Cluster File System and Storage

Tip

If you have data stored in an Amazon S3 bucket, then you can use datastores in MATLAB to directly access the data without needing any storage on the cluster. For details, see Transfer Data To Amazon S3 Buckets. You can also select the following storage options when creating your cluster.

• Cluster Shared Storage

  • Persisted Storage. To request shared disk space that remains after you shut down the cluster, select a disk size. The shared storage is mounted at /shared/persisted. For details, see the table below.

  • Amazon S3 Data. To transfer individual files from an Amazon S3 bucket to the cluster machines, click Add Files. You can specify S3 files only when creating your cluster and starting it for the first time. When the cluster starts up, files are copied to /shared/imported. See Copy Data from Amazon S3 Account to Your Cluster.

• Local Machine Storage

  • Volume Size: To request an Amazon EBS Volume, enter a number of GB in the box, e.g. 100. This requests a local SSD, created on each worker machine of your cluster. The SSD is mounted at /mnt/localdata. Use this option when read/write performance is critical.

  • EBS Snapshot ID: If you previously saved an EBS snapshot of your data on Amazon, then enter the ID. The data is copied to the SSD volume attached to each worker machine. If you provide a formatted snapshot, then the file system type must be ext3, ext4, or xfs. For ext3 and ext4, the full volume size of the file system might not be immediately available when the instance comes online. Growing the file system to full capacity can take up to 30 minutes after the instance is online, depending on the size of the extN volume and the instance type. You can access all data in the original snapshot as soon as the cluster is online.

After selecting your storage options, click Create Cluster. For details on other cluster settings, see Create a Cloud Cluster.

All worker machines have access to local and cluster shared storage. You can use these folders for storing data generated by your jobs, and for data you want to transfer between the cluster and your client location. See Transfer Data to or from a Cloud Center Cluster. The paths are the same for all worker machines of the cluster. Changes to files and folders under /mnt/localdata are not visible to other machines. Files and folders under the /shared mount point are shared by all worker machines of your cluster. Changes made by any machine are visible to all other machines. Each folder has different longevity, as shown in the table.

Location	Size	Usage
/mnt/localdata	Specified in cluster configuration	The location of the local machine storage volume. Each worker machine gets its own copy of the data. Temporary and intermediate data can also be written to this location. Deleted when cluster is stopped. The data is not retained between cluster runs. If you have specified an EBS snapshot, then the data is copied again when the cluster is started.
/shared/persisted	Specified at cluster creation	The location of the cluster shared persisted storage and MATLAB Job Scheduler data. This folder is shared among worker machines and is retained between cluster runs. Save data you want to retrieve on the next start of the cluster in folders and files under /shared/persisted. Deleted when cluster is deleted.
/shared/tmp	Varies with instance type	This folder is shared among worker machines and is not retained between cluster runs. Use it to store temporary and intermediate data that must be visible or accessible from multiple cluster machines. The available storage space depends on the ephemeral storage available on the selected machine instance type. Deleted when cluster is stopped.
/shared/imported	Part of allocation for /shared/tmp	The location of the cluster shared Amazon S3 data. Selected Amazon S3 objects are copied to this location as part of the cluster start up and are deleted on shut down. Deleted when cluster is stopped; copied again when cluster is started.

Note:

• To use /shared/tmp or /shared/imported, you must disable the dedicated headnode mode (see Use a Dedicated Headnode Instance for Management Services), and use an instance with ephemeral storage. Consult the table in Choose Supported EC2 Instance Machine Types to find out which instances have ephemeral storage.

• Cloud cluster machines can share these folders only with machines of the same cluster; that is, there is no file sharing between different clusters.

• You create, start, stop, and delete your cloud clusters independent of your local MATLAB^® session. Deleting an associated cluster object in MATLAB does not affect the cloud cluster or its persistent storage.

• When a cluster times out, it shuts down and clears the contents of /shared/tmp, /shared/imported and /mnt/localdata, but preserves the content of /shared/persisted. If you use an automatic shutdown setting for your cluster, ensure that you have all data you need from /shared/tmp and /mnt/localdata before this timeout occurs.

• The contents of /shared/tmp are built using ephemeral storage.

Related Topics

• Create and Discover Clusters