Re: Reasonably simple setup for 1TB HDD and 250GB M.2 NVMe SSD

["Alexander V. Makartsev" <avbetev@gmail.com>]

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 complex and probably outdated (last modified 2013-10-17).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.

⢀⣴⠾⠻⢶⣦⠀ 
⣾⠁⢠⠒⠀⣿⡁ Debian - The universal operating system
⢿⡄⠘⠷⠚⠋⠀ https://www.debian.org
⠈⠳⣄⠀⠀⠀⠀