Azure HPC Cache data ingest - manual copy method
This article gives detailed instructions for manually copying data to a Blob storage container for use with Azure HPC Cache. It uses multi-threaded parallel operations to optimize the copy speed.
To learn more about moving data to Blob storage for your Azure HPC Cache, read Move data to Azure Blob storage.
Simple copy example
You can manually create a multi-threaded copy on a client by running more than one copy command at once in the background against predefined sets of files or paths.
The Linux/UNIX cp command includes the argument -p to preserve ownership and mtime metadata. Adding this argument to the commands below is optional. (Adding the argument increases the number of file system calls sent from the client to the destination file system for metadata modification.)
This simple example copies two files in parallel:
cp /mnt/source/file1 /mnt/destination1/ & cp /mnt/source/file2 /mnt/destination1/ &
After issuing this command, the jobs command will show that two threads are running.
Copy data with predictable file names
If your file names are predictable, you can use expressions to create parallel copy threads.
For example, if your directory contains 1000 files that are numbered sequentially from 0001 to 1000, you can use the following expressions to create 10 parallel threads that each copy 100 files:
cp /mnt/source/file0* /mnt/destination1/ & \
cp /mnt/source/file1* /mnt/destination1/ & \
cp /mnt/source/file2* /mnt/destination1/ & \
cp /mnt/source/file3* /mnt/destination1/ & \
cp /mnt/source/file4* /mnt/destination1/ & \
cp /mnt/source/file5* /mnt/destination1/ & \
cp /mnt/source/file6* /mnt/destination1/ & \
cp /mnt/source/file7* /mnt/destination1/ & \
cp /mnt/source/file8* /mnt/destination1/ & \
cp /mnt/source/file9* /mnt/destination1/
Copy data with unstructured file names
If your file naming structure is not predictable, you can group files by directory names.
This example collects entire directories to send to cp commands run as background tasks:
/root
|-/dir1
| |-/dir1a
| |-/dir1b
| |-/dir1c
|-/dir1c1
|-/dir1d
After the files are collected, you can run parallel copy commands to recursively copy the subdirectories and all of their contents:
cp /mnt/source/* /mnt/destination/
mkdir -p /mnt/destination/dir1 && cp /mnt/source/dir1/* mnt/destination/dir1/ &
cp -R /mnt/source/dir1/dir1a /mnt/destination/dir1/ &
cp -R /mnt/source/dir1/dir1b /mnt/destination/dir1/ &
cp -R /mnt/source/dir1/dir1c /mnt/destination/dir1/ & # this command copies dir1c1 via recursion
cp -R /mnt/source/dir1/dir1d /mnt/destination/dir1/ &
When to add mount points
After you have enough parallel threads going against a single destination file system mount point, there will be a point where adding more threads does not give more throughput. (Throughput will be measured in files/second or bytes/second, depending on your type of data.) Or worse, over-threading can sometimes cause a throughput degradation.
When this happens, you can add client-side mount points to other Azure HPC Cache mount addresses, using the same remote file system mount path:
10.1.0.100:/nfs on /mnt/sourcetype nfs (rw,vers=3,proto=tcp,addr=10.1.0.100)
10.1.1.101:/nfs on /mnt/destination1type nfs (rw,vers=3,proto=tcp,addr=10.1.1.101)
10.1.1.102:/nfs on /mnt/destination2type nfs (rw,vers=3,proto=tcp,addr=10.1.1.102)
10.1.1.103:/nfs on /mnt/destination3type nfs (rw,vers=3,proto=tcp,addr=10.1.1.103)
Adding client-side mount points lets you fork off additional copy commands to the additional /mnt/destination[1-3] mount points, achieving further parallelism.
