It is always best to use the internal storage of the Astronomy Cluster, however, sometimes users like to use external hard drives.

If you are going to attach a external hard drive to your desktop - please make sure that it is formatted corrected for a Linux environment (usually it should be formatted as ext3 for Linux). NTFS or FAT32 formatted hard drives might cause issues.

In order to mount the disk -

1) plug in the external hard drive. 2) figure out what the desktop is seeing the disk as - *should* be /dev/sdb, but check! (you can check with the commands df or lsblk) 3) use the mount command:

mount /dev/sdb /mnt1

(where /mnt1 is a mount point - you can create and mount anywhere, but best to just keep with the mount points)

Then you can cd to the new mounted location and see your data!

There are several Mac and OSX users in the department. As such it is common that some people may have a Mac external hard-drive. These are usually formatted as hfsplus and are usually “journaled”. A drive that is “journaled” keeps a change log. Usually these are NOT compatible with Linux or MS environments as its the Mac OSX which is tracking changes to this external drive.

We are able to mount these drives on the cluster, HOWEVER, these drives will be automatically mounted as read-only. Root (accessible only by the Sys Admins) is able to force these drive to mount as read-write. HOWEVER, this comes with a non-zero risk of data loss. Since the drive is keeping a change-log via Mac OSX, if a different OS makes changes to it, there is a possibility that the change-log / data will be corrupted.

Use of this type of file formatted drive on the cluster is highly discouraged.

“Journaled” hard-drives are not unique to Mac OSX environments, and its possible that external hard-drives in Windows / Linux environments might also be “journaled”, but are less common.

Sometimes it is possible to turn off this “journal” feature.