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Revision as of 11:15, 17 November 2014 by Merz (Talk | contribs) (A MUCH NEEDED UPDATE. !!!!!)

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Getting Help

I have encountered a problem while using a SHARCNET system and need help, who should I talk to?

If you have access to the Internet, we encourage you to use the problem ticketing system (described in detail below) through the web portal. This is the most efficient way of reporting a problem as it minimizes email traffic and will likely result in you receiving a faster response than through other channels.

You are also welcome to contact system administrators and/or high performance technical computing consultants at any time. You may find their contact information on the directory page.

How long should I expect to wait for support?

Unfortunately SHARCNET does not have adequate funding to provide support 24 hours a day, 7 days a week. User support and system monitoring is limited to regular business hours: there is no official support on weekends or holidays, or outside 9:00 - 17:00 EST .

Please note that this includes monitoring of our systems and operations, so typically when there are problems overnight or on weekends/holidays system notices will not be posted until the next business day.

SHARCNET Problem Ticket System

What is a "problem ticket system"?

This is a system that allows anyone with a SHARCNET account to start a persistent email thread that is referred to as a "problem ticket". The thread is stored indefinitely by SHARCNET and can be consulted by any SHARCNET user in the future. When a user submits a new ticket it will be brought to the attention of an appropriate and available SHARCNET staff member for resolution.

You can find the SHARCNET ticket system here, or by logging into our website and clicking on "Help" then "Problems" in the top left-hand-side menu.

How do I search for existing tickets ?

Type a meaningful string into the search box when logged into the SHARCNET web portal. You can find this text entry box beside the Go button on the top right-hand-side of the page in the web portal.

It is recommended that one use specific words when searching, for example the exit code returned in your job output, or the error message produced when attempting a command. Use of common search terms may produce too many results and this coupled with the lack of sophisticated ranking for results means your search will likely be misleading or time consuming if you have to sift through many results by hand.

What do I need to specify in a ticket ?

If you do not find any tickets that deal with you current problem (as illustrated above) then you should ensure you include the following information, if relevant, when submitting a ticket:

  1. use a concise and unique Subject for the ticket
    • this makes it easier to identify in search results, for example
  2. select sensible values for the System Name and Category drop down boxes
    • this helps guide your ticket to the right staff member as quickly as possible
  3. in the Comment text entry box:
    1. if the problem pertains to a job report the jobid associated with the job
      • this is an integer that is returned by sqsub when you submit the job
      • you can also find a listing of your recent jobs (including their jobid) in the web portal at the bottom of this page
    2. report the exact commands necessary to duplicate the problem, as well as any error output that helps identify the problem
      • if relevant, this should include how the code is compiled, how the job is submitted, and/or anything else you are doing from the command line relating to the problem
    3. if this ticket relates to another ticket, please specify the associated ticket number(s)
    4. if you'd like for a particular staff member to be aware of the ticket, mention them
  4. if you want to expedite resolution you can make your files publicly available ahead of time
    • you should include any relevant files required to duplicate the problem
    • if you're not comfortable with changing your own file permissions, in Comment you can request that a staff member provide a location where you can copy the necessary files, or arrange file transfer via other means. If your code is really sensitive you may have to arrange to meet in person to show them the problem.

How do I submit a ticket?

We recommend that you read the above section on what to specify in a ticket before submitting a new ticket.

Users can submit a problem ticket describing an issue, problem or other request and they will then receive messages concerning the ticket via email (the ticket can also be consulted via the web portal).

You can also open a ticket automatically by emailing help@sharcnet.ca with the email address associated with your SHARCNET account.

How do I give other users access to my files ?

There are two ways to provide other users with access to your files. The first is by changing the file attributes of your directories directly with the chmod command and the second is by using file access control lists (acl). Using ACLs is more flexible as it allows you to specify individual users and groups and their respective privileges, whereas using chmod is more coarse grained and only allows you to set the permissions for your group and global access. At present ACLs are only supported on the SHARCNET global work (/work) and home (/home) filesystems.

providing global access with chmod

The following instructions provide commands that you can use to make your files available to all SHARCNET users, including staff. It assumes that you are sharing files in your /home directory, but you can change this to /work or /scratch or etc. with the same effect.

In the below, instead of <your-subdirectory> , type the name of the subdirectory where the files you want to give access to are located:

(1) Go to your home directory by running:

       cd

(2) Authorize access to the home directory by running:

       chmod o+x  .

