HLRN NHR provides tailored WORK file systems for improved IO throughput of IO intense job workloads.

...

WORK is the default shared file system for all jobs and can be accessed using the $WORK variable. WORK is accessible for all users and consists of 8 Metadata Targets (MDT's) with NVMe SSDs and 28 Object Storage Targets (OST's) on Lise and 100 OST's on Emmy handling the data. Both using classical hard drives.

...

Some workloads will benefit of striping. Files will be split transparently between a number of OSTs.

Especially large shared file IO patterns will benefit from striping. Up to 28 OSTs on Lise and up to 100 OST's on Emmy can be used, recommeded recommended are up to 8 OSTs for Lise and 32 OSTs on Emmy. We have preconfigured a progressive file layout (PFL), which sets an automatic striping based on the file size.

Access: create a new directory in $WORK and set lfs setstripe -c <stripsize> <dir>

...

Some Compute Nodes are installed with local SSD storage up to 2 TB on Lise and 400 GB 480 GB or 1TB (depending on the node) on Emmy.

For unshared local IO this is the best performing file system to use.

FastIO

...

WORK is extended with 4 additional OST's using NVMe SSDs to accelerate heavy (random) IO-demands. To accelerate specific IO-demands further striping for up to these 4 OSTs is available.

Access: ask support@hlrn.de for access

Size: 55 TiB - quoted

IME - Emmy only

DDN Infinite Memory Engine (IME) based Burst Buffers is a fast NVMe Solid State Disk (SSD) based data tier. Like Lise's FastIO this is especially helpful for random IO (especially random read) on large files.

Using the Burst Buffer for random IO helps to avoid overloading the global filesystem which results in slow job runtimes for all users. Beside the POSIX interface a native API and a MPI-IO module for further acceleration is available.

IME servers are currently available for use in EMMY.

Access: ask support@hlrn.de for access

Size: 48 TiB

create a new directory in $WORK and set lfs setstripe -p flash <dir>

Size:

55 TiB - quoted

Finding the right File System

If your jobs have a significant IO part we recommend asking your consultant via support@hlrnsupport@nhr.zib.de to recommend the right file system for you.

...

If you have a significant amount of node-local IO which is not needed to be accessed after job end and will be smaller than 2 TB on Lise and 400 GB on Emmy we recommend using $LOCAL_TMPDIR. Depending on your IO pattern this may accelerate IO to up to 100%.

...

Global IO is defined as shared IO which will be able to be accessed from multiple nodes at the same time and will be persistent after job end.

Especially random IO on small files will be accelerated up to 200% using FastIO on Lise or IME on Emmy

INTERNAL - not public - will be deleted

Recommendation Matrix:

Max performance gain on IO versus default $WORK in brackets.

...

FastIO stripe=4       (+200%) or

$WORK stripe=4-8 (+200%)

...

FastIO stripe=4       (+80%)

$WORK stripe=4-8  (+70%)

...

FastIO stripe=4         (+120%)

$WORK stripe=MAX (+90%)

...

FastIO stripe=4         (+200%) or

$WORK stripe=MAX (+150%)

...

FastIO stripe=4         (+100%)

FastIO                        (+50%)

Commands

Striping einrichten

mkdir <dirname>

lfs setstripe -c <count> <dirname>

DoM einrichten

mkdir <dirname>

lfs setstripe -E 64K -L mdt -E -1 -p work.rotational <dirname>

FastIO einrichten

mkdir <dirname>

lfs setstripe -p flash <dirname>

Fastio mit Striping 4 einrichten:

mkdir <dirname>

lfs setstripe -p flash -c 4 <dirname>

Prüfen

lfs getstripe <dirname>

Vorschlag Ankündigung

...