PSA PSA PSA: if you use LVM with USB drives you will get absolutely *abysmal* performance by default (especially on HDDs). You must use `pvcreate --dataalignment 2048s` to fix it. Fix requires re-creating PV and copying all data.
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Apparently querying /sys/block/$disk/queue/physical_block_size was too hard??
The problem is they queried /sys/block/$disk/queue/optimal_io_size and trusted it over physical_block_size. And: # sg_inq -p 0xb0 /dev/sda [...] Optimal transfer length granularity: 8 blocks Maximum transfer length: 65535 blocks Optimal transfer length: 65535 blocks
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Is that normal for USB drives? My SanDisk Extreme reports 0 as optimal_io_size.
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I think it might be mostly UAS drives, perhaps only SATA bridges. I have at least two that do it from different vendors.
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