{"id":100015,"date":"2018-10-19T07:00:00","date_gmt":"2018-10-19T21:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/?p=100015"},"modified":"2019-03-13T00:22:17","modified_gmt":"2019-03-13T07:22:17","slug":"20181019-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20181019-00\/?p=100015","title":{"rendered":"File-extending writes are not always synchronous, which is entirely within the contract"},"content":{"rendered":"<p>I noted some time ago that <a HREF=\"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/20180725-00\/?p=99335\">the current implementation of NTFS forces certain kinds of writes to be synchronous, even when issued asynchronously<\/a>. Note that this is an implementation decision which is not contractual. Formally, the rule is that any asynchronous operation is permitted (but not required) to complete synchronously. <\/p>\n<p>Malcolm Smith points out that <a HREF=\"https:\/\/www.osr.com\/nt-insider\/2015-issue2\/maintaining-valid-data-length\/\">the ReFS file system does not force extending writes to be synchronous<\/a>. Specifically, ReFS version 1 (Windows 8.1, Windows Server 2012 R2) allowed cached writes to the end of a file to complete asynchronously, and ReFS version 2 (Windows 10 version 1607, Windows Server 2016) maintains validity on a per-range basis, so the need to zero out huge chunks of a file disappears completely. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>It is an option but not a requirement.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-100015","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"<p>It is an option but not a requirement.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/100015","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=100015"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/100015\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=100015"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=100015"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=100015"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}