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+--- Thread: Data transfer between 2 x 1821+ (/showthread.php?tid=11627)
Data transfer between 2 x 1821+ - Enquiries - 01-15-2025
My PC and 2 x 1821+ are equipt with 10Gbit adapters via a unmagable 10Gbit switch.
Data transfer from pc to Nas 1 or NAS 2 is about 900MB/s that is what is shoul be.
But transferring between the 2 nasses or from the nasses to pc is about 250MB/s.
I checked many videos about optimal settings in DSM but still nothing helps.
What could possible be the case?
Nas 1 is with 6 x 16 TB in SHR2
Nas 2 is with 2 x 16TB, 2 x 8 TB and 4 x 4TB in SHR1
RE: Data transfer between 2 x 1821+ - ed - 01-17-2025
Thank you for your message. It’s great to see your setup using 10GbE networking, but it’s clear something isn’t performing as expected with NAS-to-NAS or NAS-to-PC transfers. Let’s break down potential causes and solutions:
Potential Causes of Slow NAS-to-NAS Transfers
Disk Throughput Limitations:
Your NAS 1 (SHR2) and NAS 2 (SHR1) have different RAID levels and drive combinations. SHR2 on NAS 1 uses double parity, which can reduce write performance compared to SHR1 on NAS 2.
NAS 2 has mixed drive sizes and capacities, which can impact the performance of SHR1, especially if larger drives are slower models.
Protocol Overhead:
If you're transferring via SMB (default file-sharing protocol), there may be additional overhead compared to PC-to-NAS transfers. This is especially noticeable in NAS-to-NAS transfers where protocol inefficiencies can cause bottlenecks.
CPU Utilization on the NAS Devices:
The DS1821+ uses an AMD Ryzen V1500B CPU, which is efficient but can become a bottleneck during intensive transfers, especially when SHR and encryption are involved.
Switch Configuration:
While your 10GbE switch is unmanaged, some devices can experience suboptimal routing or packet loss without proper flow control or jumbo frame support.
Steps to Troubleshoot and Optimize
Check Disk Performance:
Run a RAID Benchmark in DSM on both NAS devices to assess read and write speeds.
Verify the health of all drives to ensure none are underperforming due to errors or age.
Optimize Network Settings:
Enable Jumbo Frames (MTU 9000) on all devices (NAS 1, NAS 2, PC, and switch if supported).
Use the same MTU size across the entire network.
NAS-to-NAS Transfers:
Use Hyper Backup or Synology Drive ShareSync for efficient NAS-to-NAS transfers. These tools optimize performance by reducing protocol overhead.
Test direct transfers via rsync or SCP using SSH to compare speeds.
SMB Configuration:
In DSM, go to File Services > SMB > Advanced Settings and:
Enable Transport Encryption Mode: Minimum (for testing).
Set SMB3 Multichannel to "enabled" for faster performance on multi-threaded transfers.
Check CPU Usage:
During transfers, monitor the CPU and memory usage on both NAS devices in DSM’s Resource Monitor. If the CPU is maxed out, consider reducing the load by adjusting RAID sync or transfer priorities.
Update DSM and Firmware:
Ensure both NAS devices are running the latest version of DSM to benefit from performance optimizations.
Expected Performance Post-Optimization
With Jumbo Frames, Hyper Backup, and optimized SMB settings, you should see improved transfer rates, ideally in the range of 600–800MB/s for NAS-to-NAS and NAS-to-PC transfers.
If performance remains below expectations, the mixed drive setup in NAS 2 could be a limiting factor. Replacing smaller or slower drives with uniform, high-capacity models may improve performance.