[SATLUG] RAID5 Recovery - Reassembly looking good!!! :+)

Bruce Dubbs bruce.dubbs at gmail.com
Thu Aug 27 00:46:30 CDT 2009

Samuel Leon wrote:
> Forgot to mention, I am still not sure if there will be any 
> repercussions for upgrading libc6 the way that we did.  (we installed 
> the libc6 from jaunty into intrepid).  Maybe someone else on here might 
> know more about this.  Looking on the net all I see is that it "is not a 
> good idea".  Not sure if anything bad will happen though.  I would keep 
> an eye on it and make sure after everything is done that the server can 
> restart and boot up alright.

It shouldn't be a problem.  It is "just" a set of libraries.  Well, they *are* 
special libraries.  In any case, it is pretty generally backward compatible. 
When it's installed, all the applications that used the old version will 
continue to see it, but when the last application finished, it is deleted.  The 
old version is not visible or accessible by new processes.

If the whole thing didn't crash, then I'd say you are OK.  Just do something 
like 'ldd /bin/ls' to check that the new library is being recognized.

I have:

core2$ ldd /bin/ls
         linux-vdso.so.1 =>  (0x00007fff55bff000)
         librt.so.1 => /lib/librt.so.1 (0x00007fd33def5000)
         libc.so.6 => /lib/libc.so.6 (0x00007fd33dba2000)
         libpthread.so.0 => /lib/libpthread.so.0 (0x00007fd33d987000)
         /lib64/ld-linux-x86-64.so.2 (0x00007fd33e0fd000)

on one system and

lfs6$ ldd /bin/ls
         linux-gate.so.1 =>  (0xffffe000)
         librt.so.1 => /lib/librt.so.1 (0xb7ed6000)
         libc.so.6 => /lib/libc.so.6 (0xb7db5000)
         libpthread.so.0 => /lib/libpthread.so.0 (0xb7da2000)
         /lib/ld-linux.so.2 (0xb7ef8000)

on another.  The libc.so.6 looks the same but they are different.  To really see 
what you have, try:

lfs6$ /lib/libc.so.6 | head -n1
GNU C Library stable release version 2.3.6, by Roland McGrath et al.

core2$ /lib/libc.so.6 | head -n1
GNU C Library stable release version 2.10.1, by Roland McGrath et al.

and we see that they are quite different.  If I rebooted to my 32-bit version on 
the core2 system, then my ls binary from my old lfs6 system would work fine with 
the new libc version 2.10.1.

Going the other way - a new binary with an old library - is much more of a 
problem and may not run at all.

   -- Bruce

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