Another disk showed problems on cdsfs0, so I replaced it was a spare.

Cdsfs1 has numerous problems.  Zpool status is noting that sdl, sdh, sdp, sdo are bad.  It looks like the io slot for sdl may be bad (I tried replacing the disk and the system could not see it).  I replaced the sdh disk and got it resilvering.  Then sdp started resilvering (which was unexpected). I'm going to wait and see how this resilvering goes before I proceed.  The activity lights do not match my model of what zpool status is telling me.  This is an old box, and replacement/retirement may just be the better path for it.