Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Wf6u2-0006m7-GU for pgsql-performance@arkaria.postgresql.org; Tue, 29 Apr 2014 12:12:50 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1Wf6u1-0002NH-OZ for pgsql-performance@arkaria.postgresql.org; Tue, 29 Apr 2014 12:12:49 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Wf6u0-0002MN-GD for pgsql-performance@postgresql.org; Tue, 29 Apr 2014 12:12:48 +0000 Received: from wsip-70-169-168-7.pn.at.cox.net ([70.169.168.7] helo=fs.denninger.net) by magus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Wf6tw-0003Y7-SB for pgsql-performance@postgresql.org; Tue, 29 Apr 2014 12:12:47 +0000 Received: from [127.0.0.1] (localhost [127.0.0.1]) by fs.denninger.net (8.14.8/8.14.8) with ESMTP id s3TCCg8Q004830 for ; Tue, 29 Apr 2014 07:12:42 -0500 (CDT) (envelope-from karl@denninger.net) Received: from [127.0.0.1] (TLS/SSL) [192.168.1.40] by Spamblock-sys (LOCAL/AUTH); Tue Apr 29 07:12:42 2014 Message-ID: <535F9735.1070503@denninger.net> Date: Tue, 29 Apr 2014 07:12:37 -0500 From: Karl Denninger User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: "pgsql-performance@postgresql.org" Subject: Re: Revisiting disk layout on ZFS systems References: <535E781A.5030708@denninger.net> In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms050909090602050504020304" X-Antivirus: avast! (VPS 140428-1, 04/28/2014), Outbound message X-Antivirus-Status: Clean X-Pg-Spam-Score: -0.9 (/) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org This is a cryptographically signed message in MIME format. --------------ms050909090602050504020304 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable On 4/29/2014 3:13 AM, Albe Laurenz wrote: > Karl Denninger wrote: >> I've been doing a bit of benchmarking and real-world performance >> testing, and have found some curious results. > [...] > >> The odd thing is that I am getting better performance with a 128k reco= rd >> size on this application than I get with an 8k one! > [...] > >> What I am curious about, however, is the xlog -- that appears to suffe= r >> pretty badly from 128k record size, although it compresses even >> more-materially; 1.94x (!) >> >> The files in the xlog directory are large (16MB each) and thus "first >> blush" would be that having a larger record size for that storage area= >> would help. It appears that instead it hurts. > As has been explained, the access patterns for WAL are quite different.= > > For your experiment, I'd keep them on different file systems so that > you can tune them independently. > They're on physically-different packs (pools and groups of spindles) as=20 that has been best practice for performance reasons pretty-much always=20 -- I just thought it was interesting, and worth noting, that the usual=20 recommendation to run an 8k record size for the data store itself may no = longer be valid. It certainly isn't with my workload. --=20 -- Karl karl@denninger.net --------------ms050909090602050504020304 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIFTzCC BUswggQzoAMCAQICAQgwDQYJKoZIhvcNAQEFBQAwgZ0xCzAJBgNVBAYTAlVTMRAwDgYDVQQI EwdGbG9yaWRhMRIwEAYDVQQHEwlOaWNldmlsbGUxGTAXBgNVBAoTEEN1ZGEgU3lzdGVtcyBM TEMxHDAaBgNVBAMTE0N1ZGEgU3lzdGVtcyBMTEMgQ0ExLzAtBgkqhkiG9w0BCQEWIGN1c3Rv