> 1) Which file system are you using? >From Linux's view it's ext4. Real vmdx file on Hyper-V is stored on NTFS, as far as I know.
> 2) What is the segment layout of the LVM PVs and LVs? I am a bit lost with it. Is that what you are asking about? master: # pvs --segments PV VG Fmt Attr PSize PFree Start SSize /dev/sda5 ubuntu-vg lvm2 a-- 19.76g 20.00m 0 4926 /dev/sda5 ubuntu-vg lvm2 a-- 19.76g 20.00m 4926 127 /dev/sda5 ubuntu-vg lvm2 a-- 19.76g 20.00m 5053 5 # lvs --segments LV VG Attr #Str Type SSize root ubuntu-vg -wi-ao--- 1 linear 19.24g swap_1 ubuntu-vg -wi-ao--- 1 linear 508.00m slave: # pvs --segments PV VG Fmt Attr PSize PFree Start SSize /dev/sda3 postgresnlpslave-vg lvm2 a-- 429.77g 0 0 110021 /dev/sda5 postgresnlpslave-vg lvm2 a-- 169.52g 0 0 28392 /dev/sda5 postgresnlpslave-vg lvm2 a-- 169.52g 0 28392 2199 /dev/sda5 postgresnlpslave-vg lvm2 a-- 169.52g 0 30591 2560 /dev/sda5 postgresnlpslave-vg lvm2 a-- 169.52g 0 33151 10246 /dev/sdb1 postgresnlpslave-vg lvm2 a-- 512.00g 0 0 131071 # lvs --segments LV VG Attr #Str Type SSize root postgresnlpslave-vg -wi-ao---- 1 linear 110.91g root postgresnlpslave-vg -wi-ao---- 1 linear 40.02g root postgresnlpslave-vg -wi-ao---- 1 linear 10.00g root postgresnlpslave-vg -wi-ao---- 1 linear 429.77g root postgresnlpslave-vg -wi-ao---- 1 linear 512.00g swap_1 postgresnlpslave-vg -wi-ao---- 1 linear 8.59g > 3) Do you use LVM for any "extra" features, such as snapshots? I don't think so, but how to check? vgs gives #SN = 0, is that it? > 4) You can try using seekwatcher to see where on the disk the slowness is occurring. You get a chart similar to this http://kernel.dk/dd-md0-xfs-pdflush.png > 5) BCC is a collection of tools that might shed a light on what is happening. https://github.com/iovisor/bcc Will look into it. Regards, Vlad