Changes between Version 13 and Version 14 of UpgradeNotes

Timestamp:

Aug 16, 2012 10:18:51 AM (12 years ago)

Author:

Ted Faber

Comment:

--

UpgradeNotes

@@ -58 +58 @@
 The sources are in {{{~mikeryan/dev/benito/vde}}} but the changes were not completely clear.
 
+= Compressing The Image =
+
+After getting everything installed on the image, it gets to be sizeable.  The qcow2 image was 3+ GB.  To reduce this, convert the image to a raw disk image
+
+{{{
+$ qemu-img convert -p -O raw pangolin.img pangolin.raw.img
+}}}
+
+Now we need to run {{{zerofree}}} to clear out the dirty sectors.  (zerofree is in the repo)
+
+I fooled around quite a bit with trying to boot a qemu instance from the qcow2 image and mount the raw image for zerofreeing.  This failed in many ways.  Attaching both disks always mounts the raw image and corrupts the qcow2.  You can make teh qcow2 image a disk and boot from it, with the raw image on a USB disk, but the zerofree is too slow.
+
+Ultimately the easy way to do this was to mount the raw image through the loopback, using the mechanism [http://askubuntu.com/questions/69363/mount-disk-device-image here].  Basically:
+
+{{{
+$ fdisk -lu pangolin.raw.img 
+
+Disk pangolin.raw.img: 10.7 GB, 10737418240 bytes
+255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors
+Units = sectors of 1 * 512 = 512 bytes
+Sector size (logical/physical): 512 bytes / 512 bytes
+I/O size (minimum/optimal): 512 bytes / 512 bytes
+Disk identifier: 0x0000b82d
+
+           Device Boot      Start         End      Blocks   Id  System
+pangolin.raw.img1   *        2048    18874367     9436160   83  Linux
+pangolin.raw.img2        18876414    20969471     1046529    5  Extended
+pangolin.raw.img5        18876416    20969471     1046528   82  Linux swap / Solaris
+$ dc
+512 2048 * p
+1048576
+# (sector size * start of partition)
+$ sudo losetup -o 1048576 /dev/loop0 pangolin.raw.img 
+$ sudo mount /dev/loop0 /mnt
+$ sudo zerofree -v /dev/loop0 
+247417/1655938/2359040
+$ sudo losetup -d /dev/loop0 
+# Don't forget -c for compression
+$ qemu-img convert -p -c -O qcow2 pangolin.raw.img pangolin-dev.img
+}}}
+
+The resulting image is roughly 1.1 GB.  A considerable savings.
 
 = Making DEBs for ViewOS =