Network Attached Storage

Network attached storage (NAS), sometimes simply called “the file server” is a place we can store large amounts of data that is administered by the Steward Observatory Computer Support Group for common use.

The Steward NAS is on the Steward wired network at ( exposed over SMB/CIFS. Currently (May 2023), we are allocated 15 TB of space.

Using the Steward NAS

The easiest way to use the Steward NAS is to copy files on a MagAO-X machine to /srv/nas. This path hooks up to the jrmales0 “share” on the NAS. The files will then be visible on any other computer with the /srv/nas mount. For organization, make a /srv/nas/users/<your username> folder to hold your files.

You can also access the share from your own computer, as described in the next section.

Connecting your own computer to the Steward NAS

Your first step should be to install Tailscale for secure connection tunnels following instructions for your operating system. Then, to connect:

macOS: On macOS, open Finder and then go to the “Go” menu and select “Connect to Server…” (alternatively, hit command-K). The top text box accepts a URL for connection, which should be smb://YOURNETID@ where YOURNETID is, well, your NetID from University of Arizona. You can “favorite” the url using the “+” button at lower left. Click “Connect”. You will be prompted for a password, which is just your NetID password.

This will pop open a window with the contents of the jrmales0 share on the NAS. You’ll also have a new entry in the sidebar of your Finder window labeled (Clicking that takes you to the top level list of shares, from which you can drill down into jrmales0.)

You can also drag icons from the Finder onto a terminal to get their full path, so you can do things like:

% fitsheader /Volumes/jrmales0/obs/2023A/2023-03-08_09/

This lets you view the header of a file without explicitly copying it to the local machine first.

Linux: You may need to install additional tools to access CIFS/SMB shares from Linux. These are usually called something like “samba” or “cifs-utils”. Consult documentation for your Linux distribution or the ever-helpful Google.

Windows: Open a Windows Explorer window (e.g. your Documents folder) and click in the address bar. Type in \\\jrmales0 to make a login window appear. In the username field, enter, and in the password field use the NetID password. Upon successful authentication, the window will show the contents of the jrmales0 share on the Steward NAS.

Connecting a server to the Steward NAS

Assuming a CentOS-like Linux server, you will need to install CIFS tools to get mount.cifs:

sudo yum install cifs-utils

Or, on Ubuntu:

apt install cifs-utils

Make a new file in /root and lock down its permissions:

sudo su
touch steward_nas.credentials
chmod 0600 steward_nas.credentials

Now, edit the file you just created. Within steward_nas.credentials the only contents should be:


The current password for the ASTR-MagAO-X service account is obtainable from the Computer Support Group or another server’s /root/steward_nas.credentials file (if accessible).

Next, create the mountpoint at /srv/nas:

mkdir -p /srv/nas

These instructions are designed for a MagAO-X machine, with an xsup user account and magaox user group. Obtain the numerical uid and gid for these entities:

# id xsup
uid=1000(xsup) gid=1000(xsup) groups=1000(xsup),10(wheel),100(users),1011(magaox),1012(magaox-dev)

Finally, put the mount information (and the large number of mount options) into /etc/fstab. The line below should be modified to replace uid=1000,gid=1011 with the numbers from the last step, if different. These options have the effect of making every file appear to be owned by xsup/magaox, with permissions for all magaox group users to modify it. (This is necessary because the user database on MagAO-X is separate from the University of Arizona directory.)

//  /srv/nas  cifs  noauto,x-systemd.automount,nofail,x-systemd.device-timeout=10s,,vers=default,credentials=/root/steward_nas.credentials,uid=1000,gid=1011,forceuid,forcegid,file_mode=0660,dir_mode=0770  0 0

This specifies that /srv/nas should point to //, the per-group folder we were given in the Steward NAS. The options noauto,x-systemd.automount,nofail,x-systemd.device-timeout=10s, try to minimize the annoyance of (re-)booting the machine in a situation where it cannot reach

Use systemctl daemon-reload and then systemctl start srv-nas.automount. Check if the mount came up by doing ls /srv/nas:

[root@exao0 ~]# ls -la /srv/nas
total 55705
drwxrwx---. 2 xsup magaox         0 Apr 24 09:43 .
drwxr-xr-x. 3 xsup magaox        17 Apr 17 16:58 ..
drwxrwx---. 2 xsup magaox         0 Apr 24 09:43 fits
drwxrwx---. 2 xsup magaox         0 Apr 24 09:38 obs