use ssd as write-journal or lvm-cache?

[d tbsky <tbskyd@gmail.com>]

Hi:
   I was to use ssd to cache my mdadm-raid5 + lvm storage. but I
wonder if I should use them as lvm-cache or mdadm write journal.
lvm-cache has benefits that it can do also read-cache. but I wonder if
full-stripe write is the key point I need. I prefer to use the ssd as
mdadm write journal. is there other reason I should use lvm-cache
instead of  mdadm write-journal?

ps: my ssd is intel dc grade, so I think enable write-back mode of
cache is not problem.