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List: dng
Subject: Re: [DNG] SSD Lifetime?
From: Didier Kryn <kryn () in2p3 ! fr>
Date: 2023-12-05 9:12:01
Message-ID: a8dd8265-da36-448e-b302-c96c79de5c99 () in2p3 ! fr
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Le 05/12/2023 à 09:09, Martin Steigerwald a écrit :
> terryc - 05.12.23, 04:18:40 CET:
>>> I put a Western Digital Black NVME 500G drive in my desktop system
>>> and ran it for about 3 years. At the end it had 65% life left which
>>> surprised me as my desktop doesn't do an awful lot of disk writing or
>>> even reading.
>> How did you determine this lifetime?
>>
>> I have a couple of systems with SSDs. One is /Everything and the other
>> has two under / and /home. They were rolled out about two years ago.
>>
>> FWIW HowToGeek on testing SSDs claims Blackblaze claims SSD. will
>> outlast HDDs. Samne rate of failure under 3 years and HDDs start
>> failing after 54 years, but SSDs go on further
> smartctl -x on a Samsung 980 Pro 2 TB SSD which is about 2 years
> meanwhile, in daily usage:
>
> Available Spare: 100%
> Available Spare Threshold: 10%
> Percentage Used: 1%
> […]
> Data Units Read: 261.509.276 [133 TB]
> Data Units Written: 73.925.789 [37,8 TB]
>
> Especially in case you leave some space free, use trimming either by
> fstrim or in case its cleanly supported by your SSD with discard mount
> option, preferably async discard like in XFS or with discard=async in
> BTRFS, good SSDs should last a very long time. Of course you can still use
> "noatime" and using a new enough kernel also "lazytime". I just use
> "lazytime" nowadays on my laptops. Together with sysctl setting
>
> vm.dirtytime_expire_seconds = 7200
>
> so it updates every 2 hours instead of AFAIR 24 hours in case of no other
> activity triggering an update.
>
> "Percentage Used: 1%" basically means 1% of the usable lifetime has
> expired by vendor estimate:
>
>> The wear level is given by the “Percentage Used” field, which is
>> specified as (page 184):
>>
>> Percentage Used: Contains a vendor specific estimate of the percentage
>> of NVM subsystem life used based on the actual usage and the
>> manufacturer’s prediction of NVM life. A value of 100 indicates that
>> the estimated endurance of the NVM in the NVM subsystem has been
>> consumed, but may not indicate an NVM subsystem failure. The value is
>> allowed to exceed 100. Percentages greater than 254 shall be
>> represented as 255. This value shall be updated once per power-on hour
>> (when the controller is not in a sleep state).
> https://unix.stackexchange.com/questions/652623/how-to-evaluate-the-wear-level-of-a-nvme-ssd
>
> Due to the way flash works the best way to keep them alive for a long time
> is: Use a bigger capacity than you need and leave some space free. With
> LVM I usually just do not allocate about 10-20% of the capacity. But even
> if you allocate all of the space for filesystems… I am not worried about
> SSD lifetime regarding wear leveling. Not at all. I did not see any of my
> SSDs failing due to wear leveling issues. Not even close. Even with write
> heavy systems like a Plasma desktop with PostgreSQL based Akonadi and
> desktop search and all kinds of writing around here and there.
>
> On any of my laptops I would not even consider putting in a hard disk to
> save SSD lifetime. And if I had a desktop computer, I probably would not
> do either. I love totally quiet systems, happily using zcfan on my
> ThinkPad laptops. And since I use SSDs I noticed how loud even 2,5 inch
> hard disks can be. I still use those for backup purposes, cause even with
> today's low SSD prices for backups I prefer even cheaper hard disks. But a
> 12 TB 3,5 inch hard disk monster in my living area or office? Not even a
> chance.
Congrats Martin; you seem to have some expertise in filesystems and
how to trim them. Unfortunately this isn't very common, and not my case
:~). I used to always specify the noatime option, because I have no
application relying on file access time. Have you any such application
installed?
I noticed your sysctl command, which, I guess, sets the lifetime of
data in the VFS buffers before they are actually written to disk. It is
also available in /proc/sys/vm/dirtytime_expire_seconds and is set to
43200 in my laptop. What is the goal of reducing it to 7200?
What does mean the line "Percentage Used: 1%" in your diagnostic
listing? Cause if only 1% of the disk is used, it should last longer
than if 99% was used, but not many people can afford disks 100 time
bigger than their storage need.
You also talk about the noise of a monster spinning disk used for
backup, but the recommendation for a backup disk is to *not* let it
powered all the time. I've read that a spinning disk used rarely is
considered the most resilient backup storage, in contradiction with SSDs
which loose data if they aren' t periodically powered.
Thanks.
