More experiences with Spherical Cow

[Chuck Forsberg WA7KGX N2469R]

On 09/08/2012 10:10 PM, John Reiser wrote:
> On 09/08/2012 03:49 PM, Chuck Forsberg WA7KGX N2469R wrote:
>> Lately I have been able to install new versions of Spherical Cow
>> using pxeboot with the liveos squashfs.  Installing over a
>> gigabit Ethernet is orders of magnitude faster than burning
>> a DVD-RW
> That's a big problem right there.  Install from DVD-RW is very slow
> for two reasons.  The '-' flavor does not have hardware-addressable
> sectors, so a seek-for-read must perform a "software" read at the
> destination to find the right 2KiB  sector.  The '+' flavor has
> hardware-addressable sectors which avoids this extra step.
>
> The second reason: both -/+RW are slow because the physical
> properties of the re-writable medium provide relatively low contrast.
> Neither the signal detector nor the writer can work quickly:
> "4X" is one practical knee.  The record-once (non-rewriteable) media
> provide much higher contrast, and "16X" is available inexpensively.
>
>> and watching it grinding away "forever" during
>> the install.
> I enjoy hyperbole once in a while, but let's make some actual measurements.
> As yet none of the pre-alpha Fedora 18 *.iso have worked for me,
> 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
>
> pxeboot + LiveOS squashfs + GigE cannot be even one order of magnitude
> faster than this, because creating the yum database takes longer than
> 2.4 minutes and depends only on the final result, not on any install method.
>
> Please measure your install, and tell us how long it takes.
>
The DVD+RW is much faster.  I didn't know there was much difference between
DVD-R and DVD+R.

-- 
Chuck Forsberg WA7KGX N2469R     caf at omen.com   www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
   Omen Technology Inc      "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430