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Does anyone know what is that boot_archive file. It is located under /platform/sun4v/

/platform/sun4v>  du -sh * | sort -rn
342M   boot_archive ****
190M   failsafe
106K   lib
71K   bootlst
12M   kernel
1.0M   wanboot

It seemed too large to me. Any idea about it ?

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up vote 5 down vote accepted

342M isn't that big. My T-5140 servers, running Solaris 10 with Sun Cluster, have boot archives in the range of 355M to 375M.

The boot_archive file is like the linux ramdisk image. It contains a kernel image, all the kernel modules, and several configuration files. It's read during the boot process, prior to / being mounted. Once / is mounted, the ramdisk image is discarded, and the real files are read directly from disk.

If you're curious about the contents, the boot archive is a gzipped ISO 9660 filesystem.

cp /platform/$(uname -m)/boot_archive /tmp/boot_archive.gz
gunzip /tmp/boot_archive.gz
lofiadm -a /tmp/boot_archive
mount -F hsfs /dev/lofi/X /mnt  # <- change X to your lofi dev number
cd /mnt

and explore. you'll see exactly what's taking up space.

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thanks for reply. Well this a clustered system. What makes me think it is big is that, size of peer unit is almost 96 MB. Should they be same or such difference is normal ? – mibzer Mar 27 '12 at 15:02
interesting. on all the clusters I have, they are all the same size. consider running 'bootadm update-archive' on both servers, then if they're still vastly different sizes you can mount them and compare them. i can't find any documentation anywhere that mentions boot archive's in a cluster should be a consistent size. This said, our cluster nodes are all pretty evenly utilized. – Tim Kennedy Mar 27 '12 at 15:12
I mounted the boot_archive file and checked the content. Strange thing is content almost around 94 MB. Please check this question though -> unix.stackexchange.com/questions/35602/… – mibzer Apr 5 '12 at 21:37
i'm not sure what it is, but on all the servers I manage, the boot_archives are all in the 342-375MB range. perhaps this extra empty space is some sort of swap space that's built into the image, as the image size on all the servers I have always comes out slightly smaller than the 384MB required minimum RAM for Solaris. maybe it uses that space to be able to mount a ram disk with space for /proc and /tmp until such time as all the drivers are loaded and the real filesytems are mounted. – Tim Kennedy Apr 9 '12 at 19:16

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