Replace Larger HD For Raid 5

i have a msi server with three seagate HD,

and use seagate ST336607LC to do raid5.

the raid card is adaptec 2200S,

it is installed with centos with cpanel.

today,the websites shows 500 internal error and i asked the DC reboot,

minutes later,the websites run well.

but minutes later,it down again,and i ssh to reboot,

minutes,it shows file system problem,it seems readonly?...in my memory.

and i ask the DC to reboot again,

and i still can not login,and the DC staff tell me it shows with "operation system not found"...

and i go to DC,

it shows there is no logical drives... and operation system not found.

and i try to use ctrl+a to access raid control panel,

it shows there is no raid setting....

and i try to verify the hds in raid control panel,

it shows my 3rd hd has defect and ask if want to assign new block,

at begining,i chose no,it still can not load the os.

and then i chose yes to reassign the block and passing the verify,

but it still can not load the os.

i can not get any ST336607LC now,

i want to ask can i use larger HD to replace the 3rd hd?

if yes,after replacing and booting,

should i reset the raid configuation?