I don't think this is it. We do really have fragmentation and we do see it on most of the clusters regardless if flash pool is used or not and we are running OCPM 7.1 at the moment.
In statis output I see bad RAID statistics and 2:1 cpreads:writes
RAID Statistics (per second)
6735.19 xors 0.00 long dispatches [0]
0.00 long consumed [0] 0.00 long consumed hipri [0]
0.00 long low priority [0] 0.00 long high priority [0]
99.89 long monitor tics [0] 0.02 long monitor clears [0]
0.00 long dispatches [1] 0.00 long consumed [1]
0.00 long consumed hipri [1] 0.00 long low priority [1]
99.89 long high priority [1] 99.89 long monitor tics [1]
0.02 long monitor clears [1] 18 max batch
4.87 blocked mode xor 1142.43 timed mode xor
6.54 fast adjustments 7.73 slow adjustments
0 avg batch start 0 avg stripe/msec
0.00 checksum dispatches 0.00 checksum consumed
56.29 tetrises written 0.00 master tetrises
0.00 slave tetrises 3384.92 stripes written
3347.99 partial stripes 36.93 full stripes
28699.47 blocks written 26734.05 blocks read
20.66 1 blocks per stripe size 1 152.46 1 blocks per stripe size 20
179.10 2 blocks per stripe size 20 201.02 3 blocks per stripe size 20
218.03 4 blocks per stripe size 20 240.61 5 blocks per stripe size 20
251.40 6 blocks per stripe size 20 260.87 7 blocks per stripe size 20
261.86 8 blocks per stripe size 20 248.86 9 blocks per stripe size 20
229.94 10 blocks per stripe size 20 211.66 11 blocks per stripe size 20
193.01 12 blocks per stripe size 20 168.48 13 blocks per stripe size 20
144.02 14 blocks per stripe size 20 123.53 15 blocks per stripe size 20
99.40 16 blocks per stripe size 20 76.79 17 blocks per stripe size 20
55.66 18 blocks per stripe size 20 31.30 19 blocks per stripe size 20
16.27 20 blocks per stripe size 20
disk ut% xfers ureads--chain-usecs writes--chain-usecs cpreads-chain-usecs greads--chain-usecs gwrites-chain-usecs
/AGGR_ROOT_03/plex0/rg0:
0a.30.0 2 2.70 0.35 1.51 639 2.24 9.81 779 0.11 5.91 1001 0.00 .... . 0.00 .... .
0a.31.0 2 3.09 0.35 1.51 687 2.73 8.40 919 0.01 1.00 5732 0.00 .... . 0.00 .... .
4b.32.0 2 4.46 2.93 1.08 2835 1.04 19.88 377 0.48 1.00 5714 0.00 .... . 0.00 .... .
/AGGR_DATA_03/plex0/rg0:
4b.32.1 22 40.03 0.00 .... . 18.82 59.68 151 21.22 53.81 110 0.00 .... . 0.00 .... .
4b.31.1 23 40.86 0.00 .... . 19.66 57.20 163 21.20 53.76 118 0.00 .... . 0.00 .... .
0a.30.1 78 203.91 152.31 3.84 3550 16.00 29.72 615 35.59 10.52 1027 0.00 .... . 0.00 .... .
4b.32.2 75 205.12 154.42 3.83 2950 15.52 31.39 554 35.18 11.00 933 0.00 .... . 0.00 .... .
0a.31.2 75 206.01 155.64 3.78 3100 15.55 30.66 557 34.82 11.26 848 0.00 .... . 0.00 .... .
0a.30.2 79 206.50 155.46 3.83 3552 15.42 31.79 603 35.62 10.92 1046 0.00 .... . 0.00 .... .
4b.32.3 75 206.53 155.80 3.80 3080 15.90 31.29 571 34.83 11.67 840 0.00 .... . 0.00 .... .
4b.31.3 74 203.55 152.00 3.92 2812 15.46 31.63 564 36.09 10.82 934 0.00 .... . 0.00 .... .
0a.30.3 78 205.15 154.34 3.72 3615 15.52 30.74 590 35.29 11.00 951 0.00 .... . 0.00 .... .
4b.32.4 75 205.29 153.46 3.89 2993 15.53 30.75 589 36.31 10.81 942 0.00 .... . 0.00 .... .
