If you are not using VTP actively in your environment, it is recommended to configure your switches to use VTP transparent mode (vtp mode transparent). This will prevent any inadvertant VLAN learning from happening within the environment. Even if your switch is configured as a VTP server, if there is another VTP server in the same domain that is sending a higher config revision number, it will adjust its config with those settings.
That being said, if you change the mode to transparent but still have issues with vlan info not staying updated after reload, I suppose you could ensure your changes are being made to your vlan.dat file, which is where your VLAN info is stored. On a 6509 you should be able to do:
more const_nvram:vlan.dat
and it will output a hex / ASCII dump of the file. You should be able to read your ASCII dump of your vlan name (easiest change to make and validate is written). Except from vlan.dat below for example (Vlan ID 200 (0xC8); Vlan name Switch-Mgmt):
00000150: 00000000 0B537769 7463682D 4D676D74 .... .Swi tch- Mgmt
00000160: 00000000 00000000 00000000 00000000 .... .... .... ....
00000170: 00000000 00000101 05DC00C8 00018768 .... .... .\.H ...h
Hopefully this helps you in your troubleshooting.
Matt
