Mounting an ext3 partition using ext4 fs drivers will usually speed-up your filesystem without actually changing the on-disk structures. Therefore it’s possible to revert to the ext3 driver without any problem. This allows you to easily benefit from delayed allocation (delalloc) and multi-block allocation (mballoc).<\/p>\n
Further performance enhancements are possible if you do change the on-disk structure, e.g. by using extents. The downside is that you can’t mount the filesystem any longer with kernel lacking ext4 support and you can’t revert.<\/p>\n
To enable ext4 features on an existing ext3 filesystem, invoke:<\/p>\n
\r\ntune2fs -O extents,uninit_bg,dir_index \/dev\/DEV \r\n<\/pre>\nUnfotunately, features like flex_bg and >16TB fs support can only be enabled at format time<\/strong>1<\/sup><\/a>.<\/p>\n
Your filesystem is now indeed converted to ext4, however, only files that are written after conversion will benefit from ext4 extends. Existing files would have to be rewritten.
e4defrag<\/code> is being developed to take care of this but in now meant for production environments as of now.<\/p>\nA workaround would be to use
chattr<\/code> to rewrite the files using extends. From the archlinux wiki<\/a>:<\/p>\n\r\nfind \/home -xdev -type f -print0 | xargs -0 chattr +e\r\nfind \/home -xdev -type d -print0 | xargs -0 chattr +e\r\n<\/pre>\nIt is being recommended though, “to test this command on a small number of files first, and check if everything is going all right. It may also be useful to check the filesystem after conversion.<\/em>“2<\/sup><\/a>. Please note their warnings about mercurial repositories and hardlinks in general, too.<\/p>\n
[1] <\/a>https:\/\/wiki.archlinux.org\/index.php\/Ext4#Migrating_files_to_extents<\/a>
\n[2] <\/a>https:\/\/ext4.wiki.kernel.org\/index.php\/Ext4_Howto#Converting_an_ext3_filesystem_to_ext4<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Mounting an ext3 partition using ext4 fs drivers will usually speed-up your filesystem without actually changing the on-disk structures. Therefore it’s possible to revert to the ext3 driver without any problem. This allows you to easily benefit from delayed allocation (delalloc) and multi-block allocation (mballoc). Further performance enhancements are possible if you do change the on-disk structure, e.g. by using… Read more »<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[39],"class_list":["post-1024","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-ext4"],"_links":{"self":[{"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=\/wp\/v2\/posts\/1024","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1024"}],"version-history":[{"count":13,"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=\/wp\/v2\/posts\/1024\/revisions"}],"predecessor-version":[{"id":1049,"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=\/wp\/v2\/posts\/1024\/revisions\/1049"}],"wp:attachment":[{"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1024"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1024"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/possiblelossofprecision.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1024"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}