bWVyLXNlcnZpY2VAY3VkYXN5c3RlbXMubmV0MB4XDTEzMDgyNDE5MDM0NFoXDTE4MDgyMzE5 MDM0NFowWzELMAkGA1UEBhMCVVMxEDAOBgNVBAgTB0Zsb3JpZGExFzAVBgNVBAMTDkthcmwg RGVubmluZ2VyMSEwHwYJKoZIhvcNAQkBFhJrYXJsQGRlbm5pbmdlci5uZXQwggIiMA0GCSqG SIb3DQEBAQUAA4ICDwAwggIKAoICAQC5n2KBrBmG22nVntVdvgKCB9UcnapNThrW1L+dq6th d9l4mj+qYMUpJ+8I0rTbY1dn21IXQBoBQmy8t1doKwmTdQ59F0FwZEPt/fGbRgBKVt3Quf6W 6n7kRk9MG6gdD7V9vPpFV41e+5MWYtqGWY3ScDP8SyYLjL/Xgr+5KFKkDfuubK8DeNqdLniV jHo/vqmIgO+6NgzPGPgmbutzFQXlxUqjiNAAKzF2+Tkddi+WKABrcc/EqnBb0X8GdqcIamO5 SyVmuM+7Zdns7D9pcV16zMMQ8LfNFQCDvbCuuQKMDg2F22x5ekYXpwjqTyfjcHBkWC8vFNoY 5aFMdyiN/Kkz0/kduP2ekYOgkRqcShfLEcG9SQ4LQZgqjMpTjSOGzBr3tOvVn5LkSJSHW2Z8 Q0dxSkvFG2/lsOWFbwQeeZSaBi5vRZCYCOf5tRd1+E93FyQfpt4vsrXshIAk7IK7f0qXvxP4 GDli5PKIEubD2Bn+gp3vB/DkfKySh5NBHVB+OPCoXRUWBkQxme65wBO02OZZt0k8Iq0i4Rci WV6z+lQHqDKtaVGgMsHn6PoeYhjf5Al5SP+U3imTjF2aCca1iDB5JOccX04MNljvifXgcbJN nkMgrzmm1ZgJ1PLur/ADWPlnz45quOhHg1TfUCLfI/DzgG7Z6u+oy4siQuFr9QT0MQIDAQAB o4HWMIHTMAkGA1UdEwQCMAAwEQYJYIZIAYb4QgEBBAQDAgWgMAsGA1UdDwQEAwIF4DAsBglg hkgBhvhCAQ0EHxYdT3BlblNTTCBHZW5lcmF0ZWQgQ2VydGlmaWNhdGUwHQYDVR0OBBYEFHw4 +LnuALyLA5Cgy7T5ZAX1WzKPMB8GA1UdIwQYMBaAFF3U3hpBZq40HB5VM7B44/gmXiI0MDgG CWCGSAGG+EIBAwQrFilodHRwczovL2N1ZGFzeXN0ZW1zLm5ldDoxMTQ0My9yZXZva2VkLmNy bDANBgkqhkiG9w0BAQUFAAOCAQEAZ0L4tQbBd0hd4wuw/YVqEBDDXJ54q2AoqQAmsOlnoxLO 31ehM/LvrTIP4yK2u1VmXtUumQ4Ao15JFM+xmwqtEGsh70RRrfVBAGd7KOZ3GB39FP2TgN/c L5fJKVxOqvEnW6cL9QtvUlcM3hXg8kDv60OB+LIcSE/P3/s+0tEpWPjxm3LHVE7JmPbZIcJ1 YMoZvHh0NSjY5D0HZlwtbDO7pDz9sZf1QEOgjH828fhtborkaHaUI46pmrMjiBnY6ujXMcWD pxtikki0zY22nrxfTs5xDWGxyrc/cmucjxClJF6+OYVUSaZhiiHfa9Pr+41okLgsRB0AmNwE f6ItY3TI8DGCBQowggUGAgEBMIGjMIGdMQswCQYDVQQGEwJVUzEQMA4GA1UECBMHRmxvcmlk YTESMBAGA1UEBxMJTmljZXZpbGxlMRkwFwYDVQQKExBDdWRhIFN5c3RlbXMgTExDMRwwGgYD VQQDExNDdWRhIFN5c3RlbXMgTExDIENBMS8wLQYJKoZIhvcNAQkBFiBjdXN0b21lci1zZXJ2 aWNlQGN1ZGFzeXN0ZW1zLm5ldAIBCDAJBgUrDgMCGgUAoIICOzAYBgkqhkiG9w0BCQMxCwYJ KoZIhvcNAQcBMBwGCSqGSIb3DQEJBTEPFw0xNDA0MjkxMjEyMzdaMCMGCSqGSIb3DQEJBDEW BBQwp9TfhrnTEOET4u/ew1aAUeSxdzBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIG0BgkrBgEEAYI3EAQxgaYwgaMwgZ0xCzAJBgNV BAYTAlVTMRAwDgYDVQQIEwdGbG9yaWRhMRIwEAYDVQQHEwlOaWNldmlsbGUxGTAXBgNVBAoT EEN1ZGEgU3lzdGVtcyBMTEMxHDAaBgNVBAMTE0N1ZGEgU3lzdGVtcyBMTEMgQ0ExLzAtBgkq hkiG9w0BCQEWIGN1c3RvbWVyLXNlcnZpY2VAY3VkYXN5c3RlbXMubmV0AgEIMIG2BgsqhkiG 9w0BCRACCzGBpqCBozCBnTELMAkGA1UEBhMCVVMxEDAOBgNVBAgTB0Zsb3JpZGExEjAQBgNV BAcTCU5pY2V2aWxsZTEZMBcGA1UEChMQQ3VkYSBTeXN0ZW1zIExMQzEcMBoGA1UEAxMTQ3Vk YSBTeXN0ZW1zIExMQyBDQTEvMC0GCSqGSIb3DQEJARYgY3VzdG9tZXItc2VydmljZUBjdWRh c3lzdGVtcy5uZXQCAQgwDQYJKoZIhvcNAQEBBQAEggIAG+EIl7hMzqBbxqXEMka/DIcUD2lX UNqFM63EaLk7Ag+QV3xuQaRStZySIPpITq594tpXfyO14YDo9esptwDC9XP+vR1kz745JvRx mgpSQ3hpg1woJ1HySVU/VaU9I0uc/hZPg55zaEY77x2SEwZuanEGv43eAiy6RpajeJijDYd1 wswLSfSGIUsNX6vXS6LC8yBM/zighulmpMgODGwrU7w/COGGh+QlPac3YTifsF4ifmD8yiKU 6hN3koivOheax9OT6xU8682IwGqt3UIx6DQvRK5GdcedLHLpY68ysRtXaDWOUaUfOXeXx1dE +wEJsaDUny+lFhTUsbC2OLfBBlNu8ZbU+QnUMqI762bYh7y6ldn52Q0N4xJPIlxwGbvJKBg3 U2DoGwwh6ZAW9RzsT56TWACuOvwaqqn/NJ2LcBquWvDw9FsWZWwUHE/DZmUFwlwMutGHIX+t 6JyQTUjBrJEKYOQ5HIxt07ljdsq22twKMXMjUS4WgG6w7c+3In0W26sfvjrOV6uEkuBKWk7V iRYWMM6mCSW5VTUouVt66keXcNqYduCQJQhMIXk+hY0GA2kTYAdyVjWRyKd2+EQPxtBg1l7s NVONrCeZ0Hu4xKKC5R2hR0wT7/Jbn7Myg+UfvOoRQxVDBYdlCEGAL7KHu4u9Nf1qThzU26eD sSBlQswAAAAAAAA= --------------ms050909090602050504020304--