On 08.12.2021 19:27, Jorge P. de Morais Neto wrote:
Hi everyone! I have a Dell Inspiron 5570 laptop with 1TB HDD and 16 GiB
RAM (it supports 32 GiB). I am about to buy an M.2 NVMe 250GB SSD---a
Western Digital WD Blue SN550. I would like to set the system for
reliability, SSD durability¹ and performance.
I have looked at [Multi HDD/SSD Partitioning Scheme][] but it is too
complex and probably outdated (last modified 2013-10-17). I would like
something simpler. For backups, I would continue my weekly manual
backups to my 1.5 TB external HDD with duplicity.
On the SSD I intend to leave 35 GB unpartitioned for extra over
provisioning. It would have just one 215 GB partition.
On the HDD I would put a 34 GB swap partition at the beginning, then a
215 GB partition for RAID1 with the SSD, then a 751 GB partition. I
intend to put Debian system *and* /home on the 215 GB RAID1, but I would
set all the XDG user dirs² on the 751 GB HDD partition. I would have
tmpfs on /tmp---I have read that long thread where someone alleged that
moving /tmp to tmpfs makes it useless but I disagree.
Would all this be reasonable? Do you recommend any change? Any tip? I
run Debian stable with only official repositories, including
bullseye-backports. I also manually installed GNU Guix package manager
and my main Guix profile has 163 packages.
I'd advise against doing extra over-provisioning and making /swap on
slow HDD.
IMO it is a thing of the past, especially on a home\personal computer.
Modern NAND technology and provisioning algorithms made SSDs quite
resilient.
It is more likely that a controller IC will fail than a NAND ICs will
wear off themselves during mild daily usage.
I have a few dozen of SSD devices to back up my personal experience and
have access to information about two of them right now:
First model is "SKC400S37256G" made by Kingston. It is a 256GB SSD based
on 2D MLC-2bit NAND and rated 300TBW.
It is working inside a home PC as a system drive with swap and /home on
it. Manual TRIM once in 1-3 months. PC always shuts down (no hibernation).
According to SMART, it is working for 28132 hours¹ (3,2y) and has 98%
life left².
Second model is "SHFS37A120G" made by Kingston. It is a 120GB SSD based
on 2D MLC-2bit NAND and rated 354TBW.
It is working 24/7 inside a SOHO server as a system drive with swap on
it. /home is on another disk.
According to SMART, it is working for 48810 hours (5,5y) and has 94%
life left.
So, if you plan to use NVMe SSD as a system drive, I suggest you also
keep /swap partition and /home on it for a maximum system and apps
performance, and monitor it with smartmontools.
If you still want to save on its life you can always make symlinks for
write-intensive, but not important, directories, like Downloads, to the HDD.
Also, I suggest you to make backups of /home on daily schedule to HDD,
because data recovery from a failed SSD is not only very expensive, but
often also next to impossible.
Bottom line, there is a high probability that your SSD will work fine
for many years and if/when it will die for whatever reason, just replace
it and recover data (or a whole system) from backups.
¹ Attribute #9 - Power_ On_Hours.
² Attribute #231 - SSD_Life_Left.
--
With kindest regards, Alexander.
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