Pacman Speed Issue - The Reason ???

MetalheadGautham · 2009-01-29 03:31:56

I initially had a severe speed issue with pacman package manager. At first, when I had installed archlinux, pacman worked smooth as butter. But then, in the past month or two, it became increasingly slow. A simple sudo pacman -Syu took over 2 minutes to execute and go to the [Y/n] menu.

I asked in this forums the question several times but got no good reply. Many said its an issue faced when using EXT2 file system. I was adviced to use EXT3 which I already use. This only made me more confused.

A few days back, I noticed that I had alarmingly less free disc space on my / partition. I checked /var/cache/pacman/ and noticed that pacman cache occupied almost 3.7GB, in my 10GB / partition. So I decided to do a sudo pacman -Sc -KeepCurrent and freed up 2GB of space.

My harddisc configuration is: ~10GB for /, ~10GB for home and ~496MB for swap.

Since then, pacman speeds have returned to normal. A search for a non-existant package no longer takes over a minute to execute - its done in less than a handful of seconds.

So my question is, WHY is pacman's speed linked to free space available in the root partition ?

I know for one that pacman configuration is stored in a thousand tiny files.
I also know that access times are great in EXT3 because its a Journalising File System.
Would low disc space cause journal to be not written or something like that ?

Allan · 2009-01-29 03:40:50

My guess is that with low disk space, the database files became fragmented over the hard-drive.

MetalheadGautham · 2009-01-29 03:55:05

Then how is the condition different when the disc space comes back ?
Does EXT3 have some automatic defragmentation algo ? I think not.
Isn't journalising supposed to PREVENT the ill effects of fragmentation ?
And is 500mb free space really THAT low for database files ????

tdy · 2009-01-29 04:13:21

MetalheadGautham wrote:

Isn't journalising supposed to PREVENT the ill effects of fragmentation ?

That's just an idea propagated by fanboys. The rate/severity of fragmentation will vary, but any filesystem will become fragmented over time. Regardless of what you use, optimal file allocation becomes increasingly impossible as you approach 0 space.

MetalheadGautham · 2009-01-29 04:23:02

Then is there a defragmentation software for an ext3 file system ?

Allan · 2009-01-29 04:24:03

I guess you updated you pacman database (pacman -Sy) which would have rewritten the pacman database to a nice contiguous block. Although, it would have done nothing to your local database (for your installed packages).

MetalheadGautham · 2009-01-29 04:44:07

Thats what I think too.

So is there any way to defragment linux ? OR is it easier to backup configuration files and local repository and reinstall archlinux and restore config files and copy back local cache to pacman cache ?

Mr.Elendig · 2009-01-30 15:32:55

`pacman-optimize` will rewrite your local db to a continuis block (if it's able too, as noted, there has to bee a large enough are free)

For the question about defrag, there exist some tools to defrag ext3 but they are 3.rd party. xfs has a official defrag tool, and ext4 is getting one 'soon' (maby as soon as with kernel .29)

Wintervenom · 2009-01-30 20:43:34

MetalheadGautham wrote:

Then is there a defragmentation software for an ext3 file system ?

pacman -S shake

Zibi1981 · 2009-01-31 10:59:29

There's also FS-independent fiDefrag.

Off-topic (slightly): when I was starting my adventure with Linux somewhat two years ago everyone claimed that the filesystems it utilizes didn't need a defragmenting tool. I was very suspicious about that, although I'm not a computer geek. Seems I was right. Maybe JFS or Ext3 are more resistant to fragmentation than NTFS, but they eventually require defragmentation.

MetalheadGautham · 2009-02-01 11:13:50

I personally feel it would be safer to defragment a partition when its not mounted.
So would it be better to use "shake" from a live Boot ?
And does archlinux have a flash drive optimised boot mode ?
Or is there any defrag software on Knoppix 6.0 Live CD ?

Allan · 2009-02-01 11:23:02

It does not make much difference with these packages. They work by moving each file to a hopefully more contiguous position.

Arch Linux

#1 2009-01-29 03:31:56

Pacman Speed Issue - The Reason ???

#2 2009-01-29 03:40:50

Re: Pacman Speed Issue - The Reason ???

#3 2009-01-29 03:55:05

Re: Pacman Speed Issue - The Reason ???

#4 2009-01-29 04:13:21

Re: Pacman Speed Issue - The Reason ???

#5 2009-01-29 04:23:02

Re: Pacman Speed Issue - The Reason ???

#6 2009-01-29 04:24:03

Re: Pacman Speed Issue - The Reason ???

#7 2009-01-29 04:44:07

Re: Pacman Speed Issue - The Reason ???

#8 2009-01-30 15:32:55

Re: Pacman Speed Issue - The Reason ???

#9 2009-01-30 20:43:34

Re: Pacman Speed Issue - The Reason ???

#10 2009-01-31 10:59:29

Re: Pacman Speed Issue - The Reason ???

#11 2009-02-01 11:13:50

Re: Pacman Speed Issue - The Reason ???

#12 2009-02-01 11:23:02

Re: Pacman Speed Issue - The Reason ???

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