Yes, these new disks have the WWN on them but the old ones didn't. While doing the identification I made a list as you suggest in there for next time. Unfortunately I only have 6 bays and they are all full which is why I had to go this way instead of adding an extra one and then removing the old one. Good to know that I don't have to scrub because the resilver is about eight hours to complete. I would have done it if necessary because better safe than sorry. I was only using iostat as an inventory tool. The disk had reported too many errors. This wasn't the first time it had done that and given they are about eight years old I decided it was time to bite the bullet and got some replacements that are larger anyway. Once I do the entire pool I will expand it. I can't get Smartmontools to install because I am on Solaris 11.3 and it does the dummy spit about the certificate when I try to install it. Once I have the pool sorted out I am going to do a reinstall of Solaris 11.4 and clean it all up. This was my first Solaris install and I have learned a lot along the way which has been fine but I have been putting this off for a long time and now the time has come.