I have a striped logical volume that consists of 20 underlying
physical volumes. iostat shows that the underlying physical disks
usually stay under 20% utilization, but the device representing the
logical volume sits at 100% utilization near constantly.
I'm not sure how reliable "utilization" in iostat is, but how I came
across this was the considerable iowait being displayed on this server
- usually 2 of the 8 CPUs sit near 98% wait.
So, a couple questions I couldn't seem to answer myself:
* Is 20 physical volumes a reasonable size?
* Is the discrepancy I'm seeing between PV's and the LV LVM overhead?
I appreciate the help.
Chris
Some details:
[root@ bin]# lvdisplay -m /dev/tsmstgvg/tsmdisk1
--- Logical volume ---
LV Name /dev/tsmstgvg/tsmdisk1
VG Name tsmstgvg
LV UUID dj2CFo-sK0q-1GvQ-Gpd5-6Hea-Aul1-QLEMwI
LV Write Access read/write
LV Status available
# open 1
LV Size 8.30 TB
Current LE 68000
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 10240
Block device 253:8
--- Segments ---
Logical extent 0 to 67999:
Type striped
Stripes 20
Stripe size 128 KB
Stripe 0:
Physical volume /dev/emcpowera
Physical extents 0 to 3399
Stripe 1:
Physical volume /dev/emcpowerr
Physical extents 0 to 3399
Stripe 2:
Physical volume /dev/emcpowers
Physical extents 0 to 3399
Stripe 3:
Physical volume /dev/emcpowerd
Physical extents 0 to 3399
Stripe 4:
Physical volume /dev/emcpowert
Physical extents 0 to 3399
Stripe 5:
Physical volume /dev/emcpoweru
Physical extents 0 to 3399
Stripe 6:
Physical volume /dev/emcpowerf
Physical extents 0 to 3399
Stripe 7:
Physical volume /dev/emcpowerv
Physical extents 0 to 3399
Stripe 8:
Physical volume /dev/emcpowerw
Physical extents 0 to 3399
Stripe 9:
Physical volume /dev/emcpowerh
Physical extents 0 to 3399
Stripe 10:
Physical volume /dev/emcpowerx
Physical extents 0 to 3399
Stripe 11:
Physical volume /dev/emcpoweri
Physical extents 0 to 3399
Stripe 12:
Physical volume /dev/emcpowerj
Physical extents 0 to 3399
Stripe 13:
Physical volume /dev/emcpowerk
Physical extents 0 to 3399
Stripe 14:
Physical volume /dev/emcpowerl
Physical extents 0 to 3399
Stripe 15:
Physical volume /dev/emcpowerm
Physical extents 0 to 3399
Stripe 16:
Physical volume /dev/emcpowern
Physical extents 0 to 3399
Stripe 17:
Physical volume /dev/emcpowero
Physical extents 0 to 3399
Stripe 18:
Physical volume /dev/emcpowerp
Physical extents 0 to 3399
Stripe 19:
Physical volume /dev/emcpowerq
Physical extents 0 to 3399
[root@ bin]# iostat 1 2 -xm /dev/emcpowera /dev/emcpowerd
/dev/emcpowerf /dev/emcpowerh /dev/emcpoweri /dev/emcpowerj
/dev/emcpowerk /dev/emcpowerl /dev/emcpowerm /dev/emcpowern
/dev/emcpowero /dev/emcpowerp /dev/emcpowerq /dev/emcpowerr
/dev/emcpowers /dev/emcpowert /dev/emcpoweru /dev/emcpowerv
/dev/emcpowerw /dev/emcpowerx dm-8
avg-cpu: %user %nice %system %iowait %steal %idle
1.12 0.00 0.87 18.60 0.00 79.40
Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz
avgqu-sz await svctm %util
emcpowerp 1.00 0.00 19.00 16.00 1.32 0.83 126.17
0.29 8.40 7.94 27.80
emcpowero 0.00 0.00 16.00 39.00 1.38 0.88 84.07
0.25 4.64 2.07 11.40
emcpowerl 0.00 0.00 23.00 9.00 1.71 0.57 145.75
0.14 4.44 4.16 13.30
emcpowerk 0.00 0.00 16.00 8.00 1.50 0.72 190.00
0.14 5.62 5.54 13.30
emcpowerj 0.00 0.00 22.00 10.00 1.55 0.85 153.50
0.16 4.88 4.84 15.50
emcpoweri 10.00 0.00 19.00 11.00 1.71 0.88 177.07
0.16 5.23 4.90 14.70
emcpowern 0.00 0.00 20.00 19.00 1.54 0.84 124.51
0.17 4.31 4.00 15.60
emcpowerd 0.00 0.00 15.00 13.00 1.34 0.65 145.43
0.11 3.96 3.71 10.40
emcpowerh 1.00 0.00 21.00 12.00 1.96 0.88 175.76
0.18 5.45 5.24 17.30
emcpowera 2.00 0.00 21.00 11.00 1.21 0.81 129.75
0.18 5.72 4.31 13.80
emcpowerf 10.00 0.00 27.00 28.00 1.80 0.73 94.40
0.21 4.15 2.69 14.80
emcpowerx 16.00 0.00 28.00 20.00 1.88 0.91 119.00
0.21 4.46 3.65 17.50
emcpowerw 15.00 0.00 30.00 12.00 2.00 0.98 145.14
0.20 4.79 4.50 18.90
emcpowerv 31.00 0.00 21.00 10.00 1.88 0.86 181.16
0.16 5.03 4.90 15.20
emcpowerq 13.00 0.00 17.00 8.00 1.30 0.78 169.92
0.18 7.12 5.52 13.80
emcpoweru 0.00 0.00 16.00 31.00 1.48 0.72 96.00
0.37 7.81 6.43 30.20
emcpowerm 0.00 0.00 18.00 7.00 1.62 0.65 186.24
0.14 5.52 5.28 13.20
emcpowert 0.00 0.00 19.00 13.00 1.35 0.71 131.75
0.31 9.72 9.53 30.50
emcpowers 9.00 0.00 20.00 11.00 1.30 0.75 136.00
0.13 4.06 3.90 12.10
emcpowerr 0.00 0.00 13.00 8.00 1.20 0.75 189.71
0.12 5.71 4.86 10.20
dm-8 0.00 0.00 267.00 175.00 31.23 15.75
217.70 3.16 7.36 2.27 100.20
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