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4. Storage

4.1. Home Area

Home area is the disk area shared by each interactive and compute node, which is available to all ABCI users by default. The disk quota is limited to 200GiB.

Warning

In Home area, there is an upper limit on the number of files that can be created under one directory. The upper limit depends on the length of the file names located in the directory and is approximately 4M to 12M files. If an attempt is made to create a file that exceeds the limit, an error message "No spcae left on device" is output and the file creation fails.

[Advanced Option] File Striping

Home area is provided by the Lustre file system. The Lustre file system distributes and stores file data onto multiple disks. On home area, you can choose two distribution methods which are Round-Robin (default) and Striping.

How to Set Up File Striping

$ lfs setstripe  [options] <dirname | filename>
Option Description
-S Sets a stripe size. -S #k, -S #m or -S #g option sets the size to KiB, MiB or GiB respectively.
-i Specifies the start OST index to which a file is written. If -1 is set, the start OST is randomly selected.
-c Sets a stripe count. If -1 is set, all available OSTs are written.

Tips

To display OST index, use the lfs df or lfs osts command

Example) Set a stripe pattern #1. (Creating a new file with a specific stripe pattern.)

[username@es1 work]$ lfs setstripe -S 1m -i 10 -c 4 stripe-file
[username@es1 work]$ ls
stripe-file

Example) Set a stripe pattern #2. (Setting up a stripe pattern to a directory.)

[username@es1 work]$ mkdir stripe-dir
[username@es1 work]$ lfs setstripe -S 1m -i 10 -c 4 stripe-dir

How to Display File Striping Settings

To display the stripe pattern of a specified file or directory, use the lfs getstripe command.

$ lfs getstripe <dirname | filename>

Example) Display stripe settings #1. (Displaying the stripe pattern of a file.)

[username@es1 work]$ lfs getstripe stripe-file
stripe-file
lmm_stripe_count:  4
lmm_stripe_size:   1048576
lmm_pattern:       1
lmm_layout_gen:    0
lmm_stripe_offset: 10
        obdidx           objid           objid           group
            10         3024641       0x2e2701                0
            11         3026034       0x2e2c72                0
            12         3021952       0x2e1c80                0
            13         3019616       0x2e1360                0

Example) Display stripe settings #2. (Displaying the stripe pattern of a directory.)

[username@es1 work]$ lfs getstripe stripe-dir
stripe-dir
stripe_count:  4 stripe_size:   1048576 stripe_offset: 10

4.2. Group Area

Group area is the disk area shared by each interactive and compute node. To use Group area, "Usage Manager" of the group needs to apply "Add group disk" via ABCI User Portal. Regarding how to add group disk, please refer to Disk Addition Request in the ABCI Portal Guide.

4.3. Local Storage

In ABCI System, 1.6 TB NVMe storage is installed into each compute node and 1.8 TB SATA 3.0 storage is installed into each memory intensive node. There are two ways to utilize this storage as follows:

  • Using as a local storage of each compute node (Using as a local storage).
  • Using as a distributed shared file system, which consists of multiple NVMe storages in multiple compute nodes (Using as a BeeOND storage).

The follwing table shows how to utilize local storage by two types of node.

compute node memory intensive node
using as a local storage ok ok
using as a BeeOND storage ok -

4.3.1. Using as a local storage

The NVMe storage can be used as a local storage for each compute node. In this case, user can access to local storage by using environment variables SGE_LOCALDIR. When using this method, you need not to specify any additional options.

Note that the amount of the local storage you can use is determined by "Resource type". For more detail on "Resource type", please refer to Job Executing Resource.

Warning

The file stored under $SGE_LOCALDIR directory is removed when job finished. The required files need to be moved to Home area or Group area in job script using cp command.

4.3.2. Using as a BeeOND storage

The set of NVMe storages of job assigned compute nodes can be used as a distributed shared file system (BeeGFS) on demand. When using on demand BeeGFS (BeeOND), you need to submit job with -l USE_BEEOND=1 option. And you need to specify -l rt_F option in this case, because node must be exclusively allocated to job.

The created distributed shared file system area can be accessed from /beeond.

