I reinitialized to 4096B sector size (LBA Format 1) and experienced a performance drop. I was under the impression that switching to advanced format (the 4096 Byte sector size interface) would be beneficial to performance. I run all the latest (Linux) software on an Intel Q65 chipset (PCIe v2 with 4 PCIe lanes dedicated to the NVMe drive).
Before:
Performance @ 512B sector interface (LBA Format 0):
root@xubuntu:~# hdparm -t /dev/nvme0n1p1 /dev/nvme0n1p1: Timing buffered disk reads: 4658 MB in 3.00 seconds = 1552.07 MB/sec
After:
Performance @ 4096B sector interface (LBA Format 1):
# hdparm -t /dev/nvme0n1p1 /dev/nvme0n1p1: Timing buffered disk reads: 2844 MB in 3.00 seconds = 947.51 MB/sec
Seq read performance dropped from 1552.07 MB/sec to 947.51 MB/sec, whereas one would expect a performance gain.
What is going on here?
I verified alignment of the logical file system clusters to the physical sector size of 4096B, it should be okay:
$ sudo parted /dev/nvme0n1 GNU Parted 3.3 Using /dev/nvme0n1 Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Model: WDC WDS500G2B0C-00PXH0 (nvme) Disk /dev/nvme0n1: 500GB Sector size (logical/physical): 4096B/4096B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 300GB 500GB 200GB ext4 ubuntu-root (parted) align-check opt 1 1 aligned
What is the internal physical sector size, that the SN550 NVMe drive uses?
WD please help out here? Why do I get a drop in performance when re-initializing to the 4096B sector size?
How can I get the expected performance gain from going to 4096B sector size (advanced format).
