Date: Mon, 4 Dec 2017 17:19:49 -0600 From: Dustin Wenz <dustinwenz@ebureau.com> To: freebsd-virtualization@freebsd.org Subject: Storage overhead on zvols Message-ID: <CC62E200-A749-4406-AC56-2FC7A104D353@ebureau.com>
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--Apple-Mail=_85D4250D-350C-413F-9A10-3C65744412EA Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii I'm starting a new thread based on the previous discussion in "bhyve = uses all available memory during IO-intensive operations" relating to = size inflation of bhyve data stored on zvols. I've done some = experimenting with this, and I think it will be useful for others. The zvols listed here were created with this command: zfs create -o volmode=3Ddev -o volblocksize=3DXk -V 30g = vm00/chyves/guests/myguest/diskY The zvols were created on a raidz1 pool of four disks. For each zvol, I = created a basic zfs filesystem in the guest using all default tuning = (128k recordsize, etc). I then copied the same 8.2GB dataset to each = filesystem. volblocksize size amplification 512B 11.7x 4k 1.45x 8k 1.45x 16k 1.5x 32k 1.65x 64k 1x 128k 1x The worst case is with a 512B volblocksize, where the space used is more = than 11 times the size of the data stored within the guest. The size = efficiency gains are non-linear as I continue from 4k and double the = block sizes; 32k blocks being the second-worst. The amount of wasted = space was minimized by using 64k and 128k blocks. It would appear that 64k is a good choice for volblocksize if you are = using a zvol to back your VM, and the VM is using the virtual device for = a zpool. Incidentally, I believe this is the default when creating VMs = in FreeNAS. - .Dustin --Apple-Mail=_85D4250D-350C-413F-9A10-3C65744412EA Content-Disposition: attachment; filename=smime.p7s Content-Type: application/pkcs7-signature; name=smime.p7s Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIEzDCCBMgw ggOwoAMCAQICAUEwDQYJKoZIhvcNAQELBQAwgZkxCzAJBgNVBAYTAlVTMRIwEAYDVQQIEwlNaW5u ZXNvdGExFDASBgNVBAcTC1NhaW50IENsb3VkMRAwDgYDVQQKEwdlQnVyZWF1MRQwEgYDVQQLEwtJ bnRlZ3JhdGlvbjEUMBIGA1UEAxMLZWJ1cmVhdS5jb20xIjAgBgkqhkiG9w0BCQEWE3N1cHBvcnRA ZWJ1cmVhdS5jb20wHhcNMTcwNTA1MTYxNjE1WhcNMjcwNTAzMTYxNjE1WjBKMQswCQYDVQQGEwJV UzEUMBIGA1UEAwwLRHVzdGluIFdlbnoxJTAjBgkqhkiG9w0BCQEWFmR1c3RpbndlbnpAZWJ1cmVh dS5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQCQ/HJXe7JhUaexqEaxCNVifsue sUMgohgXLmi5YIcbAWhdxTr1PUzKYkeTkL9sYNjXU6uaI2tZMF3hA9gcFjxQIfkKSo31MrYOgMdU