Examples for using Allas in CSC supercomputers

CSC supercomputers, Puhti and Mahti, do not provide permanent storage space for research data. Data that needs to be stored for a longer time than just a few weeks should be copied to Allas object storage service. Allas provides a platform that you can use to store your data as long as your CSC project is active. In addition to storage, Allas can be used for transporting data between different servers and sharing data with other users.

• Allas user guide

This tutorial provides four examples for using Allas on Puhti and Mahti. The examples are based on interactively executed commands, and thus apply only for relatively small datasets (max. some hundreds of GBs).

1. The first example uses the a-commands (a-put, a-get) for uploading data from Mahti to Allas, and then downloading the data to Puhti.
2. The second example transfers the same data using Rclone.
3. The third example focuses on uploading large files to Allas.
4. The fourth example handles the case in which the dataset to be copied includes a large amount of files.

The a-commands are better suited for cases where the data is mainly used within the CSC computing environment (Puhti, Mahti). The second option, Rclone, is good for cases when the data will be used outside CSC too.

Getting access to Allas

By default, CSC computing projects do not have access to Allas. Thus, the first thing is to add the Allas service to your project. This is done in the MyCSC portal. Note that only the project manager can apply for access.

The default storage quota in Allas is 10 TB. As this space is shared with all project members, it is possible that the space is not sufficient. In that case, you should estimate how much space is needed and request more space. The request should be sent to CSC Service Desk. Please include in your quota request:

1. The ID/name of your project
2. The amount of Allas space needed
3. A short description of the data to be stored

Note that the data stored in Allas consume billing units of the project.

Example 1: Using Allas with a-commands

A. Uploading data from Mahti to Allas

The a-commands are Allas-specific tools that allow an easy start with Allas. The a-commands archive and move data automatically. You can also compress your data before storage. For example, for text-formatted data compression reduces the storage space needed, but on the other hand makes the transfer process slightly slower. The a-commands are a good option for miscellaneous data that is mostly used in the CSC environment.

In this example, we have a subdirectory genomes/zebrafish in the scratch directory of a project in Mahti (/scratch/project_2001659). The zebrafish directory contains eight files listed below:

[kkayttaj@mahti-login11 ~]$ ls /scratch/project_2001659/genomes/zebrafish
Danio_rerio.GRCz10.91.1.bt2      Danio_rerio.GRCz10.91.2.bt2  
Danio_rerio.GRCz10.91.3.bt2      Danio_rerio.GRCz10.91.4.bt2  
Danio_rerio.GRCz10.91.rev.1.bt2  Danio_rerio.GRCz10.91.rev.2.bt2  
Danio_rerio.GRCz10.fa            Danio_rerio.GRCz10.fa.fai

To copy the content of this directory to Allas, we first set up the Allas environment:

module load allas

Then, we open a connection to Allas using the command allas-conf. The command asks for the user's CSC password and then lists the Allas projects that are accessible. In this case, we select project_2001659.

[kkayttaj@mahti-login11 ~]$ allas-conf
Mode swift
Please enter CSC password for account kkayttaj: <password>
Checking projects available for your account.
Please wait.
1) project_2000982     2) project_2001659     3) project_2000136      4) abort allas_conf
Please choose a project by giving an item number from the list above: 2
Configuration will be done for project: project_2001659
Protocols:
  swift
Connection stays active for eight hours.

allas-conf opens a connection to the specified Allas project for eight hours. If we want to start using another project, we need to run allas-conf again. However, in a single shell session allas-conf enables only one Allas project to be active at a time. Note that certain tools, for example rclone, can nonetheless be set up to use several Allas projects at the same time.

Next, we enter the zebrafish directory:

cd /scratch/project_2001659/genomes/zebrafish

We can now upload files one by one to Allas using the a-put command:

a-put Danio_rerio.GRCz10.fa

At the end of the upload process, the command reports:

-------------------------------------------------------------------------------
1 files from Danio_rerio.GRCz10.fa uploaded to bucket 2001659-mahti-SCRATCH in Allas as one file: 
2001659-mahti-SCRATCH/genomes/zebrafish/Danio_rerio.GRCz10.fa
-----------------------------------------------------------------

Upload summary:
              Date                      Name  Files Size(kB)         Location in allas
 12.10.20 12:10:50     Danio_rerio.GRCz10.fa      1  1330852 2001659-mahti-SCRATCH/genomes/zebrafish
-----------------------------------------------------------------
OK

