Peter Grandi schrieb:
Those are as such not very meaningful. What matters most is whether the starting physical address of each logical volume extent is stripe aligned (and whether the filesystem makes use of that) and then the stripe size of the parity RAID set, not the chunk sizes in themselves. I am often surprised by how many people who use parity RAID don't seem to realize the crucial importance of physical stripe alignment, but I am getting used to it.
Am I right to assume that stripe alignment matters because of the read-modify-write cycle needed for unaligned writes? If so, how come a pure read benchmark (hdparm -t or plain dd) is slower on the LVM device than on the md device?
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