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[93.72.151.96]) by smtp.googlemail.com with ESMTPSA id w6sm1415067lfl.14.2019.03.01.02.01.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Mar 2019 02:01:44 -0800 (PST) Subject: Re: zdb question To: Dave Baukus , "freebsd-fs@freebsd.org" References: <7115e017-f9d1-452b-93d7-e2dbcf67618d@spectralogic.com> From: Andriy Gapon Openpgp: preference=signencrypt Autocrypt: addr=avg@FreeBSD.org; prefer-encrypt=mutual; keydata= xsFNBFm4LIgBEADNB/3lT7f15UKeQ52xCFQx/GqHkSxEdVyLFZTmY3KyNPQGBtyvVyBfprJ7 mAeXZWfhat6cKNRAGZcL5EmewdQuUfQfBdYmKjbw3a9GFDsDNuhDA2QwFt8BmkiVMRYyvI7l N0eVzszWCUgdc3qqM6qqcgBaqsVmJluwpvwp4ZBXmch5BgDDDb1MPO8AZ2QZfIQmplkj8Y6Z AiNMknkmgaekIINSJX8IzRzKD5WwMsin70psE8dpL/iBsA2cpJGzWMObVTtCxeDKlBCNqM1i gTXta1ukdUT7JgLEFZk9ceYQQMJJtUwzWu1UHfZn0Fs29HTqawfWPSZVbulbrnu5q55R4PlQ /xURkWQUTyDpqUvb4JK371zhepXiXDwrrpnyyZABm3SFLkk2bHlheeKU6Yql4pcmSVym1AS4 dV8y0oHAfdlSCF6tpOPf2+K9nW1CFA8b/tw4oJBTtfZ1kxXOMdyZU5fiG7xb1qDgpQKgHUX8 7Rd2T1UVLVeuhYlXNw2F+a2ucY+cMoqz3LtpksUiBppJhw099gEXehcN2JbUZ2TueJdt1FdS ztnZmsHUXLxrRBtGwqnFL7GSd6snpGIKuuL305iaOGODbb9c7ne1JqBbkw1wh8ci6vvwGlzx rexzimRaBzJxlkjNfMx8WpCvYebGMydNoeEtkWldtjTNVsUAtQARAQABzR5BbmRyaXkgR2Fw b24gPGF2Z0BGcmVlQlNELm9yZz7CwZQEEwEIAD4WIQS+LEO7ngQnXA4Bjr538m7TUc1yjwUC WbgsiAIbIwUJBaOagAULCQgHAgYVCAkKCwIEFgIDAQIeAQIXgAAKCRB38m7TUc1yj+JAEACV l9AK/nOWAt/9cufV2fRj0hdOqB1aCshtSrwHk/exXsDa4/FkmegxXQGY+3GWX3deIyesbVRL rYdtdK0dqJyT1SBqXK1h3/at9rxr9GQA6KWOxTjUFURsU7ok/6SIlm8uLRPNKO+yq0GDjgaO LzN+xykuBA0FlhQAXJnpZLcVfPJdWv7sSHGedL5ln8P8rxR+XnmsA5TUaaPcbhTB+mG+iKFj GghASDSfGqLWFPBlX/fpXikBDZ1gvOr8nyMY9nXhgfXpq3B6QCRYKPy58ChrZ5weeJZ29b7/ QdEO8NFNWHjSD9meiLdWQaqo9Y7uUxN3wySc/YUZxtS0bhAd8zJdNPsJYG8sXgKjeBQMVGuT eCAJFEYJqbwWvIXMfVWop4+O4xB+z2YE3jAbG/9tB/GSnQdVSj3G8MS80iLS58frnt+RSEw/ psahrfh0dh6SFHttE049xYiC+cM8J27Aaf0i9RflyITq57NuJm+AHJoU9SQUkIF0nc6lfA+o JRiyRlHZHKoRQkIg4aiKaZSWjQYRl5Txl0IZUP1dSWMX4s3XTMurC/pnja45dge/4ESOtJ9R 8XuIWg45Oq6MeIWdjKddGhRj3OohsltKgkEU3eLKYtB6qRTQypHHUawCXz88uYt5e3w4V16H lCpSTZV/EVHnNe45FVBlvK7k7HFfDDkryM7BTQRZuCyIARAAlq0slcsVboY/+IUJdcbEiJRW be9HKVz4SUchq0z9MZPX/0dcnvz/gkyYA+OuM78dNS7Mbby5dTvOqfpLJfCuhaNYOhlE0wY+ 1T6Tf1f4c/uA3U/YiadukQ3+6TJuYGAdRZD5EqYFIkreARTVWg87N9g0fT9BEqLw9lJtEGDY EWUE7L++B8o4uu3LQFEYxcrb4K/WKmgtmFcm77s0IKDrfcX4doV92QTIpLiRxcOmCC/OCYuO jB1oaaqXQzZrCutXRK0L5XN1Y1PYjIrEzHMIXmCDlLYnpFkK+itlXwlE2ZQxkfMruCWdQXye syl2fynAe8hvp7Mms9qU2r2K9EcJiR5N1t1C2/kTKNUhcRv7Yd/vwusK7BqJbhlng5ZgRx0m WxdntU/JLEntz3QBsBsWM9Y9wf2V4tLv6/DuDBta781RsCB/UrU2zNuOEkSixlUiHxw1dccI 6CVlaWkkJBxmHX22GdDFrcjvwMNIbbyfQLuBq6IOh8nvu9vuItup7qemDG3Ms6TVwA7BD3j+ 3fGprtyW8Fd/RR2bW2+LWkMrqHffAr6Y6V3h5kd2G9Q8ZWpEJk+LG6Mk3fhZhmCnHhDu6CwN MeUvxXDVO+fqc3JjFm5OxhmfVeJKrbCEUJyM8ESWLoNHLqjywdZga4Q7P12g8DUQ1mRxYg/L HgZY3zfKOqcAEQEAAcLBfAQYAQgAJhYhBL4sQ7ueBCdcDgGOvnfybtNRzXKPBQJZuCyIAhsM BQkFo5qAAAoJEHfybtNRzXKPBVwQAKfFy9P7N3OsLDMB56A4Kf+ZT+d5cIx0Yiaf4n6w7m3i ImHHHk9FIetI4Xe54a2IXh4Bq5UkAGY0667eIs+Z1Ea6I2i27Sdo7DxGwq09Qnm/Y65ADvXs 3aBvokCcm7FsM1wky395m8xUos1681oV5oxgqeRI8/76qy0hD9WR65UW+HQgZRIcIjSel9vR XDaD2HLGPTTGr7u4v00UeTMs6qvPsa2PJagogrKY8RXdFtXvweQFz78NbXhluwix2Tb9ETPk LIpDrtzV73CaE2aqBG/KrboXT2C67BgFtnk7T7Y7iKq4/XvEdDWscz2wws91BOXuMMd4c/c4 OmGW9m3RBLufFrOag1q5yUS9QbFfyqL6dftJP3Zq/xe+mr7sbWbhPVCQFrH3r26mpmy841ym dwQnNcsbIGiBASBSKksOvIDYKa2Wy8htPmWFTEOPRpFXdGQ27awcjjnB42nngyCK5ukZDHi6 w0qK5DNQQCkiweevCIC6wc3p67jl1EMFY5+z+zdTPb3h7LeVnGqW0qBQl99vVFgzLxchKcl0 R/paSFgwqXCZhAKMuUHncJuynDOP7z5LirUeFI8qsBAJi1rXpQoLJTVcW72swZ42IdPiboqx NbTMiNOiE36GqMcTPfKylCbF45JNX4nF9ElM0E+Y8gi4cizJYBRr2FBJgay0b9Cp Message-ID: <94cf983c-c049-090c-c9ea-76b25e8036b9@FreeBSD.org> Date: Fri, 1 Mar 2019 12:01:43 +0200 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <7115e017-f9d1-452b-93d7-e2dbcf67618d@spectralogic.