Moving data to Allas file by file is slow and produces a large amount of objects. It is often more efficient to upload data to Allas one directory at a time and store the data in bigger chunks. For example, to upload the zebrafish directory, we first enter the parent directory genomes:

cd /scratch/project_2001659/genomes/

Then, we use a-put to upload the whole zebrafish directory to Allas as a single object:

a-put zebrafish/

At the end of the upload process, the command reports:

-------------------------------------------------------------------------------
8 files from zebrafish uploaded to bucket 2001659-mahti-SCRATCH in Allas as one tar file: 
2001659-mahti-SCRATCH/genomes/zebrafish.tar
-----------------------------------------------------------------

Upload summary:
              Date                      Name  Files Size(kB)         Location in allas
 12.10.20 14:10:47                 zebrafish      8  3191656 2001659-mahti-SCRATCH/genomes
-----------------------------------------------------------------
OK

After this, we have another object in the 2001659-mahti-SCRATCH bucket:

[kkayttaj@mahti-login11 genomes]$ a-list 2001659-mahti-SCRATCH
2001659-mahti-SCRATCH/genomes/zebrafish.tar
2001659-mahti-SCRATCH/genomes/zebrafish/Danio_rerio.GRCz10.fa

Note that the file Danio_rerio.GRCz10.fa is in fact now stored in Allas twice; both as an individual object (genomes/zebrafish/Danio_rerio.GRCz10.fa) and as part of the genomes/zebrafish.tar object.

B. Downloading to Puhti

Next, we download the same data to Puhti. After connecting to Puhti, we go to the scratch directory of project 2001659 and load the allas module:

cd /scratch/project_2001659
module load allas

In this case, we want to use Allas with the project project_2001659, so we can give the project name as an argument for the allas-conf command:

allas-conf project_2001659

Now the configuration process asks only for the CSC password and then sets up the connection to Allas for project 2001659. As the Puhti scratch directory is shared by all project members, we create a user-specific subdirectory kkayttaj:

mkdir -p kkayttaj
cd kkayttaj/

With the command a-list, we can now see the objects that were just uploaded from Mahti to Allas:

[kkayttaj@puhti-login12 kkayttaj]$ a-list
2001659-mahti-SCRATCH
[kkayttaj@puhti-login12 kkayttaj]$ a-list 2001659-mahti-SCRATCH
2001659-mahti-SCRATCH/genomes/zebrafish.tar
2001659-mahti-SCRATCH/genomes/zebrafish/Danio_rerio.GRCz10.fa

Locating data is easy as there are only two objects in the bucket, but as more data is added to Allas, locating a specific file among dozens of buckets containing hundreds of objects may be difficult. In that case, you can search for a specific file using the command a-find. In this example, we can check if an object contains the file Danio_rerio.GRCz10.fa:

[kkayttaj@puhti-login12 kkayttaj]$ a-find -a Danio_rerio.GRCz10.fa
----------------------------------------------
Checking bucket: 2001659-mahti-SCRATCH
Object: 2001659-mahti-SCRATCH/genomes/zebrafish.tar 
includes 2 file names that that match query: Danio_rerio.GRCz10.fa
Object: 2001659-mahti-SCRATCH/genomes/zebrafish/Danio_rerio.GRCz10.fa
includes 1 file names that that match query: Danio_rerio.GRCz10.fa
------------------------------------------------ 
Query: Danio_rerio.GRCz10.fa
Total of 3 hits were found in 2 objects
-------------------------------------------------

The a-find report above tells, for example, that the object 2001659-mahti-SCRATCH/genomes/zebrafish.tar contains two files whose names match Danio_rerio.GRCz10.fa (the other file is Danio_rerio.GRCz10.fa.fai). Note that a-find finds matches only among objects that were uploaded with a-put.

Next, we download the data to Puhti using the a-get command:

[kkayttaj@puhti-login12 kkayttaj]$ a-get 2001659-mahti-SCRATCH/genomes/zebrafish.tar
Starting to copy data from allas...
Object:
  2001659-mahti-SCRATCH/genomes/zebrafish.tar
copied and uncompressed from allas into:
  zebrafish

After this, the current working directory in Puhti has a new directory zebrafish that contains the files that were previously uploaded from Mahti to Allas:

[kkayttaj@puhti-login12 kkayttaj]$ ls zebrafish/
Danio_rerio.GRCz10.91.1.bt2      Danio_rerio.GRCz10.91.3.bt2  
Danio_rerio.GRCz10.91.2.bt2      Danio_rerio.GRCz10.91.4.bt2
Danio_rerio.GRCz10.91.rev.1.bt2  Danio_rerio.GRCz10.fa
Danio_rerio.GRCz10.91.rev.2.bt2  Danio_rerio.GRCz10.fa.fai

Example 2: Using Allas with Rclone

A. Uploading data with Rclone

Rclone is the power-user tool for Allas. It is good in cases where the data must be stored such that each file is a separate object.

