Questions[resource-management](server)

Taking for example this hierarchy from systemd-cgls:

└─user.slice
  ├─user-1000.slice
  │ ├─[email protected]
  │ │ └─init.scope
  │ │   ├─3262 /lib/systemd/systemd --user
  │ │   └─3263 (sd-pam)  
  │ └─session-3.scope
  │   ├─3260 sshd: user1 [priv]
  │   ├─3362 sshd: user1@pts/1 
  │   ├─3363 -bash
  │   └─3378 ssh-agent -s
  └─user-0.slice
    ├─session-1.scope
    │ ├─3151 sshd: root@pts/0    
    │ ├─3252 -bash
    │ ├─3625 systemd-cgls

If I set a limit for user.slice, for example 5M of memory, the Memory line clearly report it:

systemctl status user.slice
● user.slice
   Loaded: loaded (/etc/systemd/system/user.slice; static; vendor preset: enabled)
   Active: active since Mon 2016-08-22 11:32:13 CEST; 52min ago
    Tasks: 12
   Memory: 3.1M (limit: 5.0M)
      CPU: 1.275s
   CGroup: /user.slice
...

The user-1000 slice have the limit applied, if I stress the system with this user I can see it. But the status don't report the limit in this child slice:

systemctl status user-1000.slice
● user-1000.slice - User Slice of user1
   Loaded: loaded (/run/systemd/transient/user-1000.slice; transient; vendor preset: enabled)
Transient: yes
   Active: active since Mon 2016-08-22 11:32:42 CEST; 1h 8min ago
    Tasks: 6 (limit: 12288)
   Memory: 856.0K
      CPU: 521ms

Following the proc way I can see that the user-1000 process belong to the user slice:

# cat /proc/3260/cgroup 
10:memory:/user.slice/user-1000.slice
...

And checking directly inside the /sys/:

root@server1:/sys/fs/cgroup/memory/user.slice# cat memory.limit_in_bytes 
5242880
root@server1:/sys/fs/cgroup/memory/user.slice# cd user-1000.slice/
root@server1:/sys/fs/cgroup/memory/user.slice/user-1000.slice# cat memory.limit_in_bytes 
9223372036854771712

How is possible to know if a child process/slice have a limit defined in a parent cgroup?

I've only basic Windows Server knowledge and I've inherited responsibility for a Terminal Server installation with 20-30 concurrent users (Windows Server 2003).

There are intermittent problems with performance - ultimately due to to the low spec of the server I think (triple core, 4Gb memory using PAE). I'm trying to see if I can keep things running before a major upgrade later on this year.

One thing I've noticed is that processes from various sessions often consume 100% of a core. I think the freezes happen when this occurs on several sessions at once. Is there anything I can do to limit the CPU use of individual sessions? Alternatively is it possible to reserve one core so that it is not used by individual sessions but is available to handle logins etc instead?

I have a long running process that is eventually going to hit the max open file limit. I know how to change that after it fails, but is there a way to change that for the running process, from the command line?

I'd like to be able to set up a default user quota for members of a group if they don't have a specific user quota defined. The idea is that by default, they'd have this standard quota but if a specific entry for them was made in the aquota.user file that specific quota would apply and override the default.

Is this even possible?

I work part time for a small private school. The 24 node computer lab kept having hardware failures (mostly drives and cooling fans) so I turned it into a Linux based thin client network. Although the workstations now boot from the network, most still have working hard drives. They also use only a fraction of their computing power to run an x server.

I'm looking for ways to but these computing resources to good use. Each workstation has a 40GB HDD, a Pentium 4 processor and 256M RAM.

I've considered:

• Installing a fault tolerant distributed file system on each of the workstations. This would make use of both the hard drive space and computing resources of each workstation and yet continued hardware failures would have minimal impact.
• Removing the hard drives and putting them in a couple of file servers. Running a distributed computing client on the workstations to take advantage of free CPU cycles. Ok, though I'm sure to find a place for a few more file servers, I'll admit I don't really have any application in mind for a distributed processing environment.

If you think the first idea has merit, I'd be interested in any information you can give on the various distributed file systems available. I did a bit of searching but couldn't find one that really fit the situation. I'm looking for redundancy and fault tolerance but it needs to have support for user and group level access restrictions as well.

Any other suggestions would be appreciated as well.