Gentoo Archives: gentoo-desktop

From: Adam James <ad@×××××××××××××.uk>
To: gentoo-desktop@l.g.o
Subject: Re: [gentoo-desktop] disk partitioning
Date: Tue, 06 Feb 2007 20:05:30
In Reply to: Re: [gentoo-desktop] disk partitioning by "Boyd Stephen Smith Jr."
On Tue, 6 Feb 2007 12:20:26 -0600
"Boyd Stephen Smith Jr." <bss03@××××××××××.net> wrote:

> On Tuesday 06 February 2007, Mikko Husari <husku@×××××.net> wrote > about 'Re: [gentoo-desktop] disk partitioning': > > hmm, im really new to all that lvm stuff but i think i have a > > general idea about it, does it reduce performance at all? > > Yes, but it's a completely insignificant amount compared to the > additional flexibility it gives. Commercial UNIXes (HP-UX and AIX) > have been defaulting to LVM for years, if not decades.
LVM works by dividing the disk into "physical extents" (the size of which are configurable on volume group creation), thus it is not guaranteed that all the data contained within a logical volume will be in one contiguous area on the disk. If this is the case, then the disk head will spend more time seeking, increasing the latency of a read/write operation. You can mitigate this on a per partition basis by specifiying '--contiguous y' when creating a logical volume with lvcreate. If you do decide to use a separate partition for portage then it is sensible to specify a block size of 2048 bytes when you format it (this is the -b option, at least for mkfs.ext* and mkreiserfs). As most files in the tree are ~2KiB, there is a significant amount of wastage with the default blocksize of 4096 bytes. It reduced the filesystem usage of the tree on my system from ~500MiB to ~250MiB, if I recall correctly. --atj -- gentoo-desktop@g.o mailing list