Warning

Rclone provides a fast and efficient way to use Allas, but you should use it carefully as Rclone operations can overwrite and remove data both in Allas and in the local disk environment without notifying or asking for confirmation.

• Using Allas with Rclone from Puhti and Mahti

This example uses the same data as the previous case: in the scratch directory of Mahti, we have a subdirectory genomes/zebrafish that contains the eight files listed below:

[kkayttaj@mahti-login11 ~]$ ls /scratch/project_2001659/genomes/zebrafish
Danio_rerio.GRCz10.91.1.bt2      Danio_rerio.GRCz10.91.2.bt2  
Danio_rerio.GRCz10.91.3.bt2      Danio_rerio.GRCz10.91.4.bt2  
Danio_rerio.GRCz10.91.rev.1.bt2  Danio_rerio.GRCz10.91.rev.2.bt2  
Danio_rerio.GRCz10.fa            Danio_rerio.GRCz10.fa.fai

To copy the content of this directory to Allas, we first set up the Allas environment:

module load allas

Then, we open a connection to Allas using the command allas-conf. The command asks for the user's CSC password and then lists the Allas projects that the user can access. In this case, we select project_2001659:

[kkayttaj@mahti-login11 ~]$ allas-conf
Please enter CSC password for account kkayttaj: <password>
Checking projects available for your account.
Please wait.
1) project_2000982     2) project_2001659     3) project_2000136      4) abort allas_conf
Please choose a project by giving an item number from the list above: 2
Configuration will be done for project: project_2001659
Protocols:
  swift
Connection stays active for eight hours.

The allas-conf procedure above defines an Allas connection that is valid for eight hours. Next, we go to the genomes directory:

cd /scratch/project_2001659/genomes

Instead of a-put that was used in the previous example, we use command rclone copyto to copy all files from the given directory to Allas. In the case of rclone, there is no default bucket. Instead, we have to define a bucket. In this example, we use the bucket name 2001659-genomes and define each object name to have the prefix zebrafish.

rclone copyto zebrafish/ allas:2001659-genomes/zebrafish

After copying the files, we can use rclone ls to see what has been uploaded to Allas:

[kkayttaj@mahti-login11 genomes] rclone ls allas:2001659-genomes/zebrafish
450646234 Danio_rerio.GRCz10.91.1.bt2
334651392 Danio_rerio.GRCz10.91.2.bt2
   187325 Danio_rerio.GRCz10.91.3.bt2
334651387 Danio_rerio.GRCz10.91.4.bt2
450646234 Danio_rerio.GRCz10.91.rev.1.bt2
334651392 Danio_rerio.GRCz10.91.rev.2.bt2
1362788082 Danio_rerio.GRCz10.fa
      715 Danio_rerio.GRCz10.fa.fai

B. Downloading the data to Puhti

Next, we download the same data to Puhti. After connecting to Puhti, we go to the scratch directory of project_2001659 and load the allas module:

cd /scratch/project_2001659
module load allas

In this case, we want to use Allas with the project 2001659, so we can give the project name as an argument for the allas-conf command:

allas-conf project_2001659

Now the configuration process asks only for the CSC password and then sets up the connection to Allas for project 2001659. As the Puhti scratch directory is shared by all project members, we create a user-specific subdirectory kkayttaj and go there:

mkdir -p kkayttaj
cd kkayttaj/

We can now use the command rclone lsd to check the available buckets in Allas:

[kkayttaj@puhti-login12 kkayttaj]$ rclone lsd allas:
  3268222761 2020-10-03 10:01:42         8 2001659-genomes
  2576778428 2020-10-03 10:01:42         4 2001659-mahti-SCRATCH

Now we see two buckets. 2001659-genomes is the one that was just created in this example, while 2001659-mahti-SCRATCH originates from the previous a-command example. Next, we list the objects in the 2001659-genomes bucket:

