Large Files in /scratch¶
The data containers in Lustre are called object storage targets (OST). The capacity of one OST is about 21 TB. All files are striped over a certain number of these OSTs. For small and medium files, the default number is 2. As soon as a file grows above ~1 TB it makes sense to spread it over a higher number of OSTs, e.g. 16. Once the filesystem is used >75%, the average space per OST is only 5 GB. So, it is essential to split your larger files so that the chunks can be saved!
Lets assume you have a directory where you tar your results, e.g.
/scratch/marie/tar. Now, simply
set the stripe count to a higher number in this directory with:
marie@login$ lfs setstripe -c 20 /scratch/ws/marie-stripe20/tar
This does not affect existing files. But all files that will be created in this directory will be distributed over 20 OSTs.
Useful Commands for Lustre¶
These commands work for
Listing Disk Usages per OST and MDT¶
marie@login$ lfs quota -h -u username /path/to/my/data
It is possible to display the usage on each OST by adding the argument
Listing Space Usage per OST and MDT¶
marie@login$ lfs df -h /path/to/my/data
Listing inode usage for an specific path¶
marie@login$ lfs df -i /path/to/my/data
marie@login$ lfs osts /path/to/my/data
View Striping Information¶
marie@login$ lfs getstripe myfile marie@login$ lfs getstripe -d mydirectory
-d will also display striping for all files in the directory.