xQe0Q+t6Vd4pGAmtDQDwhAsrNGccADp3Yjy4eBtVfkDGdzz1Y8Lbc684TPFcW7i9+U/dDaXlcxeq fyDqiHZ5y8Lp/1M2Ot/Rz7eikJZTAuHOWKs/PEiJIM2JHuhPyNy+mL2oqEWeOcEsKMNzgn7HVt4k Xz2irBAG+cj4WAxWs418l46EEXgur4PvhBXZMl0LJg0TyaxOHbsUam4R4tbKnaZ3HhRkg79k2Had sb6DKbnCw9/1AgMBAAGjggFnMIIBYzAJBgNVHRMEAjAAMAsGA1UdDwQEAwIE8DAnBgNVHSUEIDAe BggrBgEFBQcDAQYIKwYBBQUHAwIGCCsGAQUFBwMEMB0GA1UdDgQWBBTLi/8HUHpbBEt9OtPqQoax AmpaNDCBzgYDVR0jBIHGMIHDgBRnpZeXB5rQYLgsUKqiiBcLIHyu6aGBn6SBnDCBmTELMAkGA1UE BhMCVVMxEjAQBgNVBAgTCU1pbm5lc290YTEUMBIGA1UEBxMLU2FpbnQgQ2xvdWQxEDAOBgNVBAoT B2VCdXJlYXUxFDASBgNVBAsTC0ludGVncmF0aW9uMRQwEgYDVQQDEwtlYnVyZWF1LmNvbTEiMCAG CSqGSIb3DQEJARYTc3VwcG9ydEBlYnVyZWF1LmNvbYIJAMwZcjAWAsWXMDAGCWCGSAGG+EIBBAQj FiFodHRwOi8vd3d3LmVidXJlYXUuY29tL2NhLWNybC5wZW0wDQYJKoZIhvcNAQELBQADggEBAHbO qVdB9raUKXCgZRA/nES5a60dlIaGnIlpgz+Y3SjFt0bcJxoUYhIzumBHk9yjyP4M1DubOphkQpJ4 LNZbAS01cjCxjnC0ZUq5V3FCeaDwrn1qPY+QJGoZPLlhWdJUNu17OpnR7ZfBWlp3/pRhvNU5PCbJ nmF7rnvsqxUFq9oeiV3SmqBux5lwJ7p2Uss5SHSW6g17K/KdTMK1roQr/+rWpxp2233qddDrLpOE xGRlvhEqSa/IZbGC9oiYmsiaG1PefQkadoob5IMIS5/MDpWHUgSHqAj1V/LwcCx0rbt73SazGMND EzHVWhsj+khepB/MG5QGfWP23IGFmvQYWWcxggOQMIIDjAIBATCBnzCBmTELMAkGA1UEBhMCVVMx EjAQBgNVBAgTCU1pbm5lc290YTEUMBIGA1UEBxMLU2FpbnQgQ2xvdWQxEDAOBgNVBAoTB2VCdXJl YXUxFDASBgNVBAsTC0ludGVncmF0aW9uMRQwEgYDVQQDEwtlYnVyZWF1LmNvbTEiMCAGCSqGSIb3 DQEJARYTc3VwcG9ydEBlYnVyZWF1LmNvbQIBQTAJBgUrDgMCGgUAoIIBxTAYBgkqhkiG9w0BCQMx CwYJKoZIhvcNAQcBMBwGCSqGSIb3DQEJBTEPFw0xNzEyMDQyMzE5NTBaMCMGCSqGSIb3DQEJBDEW BBQuj8Vux5VGF1eV5QvzsJ2iiC5v5TCBsAYJKwYBBAGCNxAEMYGiMIGfMIGZMQswCQYDVQQGEwJV UzESMBAGA1UECBMJTWlubmVzb3RhMRQwEgYDVQQHEwtTYWludCBDbG91ZDEQMA4GA1UEChMHZUJ1 cmVhdTEUMBIGA1UECxMLSW50ZWdyYXRpb24xFDASBgNVBAMTC2VidXJlYXUuY29tMSIwIAYJKoZI hvcNAQkBFhNzdXBwb3J0QGVidXJlYXUuY29tAgFBMIGyBgsqhkiG9w0BCRACCzGBoqCBnzCBmTEL MAkGA1UEBhMCVVMxEjAQBgNVBAgTCU1pbm5lc290YTEUMBIGA1UEBxMLU2FpbnQgQ2xvdWQxEDAO BgNVBAoTB2VCdXJlYXUxFDASBgNVBAsTC0ludGVncmF0aW9uMRQwEgYDVQQDEwtlYnVyZWF1LmNv bTEiMCAGCSqGSIb3DQEJARYTc3VwcG9ydEBlYnVyZWF1LmNvbQIBQTANBgkqhkiG9w0BAQEFAASC AQCJO3mtHogCOS/EAfrWZu6MwXrvP+4waW/G2r4W9k6qI9hAVJGwbQjAxdZSCTJzjnYg97jBc93A aHO1cb2uo3fKp+T6s29ainCvFfe7uAC+MHwLJ5qPHXk9lQvGpyyA/Fg3FlOzOtbUP14epJ3d317m IajFIYG0xL1oiYTjqzWALeCYq/O45P71hcTS1cIvQyK+10L39xe2RIjr41DyL7UowOZWvrlsHixp wa5nO59uroXbtcWZka7/TTMveCkpZl0MalQKPdlea+BAuuGiLYib7S9T73ggV+xK0S5pBRNyUgdp Bk7fsL6yL6e5IR9xbNn8jRXzm7xC4XprnWPIevd7AAAAAAAA --Apple-Mail=_85D4250D-350C-413F-9A10-3C65744412EA--
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