I'm with Jeff... Looks like CP-Reads. (Need to read from disk to be able to calculate parity. Happens when unable to write 'full stripes', e.g. full aggregate)
Do statit and check your disk statistics:
uread = User Reads, writes = User writes, cpread = CP Read as described above, gread+gwrite = guaranteed writes, like for disk rebuild
Tell us what you find :-)
Sebastian
On 10/21/2013 4:28 PM, Alon Zeltser wrote:
Hello toasters
I encounter rather strange situation
I have a system FAS2040 with 1 aggr of 23x450g raid group ontap version 8.1.3p2
Every write operation being generated on this aggregate automatically caused a read operation
When I try to create 100% sequential write operation using tools such as sio_ntap or filersio
Instead of the expected 150Mb throughput I get 100MB write and 50MB read
On another FAS2040 system using the same commands I get 100% write and no reads
As you can see
filersio asyncio_active 0 -r 0 64k 0 15g 60 1 /vol/test/testfile
CPU NFS CIFS HTTP Total Net kB/s Disk kB/s Tape kB/s Cache Cache CP CP Disk OTHER FCP iSCSI FCP kB/s iSCSI kB/s
93% 0 0 0 5 26 1 *24242 118671 * 0 0 0s 99% 72% Fn 43% 0 0 5 0 0 24 0
90% 0 0 0 4 4 1 *40959 102501
- 0 0 19 100% 89% Fn 43% 1 0 3
0 0 2 0
86% 0 0 0 3 3 1 *23126 125022
- 0 0 0s 99% 69% : 59% 0 0 3
0 0 2 0
93% 0 0 0 7 1 1 *28200 135740
- 0 0 0s 99% 97% Ff 48% 7 0 0
0 0 0 0
92% 0 0 0 6 15 1 * 48764 115324
- 0 0 0s 99% 91% Ff 52% 0 0 6
0 0 14 0
90% 0 0 0 6 16 1 * 36148 156492
- 0 0 0s 99% 83% Ff 56% 0 0 6
0 0 14 0
95% 0 0 0 0 4 4 *32784 114555
- 0 0 0s 99% 77% Fs 48% 0 0 0 0 0 0 0
92% 0 0 0 18 90 1*2 34931 104059
0 0 0s 99% 88% Fn 42% 0 018 0 0 79 0
88% 0 0 0 8 3 1 *20463 124800
- 0 0 0s 100% 83% Fn 45% 5 0 3
0 0 2 0
89% 0 0 0 2 2 1 *34050 112166
- 0 0 0s 99% 87% Fn 44% 0 0 2
0 0 1 0
92% 0 0 0 3 7 1 *33025 112816
- 0 0 0s 99% 88% Fn 46% 0 0 3
0 0 5 0
91% 0 0 0 3 3 1 *30929 130833
- 0 0 0s 100% 73% : 50% 0 0 3
0 0 2 0
92% 0 0 0 7 24 2 * 36484 134260
- 0 0 0s 100% 98% Ff 50% 0 0 7
0 0 22 0
86% 0 0 0 6 1 1 *38608 125140
- 0 0 0s 99% 90% Ff 44% 5 0 1
0 0 1 0
93% 0 0 0 4 3 1 *28748 104544
- 0 0 0s 100% 75% Ff 43% 0 0 4
0 0 2 0
87% 0 0 0 5 18 1 * 28128 158608
- 0 0 0s 100% 90% Fs 55% 0 0 5
0 0 17 0
93% 0 0 0 2 3 34 * 33115 104980
- 0 0 0s 99% 85% Fn 41% 0 0 2
0 0 1 32
84% 0 0 0 5 28 7 * 37185 109425
- 0 0 0s 100% 78% Fn 48% 0 0 5
0 0 21 0
91% 0 0 0 9 3 1 *30224 118322
- 0 0 0s 99% 97% Fn 47% 7 0 2
0 0 1 0
89% 0 0 0 2 3 4 *27649 118335
- 0 0 0s 99% 88% : 45% 0 0 2
0 0 1 0
CPU NFS CIFS HTTP Total Net kB/s Disk kB/s Tape kB/s Cache Cache CP CP Disk OTHER FCP iSCSI FCP kB/s iSCSI kB/s
in out read write read write age hit time ty util in out in out
88% 0 0 0 14 57 39 * 43284 13348*0 0 0 0s 100% 98% Ff 50% 0 0 14 0 0 52 0
92% 0 0 0 2 6 16 *47936 109432* 0 0 0s 99% 86% Ff 46% 0 0 2 0 0 1 0
88% 0 0 0 23 86 3 * 45340 141014* 0 0 0s 99% 73% Ff 55% 3 0 20 0 0 82 0
92% 0 0 0 10 5 4 *21787 123980* 0 0 0s 99% 80% Fn 44% 7 0 3 0 0 1 0
95% 0 0 0 2 4 3 *34751 98158
- 0 0 0s 99% 82% Fn 44% 0 0 2
0 0 1 0
91% 0 0 0 1 3 1 *35022 118549
0 0 0s 100% 60% Fn 48% 0 0 10 0 0 0
92% 0 0 0 87 3 1 *25455 123066* 0 0 0s 100% 80% Fn 47% 84 0 3 0 0 1 0
83% 0 0 0 8 32 2 *36956 121303* 0 0 0s 100% 88% : 46% 0 0 8 0 0 30 0
85% 0 0 0 5 2 1 *62064 140088
0 0 0s 100% 92% Ff 59% 5 0 00 0 0 0
95% 0 0 0 3 3 1 *39352 117364
0 0 0s 99% 71% Ff 48% 0 0 30 0 2 0
94% 0 0 0 3 3 1 *42008 136943
0 0 0s 99% 94% Fs 53% 0 0 30 0 2 0
92% 0 0 0 0 2 7 *26147 111286
0 0 0s 99% 58% Fn 44% 0 0 00 0 0 0
90% 0 0 0 3 3 1 *29567 110665
0 0 20 99% 87% Fn 44% 0 0 30 0 1 0
90% 0 0 0 9 4 1 *40031 111273
0 0 16 99% 86% Fn 43% 5 0 40 0 2 0
84% 0 0 0 0 1 1 *36760 105709
0 0 0s 100% 84% Fn 43% 0 0 00 0 0 0
92% 0 0 0 3 3 1 *31033 137891
0 0 0s 100% 99% : 53% 0 0 30 0 2 0
83% 0 0 0 4 6 1 *32991 140148
0 0 0s 100% 89% F 51% 0 0 40 0 5 0
Any thoughts why this could happens ?
Nothing else is running on this netapp except for this test
Thanks
Alon Z
Toasters mailing list Toasters@teaparty.net http://www.teaparty.net/mailman/listinfo/toasters