Partition setup with SSD: Some questions.

Hantabaru · 2010-11-20 23:23:44

Hi

(Questions are at the end...)

I am getting a new Lenovo Thinkpad t410s this week from work and it has a 128 SSD, this amongst other things has led me to have to research a different install setup in relation to my previous method.

I have looked at the wiki and read the entry on SSD's and this suggest the following:

I should use the GPT method of partitioning which requires GRUB2..

My partition setup should look something like this:

Grub partition with no filesystem (partition type "EF02" in gdisk) approx 1MB
/boot ext2 ? MB
/ btrfs 25GB
/home btrfs remaining

My questions are sofar:

1. Are there any obvious faults with this setup?
2. How big should the /boot partition be?
3. Is ext2 ok for the /boot partition?

Last edited by Hantabaru (2010-11-20 23:53:06)

thestinger · 2010-11-21 00:27:28

ext2 is fine, but ext4 with the journal disabled (or even enabled) will be faster. Also, you might not want to use btrfs yet, it works, but you could lose all your data, and ext4 also supports the discard mount option for TRIM.

root@arch i ~ # du -s /boot
23M /boot

This is my boot partition with 2 kernels installed (the arch kernel plus a custom one), 50-100MB is more than enough (I'd go for 100MB, the kernel keeps getting bigger ).

EDIT: Also, 25GB for / is overkill, I would divide it into 8GB (at most) for /, and 4GB for a separate /var (before /home).

Last edited by thestinger (2010-11-21 00:28:47)

Hantabaru · 2010-11-21 00:58:27

Thanks.

Quick question...Why the separate /var?

thestinger · 2010-11-21 01:07:50

it stops logging or a broken program from wasting all the space on /, which can break everything, it's not at all necessary though

Hantabaru · 2010-11-21 06:31:08

Cool. I very much appreciate the help.

I will take your advice and set it up as you suggest.

Forgot to say I will also mount /tmp to ram using tmpfs.

BTW, I used such a large / because I have had the / grow to as much as 17.5GB before and I understood that it was good practice to not have a partition more than 75 % full, but maybe that was the /var section growing that made it so big?

Last edited by Hantabaru (2010-11-21 07:10:49)

graysky · 2010-11-21 10:12:39

Hantabaru - probably your /home no? Try ncdu to see or bigpkg to see which are your biggest packages.

-I keep my boot @ 200 MB to allow for 6 kernels (3 main/3 fallbacks) + memtest +grub candy.
-Put var in its own partition as stinger said and don't use btrfs just yet (ext4 is great and you can leave journaling enabled).

Hantabaru · 2010-11-21 11:29:21

/home was in the same partition but I had a separate /data partition for my files so I thought the size of /home wouldn't be all that big.

Will probably have /boot at 100MB seeing as i have just the one kernel + Fallback.

Will take the advice given about using ext4 instead of btrfs.

Thanks.

thestinger · 2010-11-21 17:51:09

the pacman cache will get bigger and bigger if you don't use pacman -Sc now and then, and log files can get huge too (but logrotate takes care of them eventually), so it might have been the /var

4GB is more than enough though for /var (and nothing will break that badly if it gets filled, which can be fixed with pacman -Sc)

Last edited by thestinger (2010-11-21 17:51:28)

milomouse · 2010-11-22 22:51:48

i'd shrink /boot even more if i were you. i have 6 kernel images (3 main/3 fallback, using lilo, have a few gpg keys on there as well) and it's only 46MB. probably be more than enough for you to have 65-75MB instead of 100MB since you wont be messing with too many kernel images, etc, unless you just want to play it safe or do some early chrooting stuff there or grub extras(?). personally, i don't think 2 kernel images (1 main/1 fallback) will ever get that big in the future but who knows. just my advice on the matter. also, my /var is using 609MB. as thestinger said, 4GB would be more than enough but definitely worth it to be separate (log files for troubleshooting if / partition messes up, etc, and pacman cache for reinstalls, etc, among other reasons).

Hantabaru · 2010-11-23 18:57:07

milomouse wrote:

i'd shrink /boot even more if i were you. i have 6 kernel images (3 main/3 fallback, using lilo, have a few gpg keys on there as well) and it's only 46MB. probably be more than enough for you to have 65-75MB instead of 100MB since you wont be messing with too many kernel images, etc, unless you just want to play it safe or do some early chrooting stuff there or grub extras(?). personally, i don't think 2 kernel images (1 main/1 fallback) will ever get that big in the future but who knows. just my advice on the matter. also, my /var is using 609MB. as thestinger said, 4GB would be more than enough but definitely worth it to be separate (log files for troubleshooting if / partition messes up, etc, and pacman cache for reinstalls, etc, among other reasons).

Ok...so I think it looks like I should have:

Grub partition with no filesystem (partition type "EF02" in gdisk) approx 1MB
/boot ext4 (no journalling) 75 MB
/ ext4 10 GB [Edit: I know this is a bit bigger than suggested but I more comfortable with the extra 2GB]
/var ext4 4 GB
/tmp in RAM with tmpfs
/home ext4 remaining

Just wondering do I really need to turn journalling off on the other three partitions?

Will it have that much effect on the life of the drive?

Edit: Just re-read the SSD entry in the wiki and it seems that turning off journalling probably will not make that much difference to the life of the drive.

Does that mean I should not bother turning off journalling for /boot then to maintain safety associated with journalling or is journalling not as important for /boot?

Last edited by Hantabaru (2010-11-23 20:12:23)

thestinger · 2010-11-23 23:37:37

It's not that important since writing to /boot is so rare (kernel upgrades/changes or generating new kernel images) and it won't affect performance at all (it only slows down writes and changes to metadata, not reading files).

It will waste some space though, so that's the only reason not to use it.

There aren't really any good arguments for having it enabled OR disabled, so just don't worry about it and leave it at the default (enabled).

Last edited by thestinger (2010-11-23 23:38:06)

Hantabaru · 2010-11-24 15:55:25

thestinger wrote:

It's not that important since writing to /boot is so rare (kernel upgrades/changes or generating new kernel images) and it won't affect performance at all (it only slows down writes and changes to metadata, not reading files).
It will waste some space though, so that's the only reason not to use it.
There aren't really any good arguments for having it enabled OR disabled, so just don't worry about it and leave it at the default (enabled).

Thanks.

This will be a work machine that I will maintain myself so I am having to balance the performance versus the reliability of the machine.

Arch Linux

#1 2010-11-20 23:23:44

Partition setup with SSD: Some questions.

#2 2010-11-21 00:27:28

Re: Partition setup with SSD: Some questions.

#3 2010-11-21 00:58:27

Re: Partition setup with SSD: Some questions.

#4 2010-11-21 01:07:50

Re: Partition setup with SSD: Some questions.

#5 2010-11-21 06:31:08

Re: Partition setup with SSD: Some questions.

#6 2010-11-21 10:12:39

Re: Partition setup with SSD: Some questions.

#7 2010-11-21 11:29:21

Re: Partition setup with SSD: Some questions.

#8 2010-11-21 17:51:09

Re: Partition setup with SSD: Some questions.

#9 2010-11-22 22:51:48

Re: Partition setup with SSD: Some questions.

#10 2010-11-23 18:57:07

Re: Partition setup with SSD: Some questions.

#11 2010-11-23 23:37:37

Re: Partition setup with SSD: Some questions.

#12 2010-11-24 15:55:25

Re: Partition setup with SSD: Some questions.

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