Write performance degraded inside virtual guests

Solution Verified - Updated -


  • Observed degraded write performance with the guests.
  • The host is a pure ssd setup, with 2 400G intel dc s3700 ssds, hardware raid1.
  • Without any virtual guests, it shows ~69k IOPS for read, ~38k IOPS for write
  • With only on virtual guest running on the host, the virtual guest shows ~50k IOPS for read, ~11k for write.
  • In terms of IOPS, read performance degraded to ~70% and write performance degraded to ~30%.
  • Both the host and guest is using deadline as the block scheduler, all using ext4.
  • The guest is using virtio-blk


  • Red Hat OpenStack 3.0

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