> Also if its REF tag error, shouldn't I have seen the same issue with > 4K+ 8B meta data? fio works fine with 4K+8 format. When PI was originally added to SCSI, the only PI size defined was 8 bytes. I don't know if the kernel supports 64 bytes, and what it puts there if it does. It's possible that reading a block before it's been written could trigger PI errors, since the PI content is uninitialized. I don't think fio ever does that (even with a verify thread) - the --debug=io option will show all the IOs that it generates. Check if the kernel log reports problems while running some other application (e.g., dd). What are all those reads to LBA 3750748672? Something is looking for partition tables? You're using direct=1 so the page cache shouldn't be doing prefetching.
