i'm wondering if i can upgrade F5 LTM 1600 from v9.4.7 to v10.2.1 directly? but not from v9.4.7 to v10.1.0 then v10.1.0 to v10.2.1?yes, you can.
sol13845: Overview of the supported BIG-IP upgrade paths and upgrade planning reference
http://support.f5.com/kb/en-us/solutions/public/13000/800/sol13845.html
another question,i have to install hotfix and 10.2.1 patches both in inactive patition?yes
If i install the patch with "--format=volume" option,does that mean the whole disk will be formatted into one partition or some what like HD1.1 ,HD1.2? I'm confused. i never installed hotfix using image2disk (i usually use b software or tmsh install sys software command). anyway, normally --format will format whole hard disk (not only one partition).
sol12513: Installing hotfixes using the image2disk utility does not return the status of the installation
http://support.f5.com/kb/en-us/solutions/public/12000/500/sol12513.html
sol11033: Managing BIG-IP version 10.1.x and 10.2.x hotfixes on systems using the partitions disk formatting scheme
http://support.f5.com/kb/en-us/solutions/public/11000/000/sol11033.html