SATA disk attached to KVM VM has very poor performance

by sushma   Last Updated August 01, 2019 16:00 PM

I have CentOS 7.3 Host with 12 SATA disk Enclosure attached to it. In one of the disk I have created 2 partitions 1 as 1MB and remaining size as other one. Formatted the larger partition with XFS file system and mounted it. Ran FIO sequential write tests on it and got throughput around 400 MBPS. Same SATA disk attached to KVM based Fedora Core 13 guest as SATA raw disk with IO Mode as 'native' and Cache mode as 'none'. Ran the same FIO tests as host and got throughput around 180-200 MBPS. Got the same performance even after changing disk IO Mode to 'threads'. To get host level performance in guest what other KVM parameters need to change.

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