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#1 2011-07-05 18:33:01

cbo
Member
Registered: 2011-07-05
Posts: 7

Two possible ways to speed up Arch on an SSD?

First of all, apologies if a similar post has been made but it's hard to properly summarise this so a search didn't return anything.

I have an SSD/HDD setup on my computer and found the speed increase to be a little disappointing in some aspects. I realised that this is probably because of /usr being mounted on a HDD partiton. I had to do this because the SSD simply isn't big enough to store all my installed programs.

For reference, here is my mounting layout:

/: SSD
/boot: SSD
/usr: HDD
/home: HDD

Things like my DE (KDE) are fast in use but slow to load, presumably because it has to be loaded from the /usr on the HDD. I've had two ideas on possible ways to speed things up:

1: Use symlinks in place of the actual files.
Basically, this would involve making a new folder, say /usr-ssd which would be on the SSD and moving KDE and other systemy things into this folder. Symlinks would then be used in /usr where these files used to reside. I'm not sure whether this would work or not but I see no reason why it shouldn't. The thing is, one of the main advantages of an SSD is the hugely reduced access time. The fact that the HDD still has to load these symlinks before loading the actual files would presumably incur a performance loss. I'm not sure how much this method would help, it could even make things worse because two files have to be accessed instead of one.

2: Have the two /usr folders like before (one HDD and one SSD) and install certain things directly to /usr-ssd.
This would be the better solution because files would be accesses straight from the SSD. Is it possible for Arch installer and Pacman to install certain things to /usr-ssd?

There may be a really simple solution to this, so sorry if I've made a post for something really basic. I want to eek out every bit of performance the SSD has to offer though smile

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#2 2011-07-07 14:28:45

jeslinmx
Member
Registered: 2010-11-20
Posts: 120

Re: Two possible ways to speed up Arch on an SSD?

https://wiki.archlinux.org/index.php/SSD
Uhm, I'm pretty certain the first idea would work fine. Much of the KDE startup time is probably from loading the programs, and the symlink access is negligible.
I'm not certain about the pacman option though. You will likely be able to find such a functionality, so try going through man pacman.


Lenovo Y450 + Arch x86_64 dual boot with Windows 7 + Openbox standalone + Arch default kernel + Nouveau + yours truly = A lot of *****in' in the Arch Forums.

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#3 2011-07-07 14:56:24

measure
Member
Registered: 2009-07-17
Posts: 62

Re: Two possible ways to speed up Arch on an SSD?

Out of curiosity, how large is your SSD?  Furthermore, how large is your /usr directory?

Another possible solution would be to use a union mount (aufs, unionfs, etc.), as this would take care of itself a bit more seamlessly.


Thanks,
Ryan

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#4 2011-07-07 15:49:51

clearloon
Member
Registered: 2009-01-07
Posts: 79

Re: Two possible ways to speed up Arch on an SSD?

Hi -

I have a similar setup and I found that the slow speeds were mostly due to having ~/.kde on the HDD. Didn't seem to matter for /usr.

What worked for me is to put ~/ on the SSD so that all the config files (eg within ~/.kde & ~/.kde4) are on the SSD, but make all the subdirectories where I keep things (eg Documents, Desktop, Videos, Pictures etc...) symlinks to directories on the HDD.

Really made a difference for me but YMMV!

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#5 2011-07-09 07:53:32

Janusz11
Member
Registered: 2007-05-16
Posts: 80

Re: Two possible ways to speed up Arch on an SSD?

clearloon wrote:

What worked for me is to put ~/ on the SSD so that all the config files (eg within ~/.kde & ~/.kde4) are on the SSD, but make all the subdirectories where I keep things (eg Documents, Desktop, Videos, Pictures etc...) symlinks to directories on the HDD.

That's pretty much how I've set up my system as well. I have a 60GB OCZ Agility III and have parted it into three partitions for swap (1GB), root (20GB) and home (rest). Temp is mounted into tmpfs. Only for /var I have created a separate partition (20GB) on my HDD.

Home is used for configuration files only, really. Everything for my daily usage such as my music files, downloads and so on is all located on my HDD and I've created soft links from my /home partition to their respective location.

Works like a charm.

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#6 2011-07-22 21:51:42

cbo
Member
Registered: 2011-07-05
Posts: 7

Re: Two possible ways to speed up Arch on an SSD?

Sorry for the delay in replying. I've reinstalled from scratch with /usr on the SSD and it's much, much faster. I don't have an exact time but it was definitely faster and backgrounding the daemons has made it faster still.

It's probably mainly because /usr is on the SSD, however I also chose to have all the partitions barring /home running on XFS compared to the ext4 I had before. I'm not sure how much difference this makes, though XFS is supposed to be very good for loading large files (would the binaries executed at startup count as large?).

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#7 2011-07-22 21:54:43

litemotiv
Forum Fellow
Registered: 2008-08-01
Posts: 5,026

Re: Two possible ways to speed up Arch on an SSD?

cbo wrote:

It's probably mainly because /usr is on the SSD, however I also chose to have all the partitions barring /home running on XFS compared to the ext4 I had before. I'm not sure how much difference this makes, though XFS is supposed to be very good for loading large files (would the binaries executed at startup count as large?).

SSD 100%, XFS 0%

(roughly)


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#8 2011-07-23 10:57:00

cbo
Member
Registered: 2011-07-05
Posts: 7

Re: Two possible ways to speed up Arch on an SSD?

Hmm I'm not sure if I can trust those figures if they're only rough... tongue

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#9 2011-07-23 11:00:39

litemotiv
Forum Fellow
Registered: 2008-08-01
Posts: 5,026

Re: Two possible ways to speed up Arch on an SSD?

cbo wrote:

Hmm I'm not sure if I can trust those figures if they're only rough... tongue

Hehe, well 'large' files in this context really means 'large' files, say 5-10MB or larger. Anything in your system root will be much smaller than that, and ext4 should generally be faster in that regard than XFS. So from there you can conclude that any speed improvements you notice are almost solely caused by using the SSD, rather than using a different filesystem.


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