[kkayttaj@puhti-login12 kkayttaj]$ rclone ls allas:2001659-genomes
450646234 zebrafish/Danio_rerio.GRCz10.91.1.bt2
334651392 zebrafish/Danio_rerio.GRCz10.91.2.bt2
   187325 zebrafish/Danio_rerio.GRCz10.91.3.bt2
334651387 zebrafish/Danio_rerio.GRCz10.91.4.bt2
450646234 zebrafish/Danio_rerio.GRCz10.91.rev.1.bt2
334651392 zebrafish/Danio_rerio.GRCz10.91.rev.2.bt2
1362788082 zebrafish/Danio_rerio.GRCz10.fa
      715 zebrafish/Danio_rerio.GRCz10.fa.fa

Finally, we use the rclone copyto command to copy the data from Allas to Puhti into a new directory zebrafish2:

[kkayttaj@puhti-login12 kkayttaj]$ rclone -P copyto allas:2001659-genomes/zebrafish zebrafish2
Transferred:        3.044 GiB / 3.044 GiB, 100%, 323.600 MBytes/s, ETA 0s
Transferred:            8 / 8, 100%
Elapsed time:        9.6s

[kkayttaj@puhti-login12 kkayttaj]$ ls zebrafish2
Danio_rerio.GRCz10.91.1.bt2      Danio_rerio.GRCz10.91.3.bt2  
Danio_rerio.GRCz10.91.2.bt2      Danio_rerio.GRCz10.91.4.bt2
Danio_rerio.GRCz10.91.rev.1.bt2  Danio_rerio.GRCz10.fa
Danio_rerio.GRCz10.91.rev.2.bt2  Danio_rerio.GRCz10.fa.fai

Example 3: Uploading large files to Allas

In the previous two examples, the actual amount of data was rather moderate, only a few gigabytes. If the size of an individual data file is hundreds of gigabytes or more, transporting only a few files may take longer than the duration of the token-based Allas authentication.

In this example, we use a-put to upload a set of large files from Mahti to Allas.

The first thing to do is to open a Mahti connection that can remain running for a long time. In this example, we use screen command to open a session that can be left running in the background:

ssh <username>@mahti.csc.fi
screen

The screen command starts a virtual session on the login node of Mahti. You can leave this virtual screen session running in the background and log out from Mahti, but you should check which login node (mahti-login[11,12,14,15]) your session is running on because you need to log in to the same node to reconnect to your screen session later on.

In the screen session, first load the allas module and use allas-conf to establish a connection to Allas.

module load allas
allas-conf -k

Here, allas-conf is used with the option -k that saves your CSC password in an environment variable ($OS_PASSWORD) so that the connection to Allas can later be automatically reconfigured without needing to give the password again.

After opening the Allas connection, we move to a directory my_data where we have three subdirectories (50, 90, 100). We list the gzip-compressed files in these directories:

[kkayttaj@mahti-login11 ~] cd /scratch/project_2001659/my_data
[kkayttaj@mahti-login my_data] ls -lh */*.gz
-rw-rwxr-x 1 kkayttaj csc  45G May  8 12:57 100/uniref100.fasta.gz
-rw-rwxr-x 1 kkayttaj csc  61G Jun  5 13:09 100/uniref100.xml.gz
-rw-rwxr-x 1 kkayttaj csc 589M Jun  5 13:09 50/uniref50.fasta.gz
-rw-rwxr-x 1 kkayttaj csc  17G Jun  5 13:09 50/uniref50.xml.gz
-rw-r-xr-x 1 kkayttaj csc 4.2G Jul  6 09:46 90/uniref90.fasta.gz
-rw-rwxr-x 1 kkayttaj csc  33G Jun  5 13:09 90/uniref90.xml.gz

Next, we launch the upload process. In this case, we do not use the default bucket name, but assign the name to be 2001659-uniref:

a-put -b 2001659-uniref */*.gz

This command uploads the files listed above to Allas. Alternatively, we could launch the same upload with rclone copy:

for f in */*.gz
do
    rclone copy $f allas:2001659-uniref
done

We can leave the session running in the background by pressing Ctrl-A D. Now, we can log out from Mahti with the screen session remaining active in the Mahti login node we used (in this case, mahti-login11).

