Storage Space Write Speed Drop to 0

Question

I have a HCI with 4 Node (4x800GB SSD and 12x8TB HDD per node) as attached.
I have 2 virtual disks with 1 virtual disk attached to Cluster File Server Role.
When I copy large file (50GB) from client to FileServer the speed is fast for first 5GB.
After 5GB, the speed drop to zero. I have check Storage Space Write Cache in Window Admin Center and ther Disk Used % up to 99.9%.
The speed down for around 90s and up again for next 5GB and down again.

Please help me to fix this issue.
Many thanks.

Answer 1

Hello

Thank you for your question and reaching out.

There can be many reason of slow copying,

1. Please try to RSS or TCP offload or Jumbo Frames on NIC
2. Disable any Antivirus program or Windows firewall you may have for temporary purpose.

3.File copies sometimes start fast and then slow down. Follow these guidelines to verify this situation:

This usually occurs when the initial copy is cached or buffered (either in memory or in the RAID controller's memory cache) and the cache runs out. This forces data to be written directly to disk (write-through). This is a slower process.

Use storage performance monitor counters to determine whether storage performance degrades over time

4. Use RAMMap (SysInternals) to determine whether "Mapped File" usage in memory stops growing because of free memory exhaustion.

Reference :

https://learn.microsoft.com/en-us/windows-server/storage/file-server/troubleshoot/slow-file-transfer

https://learn.microsoft.com/en-us/troubleshoot/windows-client/performance/troubleshooting-slow-file-copying-in-windows

https://techcommunity.microsoft.com/t5/storage-at-microsoft/the-mystery-of-the-slow-file-copy-from-the-fast-computer/ba-p/2637581

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