I have 2 units of PIX 515E. Both have same software version, same number and type of interfaces, activation key type, flash memory and amount of RAM.
But the encryption hardware device is different. One is having VAC+ (Crypto5823 revision 0x1) , the other one is having IRE2141 with 2048KB, HW:1.0, CGXROM:1.9, FW:6.5.
Can I setup failover with these 2 units?
Those VAC cards are EOL:
PIX515E is also EOL:
You might consider getting ASA firewalls.