Anyone else experiencing beachballs on El Capitan? I recently upgraded, and reinstalled OpenZFS 1.5.2 for the El Capitan version, and this is my first time running a back-up to my array, which I do once a month or so, but I seem to be getting the spinning beachball and lockups in apps fairly frequently (every 10 minutes or so).
My array isn't very optimal, I have two five-disk enclosures connected by USB3, mirroring each pair of drives between the two (i.e- the first drive of each array is a mirror, the second in each mirrored and so-on). The drives are mostly old spare drives of matching sizes (across each mirror), and I really just use it as an extra back-up run once a month, plus it lets me tinker with ZFS in advance of maybe someday using it for a main volume in future. Still, I've never experienced lock-ups like this under Yosemite, and there don't appear to be any major health issues with any of the drives.
CPU usage doesn't spike or anything when this happens (or if it does Activity Monitor/iStat Menus don't update in time to show it) and I have plenty of RAM free for ZFS to use if it wants to (with no restrictions in place other than whatever the defaults are).
At the current moment Time Machine isn't even copying anything, it just seems to be checking loads of files, which seems to be a side-effect of the update to El Capitan (I had to inherit the backup) so it's got over a million files to verify that may have changed since last month. I don't know what this stage involves exactly, probably lots of stat calls and comparison to local files?
Any ideas what might cause lock-ups? It's especially disruptive to anything with audio since I have an external USB sound card, not sure why it's being disrupted though since it has its own USB port all to itself, but my mouse and keyboard (also USB) aren't affected, except that apps like Safari are sometimes locking up briefly, delaying typing till they unfreeze.
If it's my own fault mainly for hurling a load of old drives into a shoddy enclosure then I can live with it, if this backup ever finishes the next one should be fast again, but I find it weird that this seems to happen more on El Capitan. It very occasionally happened on Yosemite, but definitely not as often as this.