PowerScale: Isilon: Small file transfers are slow over SMB

You may notice that transferring many small files over SMB is significantly slower than transfer of large files.
This can affect workflows that are reliant on many small file transfers.

It is expected that the throughput of transferring lots of small files is much slower than transfer of large files.
This is because the SMB overhead-to-data-payload ratio is worse when transferring many small files.

Transferring files over SMB requires create request and other SMB and file system calls for each file being transferred, thereafter the payload will also get transferred.
The "overhead" in this scenario is all the SMB protocol-related calls and there will be many more of these when transferring a high amount small files, compared to a few large files.
That makes small file transfers significantly less efficient (thus lower throughput) compared to large file transfers.

Both reads and writes suffer from the same issue.

This is expected and normal behavior due to the above reasons. Microsoft (creators and owners of the SMB protocol) has also made a statement about the same, which is worth a read:
https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/slow-smb-file-transfer#slow-transfer-of-small-files

There is not much you can do about it, other than adjust the workflow. It is not an Isilon limitation but more a limitation within the SMB protocol.
If the workflow relies heavily on small file transfer, then it should be considered whether, for example, NFS can be used instead as that should be more efficient for small file transfers.
Testing against the workflow should be performed to find the best suitable protocol. 

Generally speaking, if you see good SMB transfer speeds with large files and poor speeds with many small files, this article likely matches your issue.
This is not something that you can change Isilon side and thus the Dell account team can step in to help review the workflow for the most efficient setup.