To re-connect to this session, we first connect to the Mahti node where the screen session is running:

ssh <username>@mahti-login11.csc.fi

Then, we reattach the screen session:

screen -r

Once the a-put command is finished, we will run a-check command to check if all the data objects have been created. a-check needs to be executed with the exact same options that were used with the a-put command. So in this case the command would be:

a-check -b 2001659-uniref */*.gz

The a-check command compares the item names to be uploaded to the matching objects in Allas. The files or directories that don't have a target object in Allas are reported and stored in a file. In this case, if some objects in the a-put command above would be missing, then a-check would list the missing files and directories in a file missing_2001659-uniref_63449 (the number at the end is just a random number).

The file of missing items can then be used with a-put option --input-list to continue the failed upload process:

a-put -b 2001659-uniref --nc --input-list missing_2001659-uniref_63449

You should note that a-check does not check if the actual contents of the object is correct. It checks only the object names, which might as well originate from some other sources.

Example 4: Uploading complex directory structures to Allas

Some workflows and software create complex directory structures to store and manage data. You might have directories that have thousands or even millions of individual files. Copying such datasets to Allas takes time and is not always straightforward. The most reasonable way to upload this kind of data depends on the case. This example introduces a few alternatives.

First, we open a screen session on Puhti and set up an Allas connection just like in the previous example:

ssh <username>@puhti.csc.fi
screen
module load allas
allas-conf -k

Suppose we have a directory structure that contains images from road condition cameras from ten locations with an interval of ten minutes from the years 2014–2018. The data is located in the directory road_cameras where each location has its own subdirectory (ten directories). Inside each subdirectory, there is another layer of subdirectories, one for each year (five subdirectories), each containing subdirectories for every day of the year (further 365 subdirectories), each containing 144 small image files.

For example:

road_cameras/site_7/2017/day211/image_654887.jpg

Thus, the total number of files in the road_cameras directory is 10 * 5 * 365 * 144 = 2 628 000.

In principle, we could copy all 2.6 million files as separate objects to Allas, but in that case, we should split the data into multiple buckets as one bucket can have at most 0.5 million objects. You could, for example, run a separate rclone command for each site_* directory and put the data from each site to a site-specific bucket. For example:

rclone copyto road_cameras/site_1 allas:2001659_road_cameras_site_1/

This way, you would end up creating ten buckets each containing 262 800 objects. This approach could be the most efficient way for storing and reusing the data if you know that you will need to access individual images randomly.

As another extreme option, we could use a-put and collect all data into a single archive object. In order to do that, you must add the option --skip-filelist to the a-put command. By default, a-put collects detailed metadata of each file in an ameta file. However, if you have millions of files, collecting this information takes a long time. If you need to know the file names, you can use the --simple-fileslist option to collect the names – but no other information – of the files in the metadata file. This already speeds up the preprocessing significantly. However, as in this case the naming has been systematic, storing the file names to the metadata files can be just ignored altogether (--skip-filelist), which is the fastest option.

a-put --skip-filelist road_cameras/

This approach would store all 2,6 million files as a single object.

In practice, however, the optimal way of storing the data is often something between these two extremes. As a compromise, you could apply packing at a higher level in the hierarchy. For example:

a-put --skip-filelist road_cameras/site_*

This would produce ten objects, each containing all information from a single camera site. Alternatively, you could do the archiving so that data from each year from each camera is collected as a single object:

a-put --skip-filelist road_cameras/site_*/20*

This option would store the data as 50 objects. Day-based objects for each camera might be the most practical option for using the data later on, but as a downside, preprocessing the data into 10 * 5 * 365 = 18250 objects probably takes quite a long time.

Copying millions of files to Allas takes a long time regardless of the method. If we have started the a-put command inside a screen session, we can detach from the virtual session by pressing Ctrl-A D, log out from Puhti and leave the upload process running for days.

Once the a-put command is finished, we will run a-check command to check if all the data objects have been created. a-check needs to be executed with the exact same options that were used with the a-put command. So in this case the command would be:

a-check --skip-filelist road_cameras/site_*/20*

The a-check command compares the item names to be uploaded to the matching objects in Allas. The files or directories that don't have a target object in Allas are reported and stored in a file. In this case, if some objects in the a-put command above would be missing, then a-check would list the missing files and directories in a file missing_<bucket_name>_<number> (the number at the end is just a random number).

The file of missing items can then be used with a-put option --input-list to continue the failed upload process:

a-put -b 2001659-uniref --nc --input-list missing_<bucket_name>_<number>

You should note that a-check does not check if the actual contents of the object is correct. It checks only the object names, which might as well originate from some other sources.

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