-- Didier
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<div class="moz-cite-prefix">Le 05/12/2023 Ã 09:09, Martin
Steigerwald a écrit :<br>
</div>
<blockquote type="cite" cite="mid:1896672.tdWV9SEqCh@lichtvoll.de">
<pre class="moz-quote-pre" wrap="">terryc - 05.12.23, 04:18:40 CET:
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">I put a Western Digital Black NVME 500G \
drive in my desktop system and ran it for about 3 years. At the end it had 65% life \
left which surprised me as my desktop doesn't do an awful lot of disk writing or
even reading.
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
How did you determine this lifetime?
I have a couple of systems with SSDs. One is /Everything and the other
has two under / and /home. They were rolled out about two years ago.
FWIW HowToGeek on testing SSDs claims Blackblaze claims SSD. will
outlast HDDs. Samne rate of failure under 3 years and HDDs start
failing after 54 years, but SSDs go on further
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
smartctl -x on a Samsung 980 Pro 2 TB SSD which is about 2 years
meanwhile, in daily usage:
Available Spare: 100%
Available Spare Threshold: 10%
Percentage Used: 1%
[â¦]
Data Units Read: 261.509.276 [133 TB]
Data Units Written: 73.925.789 [37,8 TB]
Especially in case you leave some space free, use trimming either by
fstrim or in case its cleanly supported by your SSD with discard mount
option, preferably async discard like in XFS or with discard=async in
BTRFS, good SSDs should last a very long time. Of course you can still use
"noatime" and using a new enough kernel also "lazytime". I just use
"lazytime" nowadays on my laptops. Together with sysctl setting
vm.dirtytime_expire_seconds = 7200
so it updates every 2 hours instead of AFAIR 24 hours in case of no other
activity triggering an update.
"Percentage Used: 1%" basically means 1% of the usable lifetime has
expired by vendor estimate:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">The wear level is given by the "Percentage \
Used" field, which is specified as (page 184):
Percentage Used: Contains a vendor specific estimate of the percentage
of NVM subsystem life used based on the actual usage and the
manufacturer's prediction of NVM life. A value of 100 indicates that
the estimated endurance of the NVM in the NVM subsystem has been
consumed, but may not indicate an NVM subsystem failure. The value is
allowed to exceed 100. Percentages greater than 254 shall be
represented as 255. This value shall be updated once per power-on hour
(when the controller is not in a sleep state).
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
<a class="moz-txt-link-freetext" \
href="https://unix.stackexchange.com/questions/652623/how-to-evaluate-the-wear-level-o \
f-a-nvme-ssd">https://unix.stackexchange.com/questions/652623/how-to-evaluate-the-wear-level-of-a-nvme-ssd</a>
Due to the way flash works the best way to keep them alive for a long time
is: Use a bigger capacity than you need and leave some space free. With
LVM I usually just do not allocate about 10-20% of the capacity. But even
if you allocate all of the space for filesystems⦠I am not worried about
SSD lifetime regarding wear leveling. Not at all. I did not see any of my
SSDs failing due to wear leveling issues. Not even close. Even with write
heavy systems like a Plasma desktop with PostgreSQL based Akonadi and
desktop search and all kinds of writing around here and there.
On any of my laptops I would not even consider putting in a hard disk to
save SSD lifetime. And if I had a desktop computer, I probably would not
do either. I love totally quiet systems, happily using zcfan on my
ThinkPad laptops. And since I use SSDs I noticed how loud even 2,5 inch
hard disks can be. I still use those for backup purposes, cause even with
today's low SSD prices for backups I prefer even cheaper hard disks. But a
12 TB 3,5 inch hard disk monster in my living area or office? Not even a
chance.
</pre>
</blockquote>
<p> Congrats Martin; you seem to have some expertise in
filesystems and how to trim them. Unfortunately this isn't very
common, and not my case :~). I used to always specify the noatime
option, because I have no application relying on file access time.
Have you any such application installed?<br>
</p>
<p> I noticed your sysctl command, which, I guess, sets the
lifetime of data in the VFS buffers before they are actually
written to disk. It is also available in
/proc/sys/vm/dirtytime_expire_seconds and is set to 43200 in my
laptop. What is the goal of reducing it to 7200?</p>
<p> What does mean the line <span style="white-space: \
pre-wrap">"Percentage Used: 1%" in your diagnostic listing? Cause if only 1% of the \
disk is used, it should last longer than if 99% was used, but not many people can \
afford disks 100 time bigger than their storage need.</span></p> <p><span \
style="white-space: pre-wrap"> You also talk about the noise of a monster spinning \
disk used for backup, but the recommendation for a backup disk is to <b>not</b> let \
it powered all the time. I've read that a spinning disk used rarely is considered the \
most resilient backup storage, in contradiction with SSDs which loose data if they \
aren' t periodically powered.</span></p> <p><span style="white-space: \
pre-wrap"> Thanks.</span></p> <p><span style="white-space: pre-wrap">-- Didier
</span></p>
<pre class="moz-quote-pre" wrap="">
</pre>
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