new gentoo install on ssd

queen · Veteran Joined: 19 Jul 2005 Posts: 1642

Hi Everyone

I bought a new ssd and would like to install gentoo. First time installation on ssd (samsung evo 850 250gb). I read the wiki and few posts in the forums, but they seem too old and outdated. Can anyone give some details about partitions and formating options, how make.conf file looks like, swap with which flags, erase block sizes, tmpfs, compilation where to write?

I thought of partition of boot as ext4, swap and root also ext4.
What other features I should consider?
Are there any changes I should apply to the wiki page about ssd?

I have 8gb ram. How much swap I should consider?

Thanks
Queen

eccerr0r · Posted: Thu Jul 06, 2017 2:39 am Post subject:

Recent versions of fdisk automatically take things into account - use 1MiB partition boundaries and you'll be fine.

You don't need to treat the SSD anything different than other HDDs, hence they are "outdated" because they don't need anything special.

I have swap == physical memory mainly so that I can hibernate to disk, though compression reduces the amount of swap needed. However it's all up to how you use your computer to decide how much swap you need. I'd say at least 2GB swap with 8GB RAM so you have enough warning before your processes get killed from out of memory, yet still have enough that your processes may still be able to complete before OOM kills something which may otherwise complete, saving you time and frustration.
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The Doctor · Moderator Joined: 27 Jul 2010 Posts: 2678

Consider that SSD storage is expensive so a large mechanical drive for data is a plus. Put the OS on the SSD and everything not access time sensitive on the mechanical drive. I would put swap there as well since you are unlikely to actually use it.

Other than that, /boot should probably be vfat if you are using UEFI. Also strongly consider /tmp and /var/tmp in ram. It is faster and there is no reason those should be persistent anyway.
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audiodef · Posted: Sun Jul 09, 2017 3:17 pm Post subject:

I used an SSD for a Gentoo install not long ago. No specials steps need be taken. After install, I symlinked my home dir to a large HDD so that all software gets installed on the SSD and all my files are stored on the HDD.
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queen · Veteran Joined: 19 Jul 2005 Posts: 1642

Hi

Sorry for the delay of the reply. It was busy week. Thanks for the help. I would like to know how much space to leave in ram for /tmp and /var/tmp?
I am thinking of a line like this in /etc/fstab

charles17 · Advocate Joined: 02 Mar 2008 Posts: 3664

NeddySeagoon · Posted: Thu Jul 13, 2017 9:06 am Post subject:

queen,

The default size for tmpfs is half your RAM. Its not reserved, though. tmpfs is a disk cache with no permanent storage behind it.
firefox and libreoffice need 4G each so as long as you don't build them both at the same time, 4G for /var/tmp/portage will be fine.
If you have >8G ram, there is no need to set a tmpfs size. The default half RAM will work and RAM will not be wasted.

The MiB partition boundaries ensures partition alignments. MiB being a binary Megabyte (1024x1024) not a HDD (1000x1000) Megabyte.

SSDs have a write block size of 4096B and an erase block of something more that that. It varies from SSD to SDD and its usually not published.
When a block in an SSD is erased, its the erase block size that's used. This means that any data still needed within the erase block must be moved
causing extra writes. This is called 'write amplification' its a feature of SSDs that contributes to SSD wear out.
If you read up on 'write amplification' be sure to read current material.
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eccerr0r · Posted: Thu Jul 13, 2017 2:09 pm Post subject:

I've been having trouble building firefox in 4GB of tmpfs on my 8G machine - it checks for 4GB and usually with some stuff on tmpfs, it's less than 4GB free so the check fails. Recently I've need to set it to 5GB manually to get around this issue.
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?