>>>>> Stan Hoeppner <s...@hardwarefreak.com> writes:
[…]
> The horrible performance with bs=512 is likely due to the LVM block
> size being 4096, and forcing block writes that are 1/8th normal size,
> causing lots of merging. If you divide 120MB/s by 8 you get 15MB/s,
> which IIRC from your original post, is approximately the write
> performance you were seeing, which was 19MB/s.
I'm not an expert in that matter either, but I don't seem to
recall that LVM uses any “blocks”, other than, of course, the
LVM “extents.”
What's more important in my opinion is that 4096 is exactly the
platform's page size.
--cut: vgcreate(8) --
-s, --physicalextentsize PhysicalExtentSize[kKmMgGtT]
Sets the physical extent size on physical volumes of this volume
group. A size suffix (k for kilobytes up to t for terabytes) is
optional, megabytes is the default if no suffix is present. The
default is 4 MB and it must be at least 1 KB and a power of 2.
--cut: vgcreate(8) --
[…]
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