writes with no amplification. This
can make a big difference: <http://lwn.net/Articles/428584/>

~~~
jerf
Considering he's modeling the drive writing at the full SATA 3.0 interface
speed for the entire lifespan of the drive, continuously, amplification
shouldn't affect his numbers, only the perceived throughput the user receives
under this workload. He mentions this is already faster than the drive can
actually write: "the maximum link speed for SATA 3.0, which happens to be
larger than any other relevant interface or drive speed so it's a solid upper
bound."

~~~
tbrownaw
I thought write amplification happened inside the drive (due to the drive
internally working in bigger blocks than the 512-byte sectors it presents to
the outside world), so the amount of data written to flash would be greater
than the amount sent over the SATA link?

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tjoff
I've always wondered what these theoretical numbers, which has been quoted
since long before consumers could ever afford an SSD, should tell you... They
should not, in any way, make you trust your SSD. They are beyond useless.
Also, this article assumes no write amplification and assumes perfect wear
level algorithms. He/She even throws in usb-thumb drives in the mix, so, how
do you know if your thumb drive has a perfect (TM) wear level algorithm? What
about that flash card? Would you recommend storing swap and log files on that
too? Sigh.

Compared to this article the advice of not ever storing swap/log files on a
flash drive would be sound advice.

But yes, you are _probably_ not going to hit the limits of your consumer drive
SSD. But whether you are going to or not you will not, under any
circumstances, be able to find out by making some numbers up. If anyone knows
it is the manufacturer, and you can bet you won't get access to that data.

~~~
twotwotwo
You can use smartctl or equivalent to see the media wear indicator.

But SSD firmware bugs have been a larger problem in practice than wearout, and
MWI won't help you with them; keep backups.

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twotwotwo
SMART says the years-old, low-capacity MLC SSD in this computer is 5% worn
out. SSDs in RAID arrays at work are getting a much heavier workout and
handling it fine.

You can use smartctl or the equivalent to check the media wearout indicator to
see how much the actual workload has worn out a drive. If your computer isn't
constantly writing, you're probably fine--that is, your writes will last until
you'd be upgrading anyway.

But, keep backups. Besides the many practical problems you can have (laptop
lost! fire!), SSDs have firmware bugs every so often.

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saidajigumi
SSD write fear is kinda nuts, IMO. It's a device subject to wear, tear, and
catastrophic failure -- just like HDDs. Keep backups (three for important
data; a cloud copy is only one copy), enjoy the performance, and don't sweat
it. If you aren't keeping backups, then go ahead and cower under the sheets at
night.

~~~
twotwotwo
\- Smartctl has a media wearout indicator if you want to check. Most likely,
you'll check it after months of use, see that you've used like 3% of the write
capacity, and then not sweat it.

\- Firmware reliability sadly has been an issue. So, yes, keep backups.

\- It's fun to check out the ongoing SSD write exhaustion derby here:
[http://www.xtremesystems.org/forums/showthread.php?271063-SS...](http://www.xtremesystems.org/forums/showthread.php?271063-SSD-
Write-Endurance-25nm-Vs-34nm)

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rnovak
Since when do SSD's have a 100,000 write limit? My 256gb Samsung 840 has
something like 2-3k, not 100k.

~~~
wmf
SLC. This article is a blast from the past.

