So Plex randomly started stuttering the other day. I believe I've narrowed it down to SHFS.  When Plex stutters, I log into unRAID and my CPU is running between 18 and 30% which shouldn't cause issues.  When I check running tasks SHFS is running and using anywhere from 40 to 80%.    NOthing is going on in the background other than Plex when this is occuring so I don't know what it's even doing. Is it running because Plex is recording to the cache pool?  No maintenace tasks are scheduled for these times, mover is not scheduled, there's no data transfers going on.. Plex runs off of my cache pool,  not writing or reading to the array.

 

So what is SHFS doing and why would it cause Plex to stutter?  IS there a way to make Plex a priority service to avoid these stutters?

Edited October 31, 20241 yr by slydog75

Plex can be resource intensive. you may have to much running at once on the system for plex to run stable. 

Please post diagnostics for further troubleshooting.

which docker image are you running for plex?

I don't think it's a resource issue, as I said my CPU isn't going over 30% usage and RAM is under 50%.   I"m using the official Plex docker currently.

 

I just noticed my CPU temp is being reported as hitting 100C when the stutters occur so I may have a cooling issue.  I'm going to try to repaste (this build is based off an older gaming PC) and install an upgraded heat sink while I'm at it.

 

I've also attached my diagnostics log. 

Thanks for your time.

ur-homeserver-diagnostics-20241031-0041.zip

A More experienced user may need to chime in on this one. Not sure what i'm looking at in the log here to help diagnose.

yeah you got some things in the log that may be a key into why it may be stuttering.

Oct 31 00:34:56 UR-HomeServer kernel: scsi_io_completion_action: 231 callbacks suppressed
Oct 31 00:34:56 UR-HomeServer kernel: sr 0:0:0:0: [sr0] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=DRIVER_OK cmd_age=0s
Oct 31 00:34:56 UR-HomeServer kernel: sr 0:0:0:0: [sr0] tag#0 Sense Key : 0x5 [current] 
Oct 31 00:34:56 UR-HomeServer kernel: sr 0:0:0:0: [sr0] tag#0 ASC=0x64 ASCQ=0x0 
Oct 31 00:34:56 UR-HomeServer kernel: sr 0:0:0:0: [sr0] tag#0 CDB: opcode=0x28 28 00 00 02 da e6 00 00 02 00
Oct 31 00:34:56 UR-HomeServer kernel: blk_print_req_error: 231 callbacks suppressed

quite a bit of that is going on.
?is plex playing form a disk drive?

the only thing on a disk drive is my actual media but these stutters are actually occuring while watching Live TV (with an HDHomeRun tuner).  I'll need to do some tests to see if it occurs while watching movies as well.  However, this didn't occur before I mgirated Plex to unRAID.  

OK, it appears I have this issue fixed.   First, my CPU was definitely overheating becuase there was a wire stuck in the fan.. so I think that was exacerbating the problem, but I don't think it was the root cause; even after fixing that, if I transfered a file to cache while plex was playing it would still stutter.

 

I changed the transcode path from /mnt/user/plex_transcode/ to /mnt/cache/plex_transcode/ (appdata had already been changed to this previously) and that seems to have done the trick. SHFS no longer starts hogging the CPU whenever plex is recording Live TV and the stutters seem to be gone!

Edited November 1, 20241 yr by slydog75