Disk reservation

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Disk reservation is available for beta testing on the grimoire cluster in Nancy. Grimoire has eight nodes with five bookable disks on each node.

It is possible to reserve hard disks, in order to store large datasets between your nodes reservations for example (and avoid moving data to nodes at the beginning of each nodes reservations).

How it works

Disk reservation works with jobs of type noop and jobs of type deploy. You can reserve some disks in the long run with a job of type noop. Then, you may reserve the nodes where your disks are located with a job of type deploy. When the job of type deploy starts, the disks you reserved are enabled by the RAID card of the node, and the other disks are disabled. Reserved disks can only be accessed by the user who reserved them (see also Security issues).

Main commands

The main commands to reserve disks are given below. Note that disk reservation only works with a node reservation of type deploy. Additionally, by default, reserving a node on grimoire will only grant access to the main disk (additional disks need to be reserved).

The maximum duration of a disk reservation is defined in the Usage Policy.

Reserve disks and nodes at the same time

Reserve a node with its main disk on grimoire cluster:

Terminal.png fnancy:
oarsub -I -t deploy -l {"cluster='grimoire'"}/host=1

Or reserve a node with all its disks:

Terminal.png fnancy:
oarsub -I -t deploy -l {"type='disk' or type='default' and disk_reservation_count > 0"}/host=1

disk_reservation_count is equal to the number of bookable disks on a node.

Reserve nodes grimoire-1 and grimoire-2 with 1 disk per node:

Terminal.png fnancy:
oarsub -I -t deploy -l {"type='default' and host in ('grimoire-1.nancy.grid5000.fr','grimoire-2.nancy.grid5000.fr')"}/host=2+{"type='disk' and host in ('grimoire-1.nancy.grid5000.fr','grimoire-2.nancy.grid5000.fr')"}/host=2/disk=1

Reserve disks and nodes separately

First : reserve the disks

For example, you may decide to reserve some disks for one week, and the corresponding nodes only when you want to carry out an experiment. Jobs of type noop are used to reserve disks. They cannot be interactive and are necessarily reserved in advance.

Reserve two disks on grimoire-1 for one week, starting on January 1st 2018:

Terminal.png fnancy:
oarsub -r "2018-01-01 00:00:00" -t noop -l {"type='disk' and host='grimoire-1.nancy.grid5000.fr'"}/host=1/disk=2,walltime=168

Reserve the first two disks of grimoire-2:

Terminal.png fnancy:
oarsub -r "2018-01-01 00:00:00" -t noop -l {"type='disk' and host='grimoire-2.nancy.grid5000.fr' and disk in ('1', '2')"}/host=1/disk=2,walltime=168

Or reserve all disks of two nodes:

Terminal.png fnancy:
oarsub -r "2018-01-01 00:00:00" -t noop -l {"type='disk' and cluster='grimoire'"}/host=2/disk=ALL,walltime=168

Secondly: reserve the nodes

You can reserve nodes grimoire-1 and grimoire-2 for 3 hours, in the usual way:

Terminal.png fnancy:
oarsub -I -t deploy -l {"host in ('grimoire-1.nancy.grid5000.fr', 'grimoire-2.nancy.grid5000.fr')"}/host=2,walltime=3

Data loss

Such as for the /home directories, data on the disks are not backuped by Grid'5000. You must be cautious : several events such as a disk failure or a bad command on the node may delete your data.

Security issues

Grid'5000 being a platform of the type "hardware as a service", it is not possible to avoid a malicious user to take control of the RAID card and therefore of the disks. If you have sensitive data and don't know how to protect them, you may contact the Grid'5000 technical team to help you. It is also your responsibility to erase the data on the disks you reserved, at the end of your experiment.