0a.31.4 75 203.92 153.00 3.84 3040 15.36 30.40 572 35.55 10.70 955 0.00 .... . 0.00 .... .
0a.30.4 79 203.39 152.56 3.91 3519 15.37 29.95 631 35.45 11.01 991 0.00 .... . 0.00 .... .
4b.32.5 72 198.69 147.49 3.90 2796 15.52 31.59 536 35.68 11.03 866 0.00 .... . 0.00 .... .
4b.31.5 75 200.52 150.44 3.94 2906 15.40 30.92 554 34.68 10.96 919 0.00 .... . 0.00 .... .
0a.30.5 77 200.43 148.21 3.93 3440 15.76 30.49 598 36.46 10.91 942 0.00 .... . 0.00 .... .
4b.32.6 76 204.50 153.70 3.89 3019 15.56 31.83 612 35.24 11.04 939 0.00 .... . 0.00 .... .
0a.31.6 76 211.24 160.19 3.70 3059 15.48 31.64 559 35.57 11.06 910 0.00 .... . 0.00 .... .
0a.30.6 78 206.84 155.03 3.79 3545 15.66 30.25 601 36.15 10.67 1036 0.00 .... . 0.00 .... .
4b.32.7 75 207.19 156.46 3.81 2985 15.43 31.30 557 35.30 11.15 859 0.00 .... . 0.00 .... .
4b.31.7 75 207.70 157.63 3.88 2885 15.35 30.69 563 34.72 11.14 908 0.00 .... . 0.00 .... .
0a.30.7 78 201.06 149.99 3.91 3501 15.61 31.04 588 35.46 11.24 963 0.00 .... . 0.00 .... .
4b.32.8 74 204.21 153.27 3.76 3029 15.33 31.27 579 35.61 10.80 889 0.00 .... . 0.00 .... .
/AGGR_DATA_03/plex0/rg1:
0a.31.8 21 38.83 0.00 .... . 18.05 61.33 140 20.78 54.30 111 0.00 .... . 0.00 .... .
0a.30.8 22 39.07 0.00 .... . 18.31 60.49 147 20.76 54.29 113 0.00 .... . 0.00 .... .
4b.32.9 76 209.23 157.00 3.80 3037 15.64 30.20 580 36.59 10.98 894 0.00 .... . 0.00 .... .
4b.31.9 74 201.50 149.04 4.03 2753 15.64 30.40 567 36.82 10.92 927 0.00 .... . 0.00 .... .
0a.30.9 80 213.00 160.05 3.71 3690 15.58 30.78 615 37.37 10.65 1030 0.00 .... . 0.00 .... .
4b.32.10 74 210.20 158.12 3.87 2858 15.58 30.31 578 36.50 10.90 902 0.00 .... . 0.00 .... .
0a.31.10 75 211.73 160.03 3.87 2896 15.54 29.41 571 36.17 11.02 916 0.00 .... . 0.00 .... .
0a.30.10 79 207.73 155.23 3.94 3323 15.55 31.23 576 36.94 10.83 1031 0.00 .... . 0.00 .... .
4b.32.11 74 199.78 146.79 3.89 2940 15.46 30.21 560 37.53 10.88 918 0.00 .... . 0.00 .... .
4b.31.11 75 215.56 162.85 3.77 2936 15.42 30.67 557 37.29 10.78 967 0.00 .... . 0.00 .... .
0a.30.11 80 209.90 158.23 3.80 3627 15.53 30.01 628 36.14 11.02 1011 0.00 .... . 0.00 .... .
4b.32.12 74 204.92 152.36 3.73 3067 15.51 30.20 575 37.05 10.85 902 0.00 .... . 0.00 .... .
0a.31.12 76 210.26 157.36 3.98 2930 15.61 30.77 581 37.28 10.95 916 0.00 .... . 0.00 .... .
0a.30.12 79 208.94 156.94 3.77 3383 15.32 30.44 570 36.68 10.86 1061 0.00 .... . 0.00 .... .
4b.32.13 73 200.18 148.01 3.86 2998 15.37 30.66 586 36.80 10.73 920 0.00 .... . 0.00 .... .
4b.31.13 75 206.07 153.50 3.93 3050 15.52 30.68 591 37.05 10.68 952 0.00 .... . 0.00 .... .
