lazear@gateway.mitre.org (03/06/89)
We have a 3/260 with a Xylogics 451 controller and two Super Eagle drives running 3.4 in our production mode. In our test mode we have replaced the two Eagles with another single drive that has 4.0 filesystems on it. We have found several instances where it would be great to be able to reference BOTH the 3.4 and 4.0 filesystems without recabling and rebooting. Does anyone have experience mounting BOTH AT THE SAME TIME? If it can be done, which kernel should we use (3.4 or 4.0)? Note that we can mount the "odd" file system as read-only, if that helps. Ideally, we'd like to mount the 4.0 filesystem on a 3.4 kernel running (so we can compare while running production users), but will settle for the other way around if need be. Walt (Lazear@gateway.mitre.org)
miker@oddjob.uchicago.edu (Mike Raffety) (03/23/89)
We have had a fair amount of success with a similar situation, taken a step further. Here's what we've got: A Sun-3/260 pedestal, with a disk pedestal with two Fujitsu-M2333 drives on a Xylogics 451. There's a Sun-3 SunOS 3.5 root on xy0a, swap on xy0b, /usr on xy0g, and another (local use) filesystem on xy0d. Now, on xy1a, there's a Sun-4 SunOS 4.0 root, with a vmunix set to use xy1a for root and swap on xy0b (no point in having TWO swap partitions, especially at 50 MB each, right?) and /usr on xy1g. When we want to have a Sun-4, we just swap the CPU cards ... the EEPROM on the Sun-4 is set to boot xy1a, instead of xy0a, so it's very simple and foolproof. We've been able to crossmount the filesystems from the different architectures and different versions of SunOS pretty well, except if we mount the Sun-4 SunOS 4.0 filesystem under the Sun-3 SunOS 3.5 architecture, attempting to delete a file panics the kernel (oops!). It certainly works on a read-only basis. Also, the machine has 56 MB of main memory ... a standard 32 MB Clearpoint card, and three Sun 8 MB cards. If your CPU is a 1206 part, revision level 10 or higher (look for the first number written with grease pencil on the external serial number tag), you can plug in 32 MB cards, and get a total of 128 MB main memory. Configure the 32 MB cards like you would for a Sun-4, and away you go.