[gPXE] Setting delay time to boot, so client waits for SAN server

[Summary for the Archive]

Op 20100328 om 01:57 schreef Fatih Tolga Ata:
> Hi,
> The OSes in my san servers boot slower than the remote machines which 
> boot from iSCSI targets. So, the remote machines can't boot because 
> iSCSI targets are still booting at this time. So if I want to restart 
> san servers, I have to go to the server room to restart the all remote 
> machines. So, is there any command line option to delay the booting? 
> I've looked at this page http://etherboot.org/wiki/commandline . But I 
> didn't find any info about delaying.
> 
> Regards.
> _______________________________________________

Op 20100328 om 03:42 schreef Miller, Shao:
> 
> Given that gPXE has a strong focus on small code size for ROM build
> targets, could 'waitfor' or other similar use cases be better
> implemented in a more generic fashion?
> 
> If the check can be accomplished by repeated download attempts in a
> loop, the scripting discussion in the gPXE developers' mailing-list
> could potentially come to fruition and accomplish this same behaviour in
> a more programmatically generic way, with 'if' and loops, for example.
> 
> As it stands, there are patches not yet committed to the gPXE official
> code-base which can accomplish the behaviour of the suggested 'waitfor'
> command, if the assumption is that a download trial is roughly the same
> as testing for <port>.
> 
> #!gpxe
> clear script_errors
> dhcp net0
> : test_download
> chain http://ip:8080/some_boot_file
> sleep 10
> goto test_download
> 
> In the above, 'chain' should not return, but if it does, we wait ten
> seconds and retry.  The above does not work in current gPXE, but does
> work with some of the patches under discussion.
> 
> - Shao Miller
> _______________________________________________


Op 20100328 om 11:55 schreef Piotr Jaroszy??ski:
> On 28 March 2010 11:42, Jonathan Andrews <jon at jonshouse.co.uk> wrote:
> > In that case could not waitfor simply be a macro within gpxe as all the
> > underlying functions would be in the codebase ? :-D
> 
> I think the idea is to just keep trying what you want to accomplish
> instead of doing some additional check to see whether the server is up
> at all.
> 
> > I prefer readable simple functions, the "chain" in the above code does
> > not seem obvious or friendly, also I cant even see how that loop escapes
> > - to me it reads as stuck as "goto" is not conditional?
> 
> Chain is like exec(), it doesn't return if successful.
> 
> -- 
> Best Regards
> Piotr Jaroszy??ski
> _______________________________________________