(Message inbox:1172) Return-Path: billb@JASON Received: by JASON (5.15/4.7) id AA22845; Wed, 26 Mar 86 13:32:26 EST Received: by ATHENA (5.45/4.7) id AA26307; Wed, 26 Mar 86 13:32:11 EST Received: by JASON (5.15/4.7) id AA22836; Wed, 26 Mar 86 13:31:47 EST Message-Id: <8603261831.AA22836@JASON> To: lbm@JASON Subject: Additional notes Date: Wed, 26 Mar 86 13:31:38 -0500 From: Bill Bryant The Problem of Limited Disk Space. Users of the development MicroVAXes will be able to store their files in two places: The home directories of their timesharing accounts; and, Their home directory on the MicroVAX. Home directories on a MicroVAX are stored on the /site/mit directory on the machine's hard disk. This directory does not have much space in it, and the space that it does offer must be backed up. You should encourage your developers to store their files in timesharing accounts and copy over files to the MicroVAX only when they need to work on them, making sure to copy them back to the timesharing machine when they have completed their work. Disk space in the /site directory is at a premium, and should be watched closely. Someone in the development group should make sure that people don't exhaust the disk space by leaving extraneous files in their home directories. Also be aware that the system itself has several files in the /site directory that it writes information into. These files grow a little bit each day. Ideally, the cron utility would check all the files on the system, remove extraneous ones, and prune those files that grow. You can check disk space usage manually with the df and du commands. When you use the df command without arguments: df The system displays information like this: Filesystem total kbytes kbytes percent node kbytes used free used Mounted on /dev/ra0a 7445 6243 457 93% / /dev/ra0g 5225 1855 2847 39% /site The percentage listed for the / directory should remain constant. The percentage listed for the /site directory will fluctuate. If it creeps up to 90%, you will want to remove and/or prune files immediately. Files that Tend to Grow In particular, you should monitor the size of two files in the /site/usr/adm directory: the acct file and the messages file. These files grow because the Unix accounting software updates them with regularity. acct is a particularly quick grower. The accounting software writes information into this file each time the system completes the execution of a process. It can expand as much as 12 kbytes a day. Don't remove the file. Prune it with the following command: cat /dev/null > /site/usr/adm/acct (You must be logged in as the superuser to run this command.) Also keep track of the messages file. You can prune it in the same way: cat /dev/null > /site/usr/adm/messages The shutdownlog file also grows, but it doesn't grow quickly unless you are shutting down the machine several time a day. You cam monitor users's disk consumption with the du command. Again, you should be logged in as the superuser to do things easily. Change directories to /site/mit, and type: du -s This command displays the total number of kbytes used by the directory. If you use du without the -s option, the command will display the total number of kbytes, and will descend into all subtrees and tell you how much diskpace each subdirectory consumes. The Problem of Limited Disk Space. Users of the development MicroVAXes will be able to store their files in two places: The home directories of their timesharing accounts; and, Their home directory on the MicroVAX. Home directories on a MicroVAX are stored on the /site/mit directory on the machine's hard disk. This directory does not have much space in it, and the space that it does offer must be backed up. You should encourage your developers to store their files in timesharing accounts and copy over files to the MicroVAX only when they need to work on them, making sure to copy them back to the timesharing machine when they have completed their work. Disk space in the /site directory is at a premium, and should be watched closely. Someone in the development group should make sure that people don't exhaust the disk space by leaving extraneous files in their home directories. Also be aware that the system itself has several files in the /site directory that it writes information into. These files grow a little bit each day. Ideally, the cron utility would check all the files on the system, remove extraneous ones, and prune those files that grow. You can check disk space usage manually with the df and du commands. When you use the df command without arguments: df The system displays information like this: Filesystem total kbytes kbytes percent node kbytes used free used Mounted on /dev/ra0a 7445 6243 457 93% / /dev/ra0g 5225 1855 2847 39% /site The percentage listed for the / directory should remain constant. The percentage listed for the /site directory will fluctuate. If it creeps up to 90%, you will want to remove and/or prune files immediately. Files that Tend to Grow In particular, you should monitor the size of two files in the /site/usr/adm directory: the acct file and the messages file. These files grow because the Unix accounting software updates them with regularity. acct is a particularly quick grower. The accounting software writes information into this file each time the system completes the execution of a process. It can expand as much as 12 kbytes a day. Don't remove the file. Prune it with the following command: cat /dev/null > /site/usr/adm/acct (You must be logged in as the superuser to run this command.) Also keep track of the messages file. You can prune it in the same way: cat /dev/null > /site/usr/adm/messages The shutdownlog file also grows, but it doesn't grow quickly unless you are shutting down the machine several time a day. You cam monitor users's disk consumption with the du command. Again, you should be logged in as the superuser to do things easily. Change directories to /site/mit, and type: du -s This command displays the total number of kbytes used by the directory. If you use du without the -s option, the command will display the total number of kbytes, and will descend into all subtrees and tell you how much diskpace each subdirectory consumes. Don't put your MicroVAX name in a timesharing .rhosts file! If you do so, you compromise the security of your account on that timesharing system, as well as any other accounts you can access through that account. At this time, it is very easy for someone to change the name of a MicroVAX to match a name in a .rhosts file. Someone could do this, masquarade as your machine name, and break into your account on the timesharing machine.