Date: Fri, 22 Oct 2010 15:52:36 -0700 From: "Eugene M. Kim" <gene@nttmcl.com> To: fs@freebsd.org Subject: ZFS: Parallel I/O to vdevs that appear to be separate physical disks but really are partitions Message-ID: <4CC215B4.3050607@nttmcl.com>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Greetings, I run a FreeBSD guest in VMware ESXi with a 10GB zpool. Lately the originally provisioned 10GB proved insufficient, and I would like to provision another 10GB virtual disk and add it to the zpool as a top-level vdev. The original and new virtual disks are from the same physical pool (a RAID-5 array), but appears to be separate physical disks to the FreeBSD guest (da0 and da1). I am afraid that the ZFS would schedule I/O to the two virtual disks in parallel thinking that the pool performance will improve, while the performance would actually suffer due to seeking back and forth between two regions of one physical pool. 1. Will ZFS schedule parallel access to different top-level vdevs? 2. If so, how can I suggest ZFS that certain vdevs should be treated not as separate physical disks but as partitions on the same physical disk? Regards, Eugene -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBAgAGBQJMwhWzAAoJEHSb/9O6h+h00RQP/3qZh063VpiOA4eT78WJyGtQ I4hVdp6ehwgKJV3wcNDWCkSlTguzQcIijVngKFEqVV2HWSgVZcXg8SMeW4yEkbTz uGGfTI8yNbncQo4J6LtJMG6rj0jhORwPVCvDlM8DiwYzNOdfqYgDf7y8qZogOQOf FErbxaq/D5i3tryoIv+5oyfPQ9LzlmCHl5WhOshOLD0eH/MyGW1MyJY8CDlpYRDl zhMtNMiYNox1QCuZXrK3KvQgbdPMSnCq8VkwHpBPhUHc78q3dZOpQT1erblvQrhv YQDNHBmuevoMiicmpBwYuBW8M6MTfMuIZ/r6lwF0mTUMm0Lwprn8wPZJgJ2F4Axq J1JrCyHYZq+GfU654bCMu+CxhptQf0/Ojytx2Ubvif6L9Afm4GFZO6iVuHvrRVob EmAfpEOXSCOV87BzAp+z3W5RDKDaK7bRFdqZmBEf/StmoLnVEbbxdoqUNM+IvXBu DimW3JZENHBv8046fRJXiQs7KLsBdBEcgdyxJpjjztaIo6mFt6FtHP0RzMCPTLr/ uXBGKgTC9LBOy7lXIFl6JmulMQ7u3hBXzlGtAxMWU/jxAyMm/LypsY1V1k9pnBUb Pxcbv8uv+UO0J43Yiw/t+hGEQ7IFtF0gNSU/q5r9C8nMAdJj2+GhGsO8sJyTTu8J Qg7/z8GY1OlXDfHm95zR =fh8Y -----END PGP SIGNATURE-----
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