(3) Authorize access to <your-subdirectory> by running:

       chmod -R o+rX <your-subdirectory>

Note that if the directory you wish to share is nested multiple directories below your home directory (eg. you want to give access to ~/dir1/dir2, but not ~/dir1) you will have to run:

       chmod o+x .

in any of the intervening directories if they are not already globally accessible.

To restrict all public access due to these changes one can simply run the following commands:

       cd
       chmod o-x .

providing per-user/group access with setfacl

An Access Control List (ACL) is basically a list of users and groups with their associated file access privileges which is associated with a file/directory. At present ACLs are only supported on the SHARCNET global work (/work) and home (/home) filesystems.

One can see the ACL for a particular file/directory with the getfacl command, eg.

[sn_user@hnd50 ~]$ getfacl /work/sn_user
getfacl: Removing leading '/' from absolute path names
# file: work/sn_user
# owner: sn_user
# group: sn_user
user::rwx
group::r-x
other::--x

One uses the setfacl command to modify the ACL for a file/directory. To add read and execute permissions for this directory for user ricky, eg.

[sn_user@hnd50 ~]$ setfacl -m u:ricky:rx /work/sn_user

Now there is an entry for user:ricky with r-x permissions:

[sn_user@hnd50 ~]$ getfacl /work/sn_user
getfacl: Removing leading '/' from absolute path names
# file: work/sn_user
# owner: sn_user
# group: sn_user
user::rwx
user:ricky:r-x
group::r-x
mask::r-x
other::--x

To remove an ACL entry one uses the setfacl command with the -x argument, eg.

[sn_user@hnd50 ~]$ setfacl -x u:ricky /work/sn_user

Now there is no longer an entry for ricky:

[sn_user@hnd50 ~]$ getfacl /work/sn_user
getfacl: Removing leading '/' from absolute path names
# file: work/sn_user
# owner: sn_user
# group: sn_user
user::rwx
group::r-x
mask::r-x
other::--x

Note that if one wants to provide access to a nested directory then the permissions need to be changed on all the parent directories using the -R flag. Please see the man pages for these commands man getfacl; man setfacl for further information. If you'd like help utilizing ACLs please email help@sharcnet.ca.

I am new to parallel programming, where can I find quick references at SHARCNET?

SHARCNET has a number of training modules on parallel programming using MPI, OpenMP, pthreads and other frameworks. Each of these modules has working examples that are designed to be easy to understand while illustrating basic concepts. You may find these along with copies of slides from related presentations and links to external resources on the Main Page of this training/help site.

I am new to parallel programming, can you help me get started with my project?

Absolutely. We will be glad to help you from planning the project, architecting your application programs with appropriate algorithms and choosing efficient tools to solve associated numerical problems to debugging and analyzing your code. We will do our best to help you speed up research.

Can you install a package on a cluster for me?

Certainly. We suggest you make the request by sending e-mail to help@sharcnet.ca, or opening a problem ticket with the specific request.

I am in a process of purchasing computer equipment for my research, would you be able to provide technical advice on that?

If you tell us what you want, we may be able to help you out.

Does SHARCNET have a mailing list or user group?

Yes. You may subscribe to one or more mailing lists on the email list page available once you log into the web portal. To find it, please go to MyAccount - Settings - Details in the menu bar on the left and then click on Mail on the "details" page. Don't forget to save your selections.

Does SHARCNET provide any training on programming and using the systems?

Yes. SHARCNET provides workshops on specific topics from time to time and offers courses at some sites. Every June, SHARCNET holds an annual summer school with a variety of in-depth, hands-on workshops. All materials from past workshops/presentations can be found on the SHARCNET web portal.

SHARCNET also offers a series of online seminars. These are announced via the SHARCNET events mailing list and one can see the schedule at the SHARCNET event calendar. Past seminars are recorded, a full listing is in the Online_Seminars page.

How do I watch tickets I don't own?

There are two ways. First, to view the tickets of user "USERID", type the URL like below:

https://www.sharcnet.ca/my/problems/view?username=USERID

,where USERID is the user you want to see. In the "Actions" column, click on "watch" for problems that you want to follow. This should enable you to receive notifications if any of the problems you are "watching" are updated.

If you want to do the same thing for tickets posted by other members in your group, just access their userpage (listed on https://www.sharcnet.ca/my/users/show/361 )

The other way is to use 'search box' in the SHARCNET website. By typing the ticket number or userid, you can do similar thing described above.