Hendrikx

I did some more tests, mounted a share on my Windows PC. Read transfer rate was consitant 200MB/s+ Write ranged from 170-200+MB/s Transfering a file from one share to another share (between disks) sits at around 90MB/s. So those speeds looks good, why is dd so slow when writing to a share but fast when writing to a disk.

I am seeing horrible write speeds to array, I do not know when this started, but I am pretty sure this has not always been the case. Writing directly to my disks are pretty fast: dd if=/dev/zero of=/mnt/disk5/test1.img bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.9644 s, 154 MB/s dd if=/dev/zero of=/mnt/disk4/test1.img bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.7702 s, 159 MB/s dd if=/dev/zero of=/mnt/disk3/media/test1.img bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.42448 s, 167 MB/s dd if=/dev/zero of=/mnt/disk2/media/test1.img bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.50934 s, 165 MB/s dd if=/dev/zero of=/mnt/disk1/media/test1.img bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 7.73002 s, 139 MB/s However as soon as I try to write to a share the speeds are HORRIBLE: Share is high-water, and consists of all 5 array disks, I have tried two different shares where it will write to two different disks. dd if=/dev/zero of=/mnt/user/test/test1.img bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 68.0992 s, 15.8 MB/s dd if=/dev/zero of=/mnt/user/media/test1.img bs=1G count=1 oflag=dsync 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 63.5272 s, 16.9 MB/s My setup: 2x16TB Parity 5x16TB Disks CPU sists idle pretty much when doing the tests: Intel® Core™ i5-14500 @ 4554 MHz I'll attach diagnostics. unraid-diagnostics-20250310-0917.zip