For the past sev­eral weeks at work I’ve been grad­u­ally work­ing on upgrad­ing our OS X server from Leop­ard to Tiger. The process has cer­tainly not been with­out hic­cups, but it has gone smoothly for the most part.

After an ini­tial false start attempt­ing to simply upgrade the server, I ended up simply installing the Leop­ard server from a blank disk. This seemed to take care of most of the really strange things that were hap­pen­ing after the upgrade.

This par­tic­u­lar server is of the head­less XServe vari­ety, so we pri­mar­ily use Apple Remote Desk­top to access it in addi­tion to the Server Admin Tools and SSH. Since installing Leop­ard on the server how­ever, I’ve been notic­ing that at times it is acting errat­i­cally. Usu­ally I’ll first notice that the server will either stop show­ing up in ARD or it show up as black, indi­cat­ing that there is no ARD agent on the com­puter. I’ve tried restart­ing the com­puter, which will fix it, but that’s not a very good solu­tion for obvi­ous reasons.

I had also noticed while using Server Admin that some­times the server CPU is run­ning at com­pletely full capac­ity, like in this screenshot:

The other day the server stopped respond­ing in ARD again. As usual though, I was still able to access it through both Server Admin and SSH. After a little research, I found this useful page of com­mands, which includes this one-​liner:

sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -restart -agent -menu

Run­ning this com­mand restarts the ARD Agent, which is what we want if it is frozen. Once I did this things got a little better, and the server came up in ARD as active. I tried con­trol­ling the server through ARD, but no dice, still no connection.

At this point I noticed that there was a user logged on to the server and I remem­bered that I had also been having prob­lems with VNCDragHelper freez­ing. I found this on an Apple dis­cus­sion page:

When remotely man­ag­ing an XServe with OS 10.5.1 from a 10.4.11 client with ARD 3.2, sev­eral times (3 up till now) the server UI becomes unre­spon­sive, at least finder. This even gets worse when trying to start the Appli­ca­tion Mon­i­tor, then also the Dock freezes, and the Appli­ca­tion Mon­i­tor UI never opens. When doing an ssh> sudo top, it shows that both “Application Monitor” and “VNCDragHelper” do con­sume almost 100% CPU. Luck­ily only on a Single core, but that keeps two cores (one proces­sor 100% busy). kil­lall “Activity Monitor” brings the activ­ity mon­i­tor down, when send­ing it with Remote Desk­top Unix command.

Per­fect, that must be it. In SSH, I ran the fol­low­ing command:

sudo killall -9 VNCDragHelper

I also killed the loginwindow because that appeared to be frozen as well (judg­ing from the top com­mand that I ran):

sudo killall -9 loginwindow

Sud­denly after run­ning both those com­mands, the server leapt back to respon­sive­ness. I was able to access it in ARD with­out prob­lem. Also, after about an hour I checked the CPU dia­gram in Server Admin and was able to see a notice­able improvement.

Now that’s a sight for sore eyes. For ref­er­ence, I was run­ning 10.5.3 and ARD 3.1 when this prob­lem hap­pened. I’m not sure that any­thing has been fixed in 10.5.4 though.