The National Institute for Computational Sciences


General: What should I do in the event of a lustre slowdown?

In the event of a lustre slowdown, there are many things to consider as lustre has many working parts and is shared by all users on the system. NICS continually monitors lustre's performance and seeks to improve researcher's data communications. If you notice your code's I/O performance or the lustre filesystem is slower than usual, please answer the following questions to the best of your knowledge and email XSEDE Help Desk your answers.

General: Is there any other faster way to list my files in my Lustre scratch area?

Yes! A basic ls only has to contact the meta-data server (MDS), not the object-storage servers (OSS), where the bottleneck often occurs. In general, ls is aliased to give additional information, which requires the OSS's. You can bypass this by using /bin/ls. When there are many files in the same directory, and you don't need the output to be sorted, /bin/ls -U is even faster.

General: What is the default striping for my files?

A file's striping is inherited from its parent directory. The lfs getstripe command can be used to determine the striping for a file, or the default striping for a directory. Note that each file and directory can have its own striping pattern. This means that a user can set striping patterns for his own files and/or directories. The default stripe width for a user may be 1 or 4, you can determine by running lfs getstripe /lustre/medusa/$USER.

This command will also give you information on the striping information for a directory/file.

General: What is file striping?

The Lustre file system is made up of an underlying set of file systems called Object Storage Targets (OST's), which are essentially a set of parallel IO servers. A file is said to be striped when read and write operations access multiple OST's concurrently. File striping is a way to increase IO performance since writing or reading from multiple OST's simultaneously increases the available IO bandwidth.

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