For example, if your files are very large, you might define the copy commands to use distinct destination paths, sending out more commands in parallel from the client performing the copy.
cp /mnt/source/file0* /mnt/destination1/ & \
cp /mnt/source/file1* /mnt/destination2/ & \
cp /mnt/source/file2* /mnt/destination3/ & \
cp /mnt/source/file3* /mnt/destination1/ & \
cp /mnt/source/file4* /mnt/destination2/ & \
cp /mnt/source/file5* /mnt/destination3/ & \
cp /mnt/source/file6* /mnt/destination1/ & \
cp /mnt/source/file7* /mnt/destination2/ & \
cp /mnt/source/file8* /mnt/destination3/ & \
In the example above, all three destination mount points are being targeted by the client file copy processes.
When to add clients
Lastly, when you have reached the client's capabilities, adding more copy threads or additional mount points will not yield any additional files/sec or bytes/sec increases. In that situation, you can deploy another client with the same set of mount points that will be running its own sets of file copy processes.
Example:
Client1: cp -R /mnt/source/dir1/dir1a /mnt/destination/dir1/ &
Client1: cp -R /mnt/source/dir2/dir2a /mnt/destination/dir2/ &
Client1: cp -R /mnt/source/dir3/dir3a /mnt/destination/dir3/ &
Client2: cp -R /mnt/source/dir1/dir1b /mnt/destination/dir1/ &
Client2: cp -R /mnt/source/dir2/dir2b /mnt/destination/dir2/ &
Client2: cp -R /mnt/source/dir3/dir3b /mnt/destination/dir3/ &
Client3: cp -R /mnt/source/dir1/dir1c /mnt/destination/dir1/ &
Client3: cp -R /mnt/source/dir2/dir2c /mnt/destination/dir2/ &
Client3: cp -R /mnt/source/dir3/dir3c /mnt/destination/dir3/ &
Client4: cp -R /mnt/source/dir1/dir1d /mnt/destination/dir1/ &
Client4: cp -R /mnt/source/dir2/dir2d /mnt/destination/dir2/ &
Client4: cp -R /mnt/source/dir3/dir3d /mnt/destination/dir3/ &
Create file manifests
After understanding the approaches above (multiple copy-threads per destination, multiple destinations per client, multiple clients per network-accessible source file system), consider this recommendation: Build file manifests and then use them with copy commands across multiple clients.
This scenario uses the UNIX find command to create manifests of files or directories:
user@build:/mnt/source > find . -mindepth 4 -maxdepth 4 -type d
./atj5b55c53be6-01/support/gsi/2018-07-22T21:12:06EDT
./atj5b55c53be6-01/support/pcap/2018-07-23T01:34:57UTC
./atj5b55c53be6-01/support/trace/rolling
./atj5b55c53be6-03/support/gsi/2018-07-22T21:12:06EDT
./atj5b55c53be6-03/support/pcap/2018-07-23T01:34:57UTC
./atj5b55c53be6-03/support/trace/rolling
./atj5b55c53be6-02/support/gsi/2018-07-22T21:12:06EDT
./atj5b55c53be6-02/support/pcap/2018-07-23T01:34:57UTC
./atj5b55c53be6-02/support/trace/rolling
Redirect this result to a file: find . -mindepth 4 -maxdepth 4 -type d > /tmp/foo
Then you can iterate through the manifest, using BASH commands to count files and determine the sizes of the subdirectories:
ben@xlcycl1:/sps/internal/atj5b5ab44b7f > for i in $(cat /tmp/foo); do echo " `find ${i} |wc -l` `du -sh ${i}`"; done
244 3.5M ./atj5b5ab44b7f-02/support/gsi/2018-07-18T00:07:03EDT
9 172K ./atj5b5ab44b7f-02/support/gsi/stats_2018-07-18T05:01:00UTC
