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<div>Hi,</div>
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<div>I have observed (via iostat) dm-cache is writing to source device also in write back mode (equivalent to IOS going to cache device) even though cache is filled with 25% cache size.</div>
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<div>Any explanation as to why this behavior when it is expected that none of the IOS (random 4 K writes) should be going to source device in write back mode?</div>
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<div>Thanks,</div>
<div>#Girish_BK</div>
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<div><b><u>Here are test parameters:</u></b></div>
<div>RHEL: 7.0 (3.19 kernel)</div>
<div>Dm-cache policy set to ‘write back’ and cache block size set to 32K.</div>
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<div><span style="color: rgb(31, 73, 125); font-size: 15px;">0 16384000 cache 8 637/2048000 64 17/256000 189 84 84 524204 0 17 0 1 writeback 2 migration_threshold 2048 mq 10 random_threshold 4 sequential_threshold 512 discard_promote_adjustment 1 read_promote_adjustment
4 write_promote_adjustment 8</span></div>
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<div>Test run was with fio: Random 4K write (100%) </div>
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