Oracle VM for SPARC, as it's now called, uses Logical Domain Channels (LDCs) for inter-domain communication of all sorts, mostly used for virtual devices. A question I've been asked multiple times was how many LDCs there are available, and how to tell how many you've used. Here a few notes to that:
VCCUse the additional option "-p" for parsable output. With that, the command ldm list-bindings -e -p|grep ldc=0|awk -F\\| '{print $NF}' will give you a brief list of all LDC IDs used. If you like, count them with wc
NAME PORT-RANGE
vconsole 5000-5050
CLIENT PORT LDC
debian@vconsole 5001 0x18
rivermuse@vconsole 5002 0x1c
gentoo@vconsole 5000 0x11
demo@vconsole 5008 0x3d
install@vconsole 5012 0x50
rac1@vconsole 5005 0x35
rac2@vconsole 5006 0x66
Knowing all this should help you planing your next virtualization deployment. The available number of LDCs should usually be sufficient. Using the formula from above, you can easily figure that even on T2, the singe socket system, a maximum of 124 domains is possible. On T2+, this goes to 193 - more than the supported 128 guests. Of course, you're likely to have more than the bare minimum of three devices per guest, so your actual maximum will vary. However, it should still be enough in most cases. And now, next time you're asked for an additional guest, you can quickly check and figure if you have enough LDCs available.
(This entry was updated on Feb. 19, 2013 and again on Jan 27, 2014)