Disk reservation

See also: Storage overview | Storage Manager | Group Storage | Ceph | Local (on nodes) disks reservation

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

You can 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

When a job of type deploy starts, the disks you reserved are enabled by the RAID card of the node, and the other disks are disabled. Thus, reserved disks can only be accessed by the user who reserved them.

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:

fnancy:

oarsub -I -t deploy -l {"cluster='grimoire'"}/host=1

Or reserve a node with all its disks:

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. At present, bookable disks are only present on the grimoire cluster.

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

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

You can decide to reserve some disks for one week, and the corresponding nodes only when you want to carry out an experiment.

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

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

Specify you want the first two disks of grimoire-2:

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:

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 in the usual way nodes grimoire-1 and grimoire-2 for 3 hours:

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 your home directory, your data on the disks will not be 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

Unfortunately, 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.