Arch Linux

Spec-Chum

Member

Registered: 2013-05-28

Posts: 11

Best use of 2 SSDs?

Hi all, I impulse bought a new SSD.  As you do every day.  And now I’m just wondering of the best way to utilise it.  I’ve already got Arch on another SSD so it’s not exactly slow already

Apart from the obvious, moving swap and /home to this new drive, what else do you think would benefit from being moved?

I mainly use Arch for browsing, IRC and programming, so I could obviously have a /scratch partition for GCC and the like, but it seems a bit of a waste of 80Gb haha

Relevant system specs:
Quad Core i7
4Gb RAM
2 x 80Gb SSDs
3Tb worth of mechanical drives for photos, music etc

Edit: oh and Arch with OpenBox!

Any ideas welcome.

Spec

Last edited by Spec-Chum (2013-07-18 13:46:18)

jakobcreutzfeldt

Member

Registered: 2011-05-12

Posts: 1,042

Re: Best use of 2 SSDs?

You can send one to me, if you'd like.

Maybe mirror your original disk?

Last edited by jakobcreutzfeldt (2013-07-18 12:41:53)

arokh

Member

Registered: 2013-05-30

Posts: 35

Re: Best use of 2 SSDs?

You won't notice any difference putting swap or home on a different disk when both are ssd. You could stripe them together with raid 0 (either using md or btrfs) that should provide a speed benefit at the cost of redundancy. Backups will be important

Spec-Chum

Member

Registered: 2013-05-28

Posts: 11

Re: Best use of 2 SSDs?

Thanks both

I've had a think again and I want to avoid raid arrays as I think I'm going to split 1 of them and have 2 distros to dual boot.  Using the other half (well, maybe 20Gb) for "temp" files like a Download folder, GCC /tmp, anything that could be shared between the 2 really.

Not exactly sure what I was expecting to gain

WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: Best use of 2 SSDs?

I don't quite understand why having a RAID array would prevent you from doing a dual bot setup.  I mean, if you are dual booting all Linux, then you could very easily just mdadm the two together and then treat it as one big-ass drive.  You could use it is a big-ass drive as well.  So that means you could put an LVM on top of it and separate it out between your distro choices.  Or you could simply use regular partitions on top of the mdadm array.  Of course this assumes that the disks are of similar size.  But if they are not, you could also just mdadm two same sized partitions together.  In fact, you could use half of each SSD, mdadm them together, then still use the other halves to do with as you please.

I am also not sure what the "temp" is really for.  I mean, unless you are concerned about partition size limiting the ability to compile, then it shouldn't really matter where you put it.  For example, if you wanted to have a small rootfs where you decided to compile gnome, that might not work.  But then you shouldn't be compiling as root anyway, so wherever you do that you should have permissions to run as your user.  Typically that is in your /home folder.

I have a Samsung 840 250GB, as Samsung 830 128GB, and a Mushkin Atlas 128GB mSATA in my Thinkpad.  I have the two Samsungs in a single btrfs pool.  The 840 also hold my ESP (/boot), so it's contribution to the btrfs pool is ~231GB while the 830 spans the whole disk (with btrfs you don't have to use a partition, and though it says it is using the whole disk, it actually leaves a small section in the start of the disk free so you can still have a bios bootloader).  So my data is in "single" mode, meaning that is it just, well... single.  But I have the metadata and system data in raid1.  I wanted to do raid0 or raid1, but the size difference would be too much for btrfs to compensate for.  I guess I could add the Mushkin, but the mSATA port is only SATAII, so teh speed difference is too great.

Anyway, I would recommend btrfs.  It is really cool and feature packed.  Also by using subvolumes, you don't have to really partition your drive all up into chunks.  Subvolumes will also allow you to have multiple distributions in the same btrfs pool, since it allows to to arbitrarily decide what subvol will act as the root.  But if you use multiple distributions in the same pool, you have to make sure you are using very similar kernel and btrfs-progs versions.  But if you are using btrfs, you should be using at least the latest stable kernel anyway, and btrfs-progs' git version is easily built.

Spec-Chum

Member

Registered: 2013-05-28

Posts: 11

Re: Best use of 2 SSDs?

Interesting, I must admit I've never used btrfs.

Looks like it's wiki time

Last edited by Spec-Chum (2013-07-18 15:19:20)

WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: Best use of 2 SSDs?

Check out the btrfs wiki. Our wiki covers the basics, but there is quite a bit more that the filesystem can do.  On the main page I linked to there, there is a list of articles about half way down the page.  The two by Margaret Bierman and Lenz Grimmer are a couple of nice short ones that will actually give you a relatively good sense of some of the really main features that it has to offer.