124 5.8M ./atj5b5ab44b7f-02/support/gsi/stats_2018-07-19T01:01:01UTC
152 15M ./atj5b5ab44b7f-02/support/gsi/stats_2018-07-20T01:01:00UTC
131 13M ./atj5b5ab44b7f-02/support/gsi/stats_2018-07-20T21:59:41UTC_partial
789 6.2M ./atj5b5ab44b7f-02/support/gsi/2018-07-20T21:59:41UTC
134 12M ./atj5b5ab44b7f-02/support/gsi/stats_2018-07-20T22:22:55UTC_hpccache_catchup
7 16K ./atj5b5ab44b7f-02/support/pcap/2018-07-18T17:12:19UTC
8 83K ./atj5b5ab44b7f-02/support/pcap/2018-07-18T17:17:17UTC
575 7.7M ./atj5b5ab44b7f-02/support/cores/armada_main.2000.1531980253.gsi
33 4.4G ./atj5b5ab44b7f-02/support/trace/rolling
281 6.6M ./atj5b5ab44b7f-01/support/gsi/2018-07-18T00:07:03EDT
15 182K ./atj5b5ab44b7f-01/support/gsi/stats_2018-07-18T05:01:00UTC
244 17M ./atj5b5ab44b7f-01/support/gsi/stats_2018-07-19T01:01:01UTC
299 31M ./atj5b5ab44b7f-01/support/gsi/stats_2018-07-20T01:01:00UTC
256 29M ./atj5b5ab44b7f-01/support/gsi/stats_2018-07-20T21:59:41UTC_partial
889 7.7M ./atj5b5ab44b7f-01/support/gsi/2018-07-20T21:59:41UTC
262 29M ./atj5b5ab44b7f-01/support/gsi/stats_2018-07-20T22:22:55UTC_hpccache_catchup
11 248K ./atj5b5ab44b7f-01/support/pcap/2018-07-18T17:12:19UTC
11 88K ./atj5b5ab44b7f-01/support/pcap/2018-07-18T17:17:17UTC
645 11M ./atj5b5ab44b7f-01/support/cores/armada_main.2019.1531980253.gsi
33 4.0G ./atj5b5ab44b7f-01/support/trace/rolling
244 2.1M ./atj5b5ab44b7f-03/support/gsi/2018-07-18T00:07:03EDT
9 158K ./atj5b5ab44b7f-03/support/gsi/stats_2018-07-18T05:01:00UTC
124 5.3M ./atj5b5ab44b7f-03/support/gsi/stats_2018-07-19T01:01:01UTC
152 15M ./atj5b5ab44b7f-03/support/gsi/stats_2018-07-20T01:01:00UTC
131 12M ./atj5b5ab44b7f-03/support/gsi/stats_2018-07-20T21:59:41UTC_partial
789 8.4M ./atj5b5ab44b7f-03/support/gsi/2018-07-20T21:59:41UTC
134 14M ./atj5b5ab44b7f-03/support/gsi/stats_2018-07-20T22:25:58UTC_hpccache_catchup
7 159K ./atj5b5ab44b7f-03/support/pcap/2018-07-18T17:12:19UTC
7 157K ./atj5b5ab44b7f-03/support/pcap/2018-07-18T17:17:17UTC
576 12M ./atj5b5ab44b7f-03/support/cores/armada_main.2013.1531980253.gsi
33 2.8G ./atj5b5ab44b7f-03/support/trace/rolling
Lastly, you must craft the actual file copy commands to the clients.
If you have four clients, use this command:
for i in 1 2 3 4 ; do sed -n ${i}~4p /tmp/foo > /tmp/client${i}; done
If you have five clients, use something like this:
for i in 1 2 3 4 5; do sed -n ${i}~5p /tmp/foo > /tmp/client${i}; done
And for six.... Extrapolate as needed.
for i in 1 2 3 4 5 6; do sed -n ${i}~6p /tmp/foo > /tmp/client${i}; done
You will get N resulting files, one for each of your N clients that has the path names to the level-four directories obtained as part of the output from the find command.
Use each file to build the copy command:
for i in 1 2 3 4 5 6; do for j in $(cat /tmp/client${i}); do echo "cp -p -R /mnt/source/${j} /mnt/destination/${j}" >> /tmp/client${i}_copy_commands ; done; done
The above will give you N files, each with a copy command per line, that can be run as a BASH script on the client.
The goal is to run multiple threads of these scripts concurrently per client in parallel on multiple clients.
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