I just had a strange experience that there is probably a simple explanation for.
I connected to a shared volume on my 10.14 desktop using my 10.14 based laptop via SMB. It initially seemed like there was something wrong with the server, because it was unusably slow.
When I looked at Activity Monitor, I was seeing erratic download traffic from 2 to 10MB/s. All of it was kernel_task. There was only a single Finder window with maybe 10 documents open from the server, and they had no preview icons, so it wasn't previews loading. I waited a couple of minutes but the traffic continued, and an attempt to copy a few files to the server hung on "preparing to copy" for at least a minute.
I eventually tried disconnecting from the server, at which point the traffic stopped. I reconnected, and it worked like you'd expect--quick response and no unexplained traffic. The same folder didn't do anything unusual, confirming it wasn't Finder trying to generate preview icons or the like.
What the heck was going on here? My best guess is Quicklook freaked out and was repeatedly downloading something or trying to generate a preview of something huge that I wasn't looking at anymore.
I would just write it off but I realize in hindsight this explains why I have occasionally had random trouble with slow server network access in the past, I just didn't realize what the cause was because I didn't poke at it. Is there a way to get more granular info about where network traffic is coming from or going to?
I connected to a shared volume on my 10.14 desktop using my 10.14 based laptop via SMB. It initially seemed like there was something wrong with the server, because it was unusably slow.
When I looked at Activity Monitor, I was seeing erratic download traffic from 2 to 10MB/s. All of it was kernel_task. There was only a single Finder window with maybe 10 documents open from the server, and they had no preview icons, so it wasn't previews loading. I waited a couple of minutes but the traffic continued, and an attempt to copy a few files to the server hung on "preparing to copy" for at least a minute.
I eventually tried disconnecting from the server, at which point the traffic stopped. I reconnected, and it worked like you'd expect--quick response and no unexplained traffic. The same folder didn't do anything unusual, confirming it wasn't Finder trying to generate preview icons or the like.
What the heck was going on here? My best guess is Quicklook freaked out and was repeatedly downloading something or trying to generate a preview of something huge that I wasn't looking at anymore.
I would just write it off but I realize in hindsight this explains why I have occasionally had random trouble with slow server network access in the past, I just didn't realize what the cause was because I didn't poke at it. Is there a way to get more granular info about where network traffic is coming from or going to?