Using /home only for application-specific settings?

[user42]

Being still a newbie I recently
Applications (Firefox, Kate, ...) take longer to start than in Win7, why? - #33 by hui learned that a slowing down of application (and system) start probably is because I placed /home
at the HDD, instead of the SSD.
When starting system/ applications it makes heavy use of settings, caches etc.
and as HDD is much slower…

However my personal data is of large extend (Several TB); no go for SSD.
So I would leave them at the HDD in some folders.

Still I wonder:
openSUSE autocreates subdirs in /home like documents, pictures, movies, downloads etc.
That’s why I (and probably not only me) thought it would be best to do that kind of data there.

My question:
Will there be any problems when I have /home in it’s own partition on the SSD,
but only for the application settings, caches etc.?
Won’t for example applications (or maybe the system itself) expect users’ data
beyond /home? Say an image app uses /home/pictures per default.
Maybe IDEs expects projects beyond /home/devel…?
And maybe several other services etc.
So I probably would have to change (manually) the default subdir (if possible)?

Maybe I have to use hard-links etc. to associate the other folders etc.?

If it will be possible that way, the next question would be which filesystem
for /home (/ is btrfs, old /home is ext4), and what size.

[myswtest]

Maybe you should mention approximate TB usage.

Some of the largest SSD are 100 TB, the largest is 122 TB.

The largest available HDD, in my research is 36 TB.

So SSD is a way better option.

Personally, I can’t even imagine that much usage, unless I’m working at some video processing organization.

EDIT: might be better in the Open Chat

[malcolmlewis]

@user42 On my setup here I have a disk (well it’s hardware RAID1) that is just use for data and then soflinks in /home/username of directories, for example /home/username/Documents is a softlink to /data/Documents. So the stuff I want is separate and easier to backup with rsync without having to add lots of excludes… Now I’m not using btrfs on this system i have ext4 at present…

lsblk

NAME        MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINTS
sda           8:0    0 476.9G  0 disk  
├─md126       9:126  0 453.1G  0 raid1 /data
└─md127       9:127  0     0B  0       
sdb           8:16   0 476.9G  0 disk  
├─md126       9:126  0 453.1G  0 raid1 /data
└─md127       9:127  0     0B  0       
sdc           8:32   0 111.8G  0 disk  
└─sdc1        8:33   0 111.8G  0 part  /build
nvme0n1     259:0    0 953.9G  0 disk  
├─nvme0n1p1 259:1    0     4G  0 part  /boot/efi
└─nvme0n1p2 259:2    0 949.9G  0 part  /

[hui]

With Plasma you can really easy define that these user directories (documents, music, video,…) all point to a completely different drive or directory. I point them all to one single directory which is mounted on a seperate drive.

[user42]

Hmm… from your answers I get that these subdirs are necessary and “should be handled with care” (i.e. not only deleted and just use other ones at the HDD).

OK, but I just had an idea that might make it unnecessary to move /home from HDD to SSD:
Instead of moving whole /home to a new partition at the SSD just to have the application settings/ caches at the SSD, why don’t do it “the other way round”?
What I mean:
Split-off some of / at the SSD and make it the partition for the application-specific subdirs at /home. Then do a softlink from the former subdirs for application-specific data at the HDD to the new partition at the HDD.
So all the other folders could remain as they are at the HDD,
and the time-critical application-specific settings are at SSD.
Still accessed by a link respectively.
Moreover I wouldn’t have to move /home (which seems to be a non-newbie task…)