Accessing exported/shared filesystem directly from Control Station on VNX unified or file | Dansbo Tech Blog

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Accessing exported/shared filesystem directly from Control Station on VNX unified or file

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On all EMC VNX systems running as Unified or File, it is possible to access the exported/shared filesystems directly from the Control Station of the VNX without having the proper rights for the files.

In order to be able to do this, it is necessary to be able to login as root on the Control Station of the VNX. Start by connecting to the Control Station through SSH. Usually you should log in as the nasadmin user. By default, the password is also nasadmin.

Once logged in to the Control Station you mush switch to the root user by entering the su command. Again, the default password to become root is nasadmin.

– a short explanation of the VNX: The smallest File/Unified VNX system has 2 datamovers, 1 active and 1 passive or standby. They are called server_2 (active) and server_3 (standby). It is possible to have more than 2 datamovers, in which case there will be more than 1 active datamover. Each datamover is inserted in a slot that decides the datamovers initial number. This means that server_2 is placed in slot_2, server_3 in slot_3 and so on.

In order to get access to the filesystems that are used by the datamovers, you need to get them mounted to the Control Station. Fortunately this is easily done because the Control Station has a function to automount the filesystems of a datamover.

Datamover filesystems can be automaticly mounted to directories under /nasmcd/rootfs on the Control Station, but if you list the contents of /nasmcd/rootfs, you will find that it is empty. What you need to do is actually change to the directory of the datamover that you want to access.

Let us say that you want to access filesystems shared directly by server_2 or by a VDM (Virtual Data Mover) hosted on server_2, first you change to the correct directory:

cd /nasmcd/rootfs/slot_2

Even though the directory did not exist previously, it is automatically created and mounted when you change in to it. Now you can browse through alle the filesystems that are mounted by datamover server_2.

By default, the filesystem is mounted as read-only, but it is easy to get it mounted read/write.

mount -o remount,rw /nasmcd/rootfs/slot_2

Be WARNED!!! You now have root access to all files owned by the datamover which means you can modify and delete any and all files no matter the CIFS, NFS or FS settings.

When you are done accessing the files, you should unmount the directory. The VNX usually does this by it self after a timeout period, but I suggest unmounting manually.

umount /nasmcd/rootfs/slot_2

This information is provided because it is possible to get into situations where it is close to impossible to modify files as needed through exports or shares.

Use at your own risk, I take no responsibility for any damage or dataloss.

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