0a.30.13 79 210.68 159.01 3.91 3587 15.35 30.28 628 36.32 11.17 1010 0.00 .... . 0.00 .... .
4b.32.14 75 215.53 162.97 3.70 3033 15.47 30.04 596 37.09 10.42 955 0.00 .... . 0.00 .... .
0a.31.14 75 208.71 156.31 3.91 2933 15.58 30.40 556 36.82 10.67 968 0.00 .... . 0.00 .... .
0a.30.14 78 208.60 156.47 3.87 3331 15.38 31.13 592 36.75 10.86 975 0.00 .... . 0.00 .... .
4b.32.15 76 213.41 160.78 3.86 2947 15.53 29.74 590 37.10 10.62 967 0.00 .... . 0.00 .... .
4b.31.15 76 213.52 161.41 3.66 3131 15.46 30.87 592 36.65 10.94 933 0.00 .... . 0.00 .... .
/AGGR_DATA_03/plex0/rg2:
4b.32.16 22 39.13 0.00 .... . 18.42 61.67 147 20.71 55.77 112 0.00 .... . 0.00 .... .
0a.30.15 22 39.38 0.00 .... . 18.70 60.80 145 20.69 55.71 109 0.00 .... . 0.00 .... .
0a.31.16 74 206.72 155.79 3.81 2759 15.51 31.00 508 35.42 11.25 861 0.00 .... . 0.00 .... .
4b.32.17 75 203.32 153.05 3.80 2983 15.56 30.48 539 34.70 11.57 817 0.00 .... . 0.00 .... .
0a.30.22 79 207.19 157.11 3.77 3437 15.58 31.52 551 34.50 11.26 951 0.00 .... . 0.00 .... .
4b.31.17 75 206.84 156.15 3.78 3003 15.60 31.31 533 35.09 11.21 885 0.00 .... . 0.00 .... .
4b.32.18 74 206.46 156.73 3.88 2796 15.35 31.23 541 34.38 11.36 860 0.00 .... . 0.00 .... .
0a.30.17 79 203.93 153.23 3.78 3518 15.52 30.45 588 35.17 11.00 991 0.00 .... . 0.00 .... .
0a.31.18 75 209.19 158.20 3.84 2883 15.51 31.05 546 35.48 11.20 904 0.00 .... . 0.00 .... .
4b.32.19 75 206.44 156.06 3.64 3185 15.38 31.45 535 35.00 11.43 880 0.00 .... . 0.00 .... .
0a.30.18 78 212.69 161.99 3.68 3373 15.37 31.37 558 35.33 11.15 1001 0.00 .... . 0.00 .... .
4b.31.19 75 205.36 153.75 3.85 2967 15.92 31.47 541 35.69 11.41 907 0.00 .... . 0.00 .... .
4b.32.20 74 211.59 161.04 3.71 2857 15.64 30.92 537 34.91 11.34 873 0.00 .... . 0.00 .... .
0a.30.19 78 206.73 155.74 3.69 3505 15.71 30.55 569 35.28 11.64 926 0.00 .... . 0.00 .... .
0a.31.20 75 210.89 160.87 3.76 2957 15.26 30.84 556 34.76 11.25 897 0.00 .... . 0.00 .... .
4b.32.21 74 202.38 151.96 3.88 2891 15.68 30.79 526 34.74 11.45 840 0.00 .... . 0.00 .... .
0a.30.20 79 203.98 153.04 3.93 3474 15.76 30.84 575 35.17 11.58 932 0.00 .... . 0.00 .... .
4b.31.21 75 211.86 161.03 3.81 2907 15.57 31.63 565 35.26 11.12 909 0.00 .... . 0.00 .... .
4b.32.22 75 205.53 154.98 3.81 3016 15.56 30.40 560 34.98 11.16 909 0.00 .... . 0.00 .... .
0a.30.21 78 204.44 153.64 3.89 3430 15.70 31.15 557 35.10 11.65 936 0.00 .... . 0.00 .... .
0a.31.22 75 210.42 159.52 3.78 2894 15.70 30.81 544 35.19 11.51 849 0.00 .... . 0.00 .... .
4b.32.23 74 202.89 153.08 3.66 3028 15.18 29.69 589 34.63 11.35 857 0.00 .... . 0.00 .... .