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 7194F6DFCB X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; spf=pass (mx1.freebsd.org: domain of agapon@gmail.com designates 209.85.208.174 as permitted sender) smtp.mailfrom=agapon@gmail.com X-Spamd-Result: default: False [-4.00 / 15.00]; TO_DN_EQ_ADDR_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip4:209.85.128.0/17]; RCVD_COUNT_THREE(0.00)[3]; MX_GOOD(-0.01)[cached: alt3.gmail-smtp-in.l.google.com]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_HAM_SHORT(-0.72)[-0.720,0]; FORGED_SENDER(0.30)[avg@FreeBSD.org,agapon@gmail.com]; IP_SCORE(-1.27)[ip: (-0.44), ipnet: 209.85.128.0/17(-3.82), asn: 15169(-2.03), country: US(-0.07)]; R_DKIM_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:209.85.128.0/17, country:US]; FROM_NEQ_ENVFROM(0.00)[avg@FreeBSD.org,agapon@gmail.com]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-fs@freebsd.org]; DMARC_NA(0.00)[FreeBSD.org]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[174.208.85.209.list.dnswl.org : 127.0.5.0]; RCVD_TLS_LAST(0.00)[] X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Mar 2019 10:10:04 -0000 On 28/02/2019 15:59, Dave Baukus wrote: > If one uses zdb -R to read the contents of every disk block > associated with the DVA in a raidz2 pool then does one expect the > dump of each DVA to be the exact USER WRITTEN contents of the file ? I think so; on a condition that the DVA refers to the file's data block (L0). > Or does this usage of zdb pull in the raidz2 checksum blocks and/or padding ? > Looking at the code, I don't think so. > > I ask because I have a file of known contents (every byte was written as 0x42 == 'B'), > and if I execute the script below and redirect the output to a file then > the contents of the output file has chunks of non-B characters. > > For example: > > Offset 300000, DVA 1:9f08e2ff000:120000 How did you come up with this DVA? Are you sure about the size component? > Found vdev type: raidz > > 1:9f08e2ff000:120000 >           0 1 2 3 4 5 6 7   8 9 a b c d e f  0123456789abcdef > 010000:  01000321b60d0000  0afb2f931d805100  ....!....Q.../.. > 010010:  02ac211c00020f00  00e2000680110031  .....!..1....... > 010020:  39345f58656c6966  0f001334322e3639  fileX_4996.24... > 010030:  050040cb1f0c0002  02020c003a35352f  .....@../55:.... > 010040:  3822050040ea1f00  210c00020f002136  ...@.."86!.....! > > ----- > > Whereas I expect every DVA chunk to look like: > > Offset 0, DVA 1:9f08e0bf000:120000 > Found vdev type: raidz > > 1:9f08e0bf000:120000 >           0 1 2 3 4 5 6 7   8 9 a b c d e f  0123456789abcdef > 000000:  4242424242424242  4242424242424242  BBBBBBBBBBBBBBBB > 000010:  4242424242424242  4242424242424242  BBBBBBBBBBBBBBBB > 000020:  4242424242424242  4242424242424242  BBBBBBBBBBBBBBBB > 000030:  4242424242424242  4242424242424242  BBBBBBBBBBBBBBBB > 000040:  4242424242424242  4242424242424242  BBBBBBBBBBBBBBBB > > ---- > > On the other hand, if I use a simple program to read the file and verify that every byte > is 0x42 then no errors are reported. > > What gives ? > Am I misusing zdb ? Perhaps. -- Andriy Gapon