Date: Sun, 09 Dec 2001 12:50:49 -0800 From: Bakul Shah <bakul@bitblocks.com> To: freebsd-arch@FreeBSD.ORG Subject: Real world Root Resizing (was Re: Proposed auto-sizing patch ... Message-ID: <200112092050.PAA26830@glatton.cnchost.com>
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Changing sysinstall helps new installations but doesn't help
existing systems with a "tiny" root fs -- something I had to
fix recently. I was surprised to see how easy it was!
Here is the procedure I used, in case anyone else needs to do
the same. Assume ad0s1a is the root filesystem and ad0s1b is
the swap partition and its size is atleast new root fs size +
old root fs size. Do this as single user on a freshly booted
system.
1. disklabel ad0s1 > label # save a copy of the disklabel
2. disklabel -e ad0s1
if the new root size is N, change the b partition to start at offset N.
make its size the same as partition a and make its type 4.2BSD type.
3. dd </dev/ad0s1a >/dev/ad0s1b bs=1m
4. fsck /dev/ad0s1b
5. echo 'boot_askname="YES"' >> /boot/loader.conf
6. shutdown -r now
7. boot in single user mode and when asked, choose the b partition as root.
8. disklabel -e ad0s1
change 'a' partition size to N.
9. growfs -s N /dev/ad0s1a
10. fsck /dev/ad0s1a # just to convince yourself everything is okay
11. shutdown -r now
12. boot in single user mode and when aske, choose the a partition as root.
13. disklabel -e ad0s1
restore the swap partition (to its new reduced size)
14. remove the change to /boot/loader.conf made in step 5.
15. reboot
If there is an easier way, I'd like to hear about it. In
particular if / can be switched at runtime, all of this can
be done in one program without so many reboots. One can even
write a program to shuffle filesystems around to grow any fs
so long as there is some space somewhere!
Disclaimer: use at your own risk. make backups and keep a
cleenex handy in case you screw up. make notes while doing
this to aid in debugging in case things go wrong.
growfs should take an optional argument -A (for Auto :-) to
grow a fs to fill up the partition. growfs needs to be
renamed grow_ufs in case in future growfs is extended to grow
other fs types. Ditto for newfs, dumpfs, tunafish and so on.
-- bakul
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