Example) sample of job script (use_beeond.sh)

#!/bin/bash

#$-l rt_F=2
#$-l USE_BEEOND=1
#$-cwd

echo test1 > /beeond/foo.txt
echo test2 > /beeond/bar.txt
cp -rp /beeond/foo.txt $HOME/test/foo.txt

Example) Submitting a job

[username@es1 ~]$ qsub -g grpname use_beeond.sh

Example) Status after execution of use_beeond.sh

[username@es1 ~]$ ls $HOME/test/
foo.txt    <- The file remain only when it is copied explicitly in script.

Warning

The file stored under /beeond directory is removed when job finished. The required files need to be moved to Home area or Group area in job script using cp command.

[Advanced Option] Configure BeeOND Servers

A BeeOND filesystem partition consists of two kinds of services running on compute nodes: one is storage service which stores files, and the other is metadata service which stores file matadata. Each service runs on compute nodes. We refer to a compute node which runs storage service as a storage server and a compute node which runs metadata service as a metadata server. Users can specify number of storage servers and metadata servers.

The default values for counts of metadata server and storage server are as follows.

Parameter Default
Count of metadata servers 1
Count of storage servers Number of nodes requested by a job

To change the counts, define following environment variables. These environment variables have to be defined at job submission, and changing in job script takes no effect. When counts of servers are less than the number of requested nodes, servers are lexicographically selected by their names from assigned compute nodes.

Environment Variable Description
BEEOND_METADATA_SERVER Count of metadata servers in integer
BEEOND_STORAGE_SERVER Count of storage servers in integer

The following example create a BeeOND partition with two metadata servers and four storage servers. beegfs-df is used to see the configuration.

Example) sample of job script (use_beeond.sh)

#!/bin/bash

#$-l rt_F=8
#$-l USE_BEEOND=1
#$-v BEEOND_METADATA_SERVER=2
#$-v BEEOND_STORAGE_SERVER=4
#$-cwd

beegfs-df -p /beeond

Example output

METADATA SERVERS:
TargetID   Cap. Pool        Total         Free    %      ITotal       IFree    %
========   =========        =====         ====    =      ======       =====    =
       1      normal    1489.7GiB    1322.7GiB  89%      149.0M      149.0M 100%
       2      normal    1489.7GiB    1322.7GiB  89%      149.0M      149.0M 100%

STORAGE TARGETS:
TargetID   Cap. Pool        Total         Free    %      ITotal       IFree    %
========   =========        =====         ====    =      ======       =====    =
       1      normal    1489.7GiB    1322.7GiB  89%      149.0M      149.0M 100%
       2      normal    1489.7GiB    1322.7GiB  89%      149.0M      149.0M 100%
       3      normal    1489.7GiB    1322.7GiB  89%      149.0M      149.0M 100%
       4      normal    1489.7GiB    1322.7GiB  89%      149.0M      149.0M 100%

[Advanced Option] File Striping

Files are split into small chunks and stored in multiple storage servers in a BeeOND partition. Users can change file striping configuration of BeeOND.

The default configuration of the file striping is as follows.

Parameter Default Description
Stripe size 512 KB File chunk size
Stripe count 4 Number of storage servers that store chunks of a file

Users can configure file striping per-file or per-directory using beegfs-ctl command.

The following example sets file striping configuration of /beeond/data directory as 8 stripe count and 4MB stripe size.

Example) sample of job script (use_beeond.sh)

#!/bin/bash

#$-l rt_F=8
#$-l USE_BEEOND=1
#$-cwd

BEEOND_DIR=/beeond/data
mkdir ${BEEOND_DIR}
beegfs-ctl --setpattern --numtargets=8 --chunksize=4M --mount=/beeond ${BEEOND_DIR}
beegfs-ctl --mount=/beeond --getentryinfo ${BEEOND_DIR}

Output example

New chunksize: 4194304
New number of storage targets: 8

EntryID: 0-5D36F5EC-1
Metadata node: gXXXX.abci.local [ID: 1]
Stripe pattern details:
+ Type: RAID0
+ Chunksize: 4M
+ Number of storage targets: desired: 8
+ Storage Pool: 1 (Default)