so I'll measure Fedora 17 Release (x86_64) on 3GHz CPU, 8GB RAM,
SATA II:
Duration Activity
======== ========
12m26s write DVD+RW (3.8GB; 4X)
5m00s write DVD+R (3.8GB; 16X)
-=-=-=-
3m48s Boot DVD+R, go until "Starting installation process"
2m32s Starting installation process
9m32s install 1207 packages (default Gnome Desktop; 4.1GB)
2m56s create yum package database using links in filesystem
------
18m48s installation
5m00s media preparation
======
23m48s .iso-to-installed
Doing the same thing on the same hardware, except with the installation source
on a USB2.0 flash memory device with vfat filesystem:
38m58s livecd-iso-to-disk
-=-=-=-
3m22s Boot DVD+R, go until "Starting installation process"
0m12s Starting installation process
8m10s install 1207 packages (default Gnome Desktop; 4.1GB)
3m09s create yum package database using links in filesystem
------
14m53s installation
38m58s media preparation
======
53m51s .iso-to-installed
Note the factor of 12.7 speedup for "Starting install process": 12s instead of
2m32s.
This shows how much faster seeking is on the flash device instead of on the DVD+R.
The installation is almost 4 minutes faster (21%) using the flash device,
but media preparation takes about 34 minutes longer (a factor of 7.6)
livecd-iso-to-disk spends nearly all its time transferring the Packages
directory using rsync. I wonder how much might be saved if vfat supported
the fallocate() system call (and rsync used it.)
The flash memory device might be considered slow:
dd if=/dev/flash bs=32k count=10000 of=/dev/null
transfers 328MB in 19.3 seconds, which is an average of 17.0 MB/s.
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