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Auteur: Steve Litt
Datum:  
Aan: dng
Onderwerp: Re: [DNG] Devuan for Raspberry Pi fried SD CARD.
On Sun, 2 Dec 2018 11:10:20 -0800
Bruce Ferrell <bferrell@???> wrote:


> Yeah, this IS one of the issues around flash/SSD storage... They run
> fast and wear out faster.


The preceding sentence is true but it's not the whole truth. If one
uses SSD the way they would spinning rust, that being run it 80% to 90%
full, with lots of writes, and expects years of service, one will
likely be disappointed. But there are many situations in which SSD has
sufficient lifetime.

Let me start with my setup:

=========================================================
[root@mydesk mnt]# mount | grep sda
/dev/sda1 on / type ext4 (rw,noatime)
[root@mydesk mnt]# df -h /
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       220G   29G  181G  14% /
[root@mydesk mnt]# mount | grep "/dev/sd"
/dev/sda1 on / type ext4 (rw,noatime)
/dev/sdb1 on /boot type ext4 (rw,noatime)
/dev/sdb7 on /tmp type ext4 (rw,noatime)
/dev/sdb6 on /var type ext4 (rw,noatime)
/dev/sdb8 on /run type ext4 (rw,noatime)
/dev/sdc9 on /home type ext4 (rw,noatime)
/dev/sdc1 on /s type ext4 (rw,noatime)
/dev/sdc2 on /d type ext4 (rw,noatime)
/dev/sdc4 on /classic/a type ext4 (rw,noatime)
/dev/sdc5 on /classic/b type ext4 (rw,noatime)
/dev/sdc6 on /classic/c type ext4 (rw,noatime)
/dev/sdc7 on /home/slitt/mail/Maildir type ext4 (rw,noatime)
/dev/sdc8 on /scratch type ext4 (rw,noatime)
/dev/sdc3 on /inst type ext4 (rw,noatime)
[root@mydesk mnt]#
=========================================================


* Everything likely to have multitudes of writes under normal operating
conditions is mounted spinning rust.

* Only 1/5 of the SSD is used, so what few writes there are are
distributed across lots of space.

* I delete unneeded stuff and fstrim / every few days, so the SSD
doesn't fill up with erased stuff.

* I expect only 4 years life from any drive, spinning rust or SSD. At
least half of my disks have blown up within 4 years: That's life. My
SSD is currently 4 years old.

The OP's situation differs from mine in one major factor: He has no
spinning rust to offload writes to. So he'll use all the great
suggestions in the thread: noatime, put /tmp and logs in RAM
filesystems, fstrim early and often, and load it exclusively with files
it's meant to handle (I think the OP wanted an mp3 juke box).

Some people suggested using a USB thumb drive for temp and often
written files. This is a great idea because you can buy a 64GB thumb
drive for about $20.00 to $30.00 USD, and just throw it away when it
breaks. Keep the music on the SSD for speed and reliability, but if the
music player software happens to write to /tmp, that's on the thumb
drive that gets replaced every couple years.

An internal 1TB SSD can be had for under $150. External for less than
$200. If you buy 1TB and be sure to use only 100GB, follow all the tips
and fstrim every few days, this SSD should last for years. If we assume
that each song is 5MB, you can hold 20,000 songs in 100GB. If for some
reason you need to store more than 100GB, well, that's what spinning
rust is for: Add one.

So it's true, SSDs run fast and wear out faster, but the wear out
faster part is only if you use them the same way you use spinning rust.


SteveT

Steve Litt
December 2018 featured book: Rapid Learning for the 21st Century
http://www.troubleshooters.com/rl21