{"id":4020,"date":"2026-01-03T14:21:18","date_gmt":"2026-01-03T12:21:18","guid":{"rendered":"https:\/\/www.openmediavault.org\/?p=4020"},"modified":"2026-01-03T14:21:19","modified_gmt":"2026-01-03T12:21:19","slug":"mdadm-cannot-be-set-as-devname-reason-not-posix-compatible","status":"publish","type":"post","link":"https:\/\/www.openmediavault.org\/?p=4020","title":{"rendered":"mdadm: cannot be set as devname. Reason: Not POSIX compatible"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">If you are also affected by this warning from the MD subsystem, then take a look at this example to see how you can permanently disable this warning.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">With Debian 13, mdadm now enforces POSIX-compliant device names for RAID arrays. Many older RAID arrays (metadata version 1.x) store their name internally in the form <code>hostname:array<\/code> (for example <code>nas:md0<\/code>). While Linux filesystems allow colons in filenames, POSIX standards do not. Debian 13 therefore refuses to use such names when creating block device nodes.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When this happens:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>mdadm<\/code> ignores the stored array name<\/li>\n\n\n\n<li>the RAID is still assembled correctly using its UUID<\/li>\n\n\n\n<li>a warning is printed to explain why the name was skipped<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This is an intentional change aimed at improving portability, scripting safety, and long-term compatibility. The RAID itself is not damaged or misconfigured; only the legacy naming scheme is affected.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The following example shows how a RAID5 based on 3 drives is modified.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>root@omv8box:\/# cat \/proc\/mdstat\nPersonalities : &#91;raid0] &#91;raid1] &#91;raid4] &#91;raid5] &#91;raid6] &#91;raid10]\nmd127 : active (auto-read-only) raid5 vdd&#91;2] vdb&#91;0] vdc&#91;1]\n      2093056 blocks super 1.2 level 5, 512k chunk, algorithm 2 &#91;3\/3] &#91;UUU]\nunused devices: &lt;none>\n\nroot@omv8box:\/# mdadm --detail --scan\nmdadm: Value \"omv8box:0\" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.\nARRAY \/dev\/md\/omv8box:0 metadata=1.2 UUID=6b4e1273:61deb387:90439348:6acaeae0\n\nroot@omv8box:\/# mdadm --stop \/dev\/md127\nmdadm: Value \"omv8box:0\" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.\nmdadm: stopped \/dev\/md127\n\nroot@omv8box:\/# mdadm --assemble --update=name --name=md0 \/dev\/md0 \/dev\/vdb \/dev\/vdc \/dev\/vdd\nmdadm: Value \"omv8box:0\" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.\nmdadm: \/dev\/md0 has been started with 3 drives.\n\nroot@omv8box:\/# mdadm --detail --scan\nmdadm: Value \"omv8box:0\" cannot be set as devname. Reason: Not POSIX compatible. Value ignored.\nARRAY \/dev\/md0 metadata=1.2 UUID=6b4e1273:61deb387:90439348:6acaeae0\n\nroot@omv8box:\/# omv-salt deploy run mdadm\n\nroot@omv8box:\/# mdadm --detail --scan\nARRAY \/dev\/md0 metadata=1.2 UUID=6b4e1273:61deb387:90439348:6acaeae0<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>If you are also affected by this warning from the MD subsystem, then take a look at this example to see how you can permanently disable this warning. With Debian 13, mdadm now enforces POSIX-compliant device names for RAID arrays. Many older RAID arrays (metadata version 1.x) store their name internally in the form hostname:array &#8230; <a title=\"mdadm: cannot be set as devname. Reason: Not POSIX compatible\" class=\"read-more\" href=\"https:\/\/www.openmediavault.org\/?p=4020\" aria-label=\"Read more about mdadm: cannot be set as devname. Reason: Not POSIX compatible\">Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-4020","post","type-post","status-publish","format-standard","hentry","category-common"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.1.1 - aioseo.com -->\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<meta name=\"author\" content=\"volker\"\/>\n\t<link rel=\"canonical\" href=\"https:\/\/www.openmediavault.org\/?p=4020\" \/>\n\t<meta name=\"generator\" content=\"All in One SEO (AIOSEO) 5.0.1.1\" \/>\n\t\t<script type=\"application\/ld+json\" class=\"aioseo-schema\">\n\t\t\t{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.openmediavault.org\\\/?p=4020#article\",\"name\":\"mdadm: cannot be set as devname. 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