{"id":99,"date":"2013-03-26T18:21:08","date_gmt":"2013-03-26T10:21:08","guid":{"rendered":"http:\/\/www.datarelab.com\/blog\/?p=99"},"modified":"2013-03-26T18:21:08","modified_gmt":"2013-03-26T10:21:08","slug":"ext3%e4%b8%8eext4%e7%9a%84%e4%b8%bb%e8%a6%81%e5%8c%ba%e5%88%ab","status":"publish","type":"post","link":"https:\/\/www.datarelab.com\/blog\/Technical_literature\/99.html","title":{"rendered":"Ext3\u4e0eExt4\u7684\u4e3b\u8981\u533a\u522b"},"content":{"rendered":"

Linux kernel \u81ea 2.6.28 \u5f00\u59cb\u6b63\u5f0f\u652f\u6301\u65b0\u7684\u6587\u4ef6\u7cfb\u7edf Ext4\u3002 Ext4 \u662f Ext3 \u7684\u6539\u8fdb\u7248\uff0c\u4fee\u6539\u4e86 Ext3 \u4e2d\u90e8\u5206\u91cd\u8981\u7684\u6570\u636e\u7ed3\u6784\uff0c\u800c\u4e0d\u4ec5\u4ec5\u50cf Ext3 \u5bf9 Ext2 \u90a3\u6837\uff0c\u53ea\u662f\u589e\u52a0\u4e86\u4e00\u4e2a\u65e5\u5fd7\u529f\u80fd\u800c\u5df2\u3002Ext4 \u53ef\u4ee5\u63d0\u4f9b\u66f4\u4f73\u7684\u6027\u80fd\u548c\u53ef\u9760\u6027\uff0c\u8fd8\u6709\u66f4\u4e3a\u4e30\u5bcc\u7684\u529f\u80fd\uff1a<\/p>\n

1. \u4e0e Ext3 \u517c\u5bb9\u3002<\/strong> \u6267\u884c\u82e5\u5e72\u6761\u547d\u4ee4\uff0c\u5c31\u80fd\u4ece Ext3 \u5728\u7ebf\u8fc1\u79fb\u5230 Ext4\uff0c\u800c\u65e0\u987b\u91cd\u65b0\u683c\u5f0f\u5316\u78c1\u76d8\u6216\u91cd\u65b0\u5b89\u88c5\u7cfb\u7edf\u3002\u539f\u6709 Ext3 \u6570\u636e\u7ed3\u6784\u7167\u6837\u4fdd\u7559\uff0cExt4 \u4f5c\u7528\u4e8e\u65b0\u6570\u636e\uff0c\u5f53\u7136\uff0c\u6574\u4e2a\u6587\u4ef6\u7cfb\u7edf\u56e0\u6b64\u4e5f\u5c31\u83b7\u5f97\u4e86 Ext4 \u6240\u652f\u6301\u7684\u66f4\u5927\u5bb9\u91cf\u3002<\/p>\n

2. \u66f4\u5927\u7684\u6587\u4ef6\u7cfb\u7edf\u548c\u66f4\u5927\u7684\u6587\u4ef6\u3002<\/strong> \u8f83\u4e4b Ext3 \u76ee\u524d\u6240\u652f\u6301\u7684\u6700\u5927 16TB \u6587\u4ef6\u7cfb\u7edf\u548c\u6700\u5927 2TB \u6587\u4ef6\uff0cExt4 \u5206\u522b\u652f\u6301 1EB\uff081,048,576TB\uff0c 1EB=1024PB\uff0c 1PB=1024TB\uff09\u7684\u6587\u4ef6\u7cfb\u7edf\uff0c\u4ee5\u53ca 16TB \u7684\u6587\u4ef6\u3002<\/p>\n

3. \u65e0\u9650\u6570\u91cf\u7684\u5b50\u76ee\u5f55\u3002<\/strong> Ext3 \u76ee\u524d\u53ea\u652f\u6301 32,000 \u4e2a\u5b50\u76ee\u5f55\uff0c\u800c Ext4 \u652f\u6301\u65e0\u9650\u6570\u91cf\u7684\u5b50\u76ee\u5f55\u3002<\/p>\n

4. Extents\u3002<\/strong> Ext3 \u91c7\u7528\u95f4\u63a5\u5757\u6620\u5c04\uff0c\u5f53\u64cd\u4f5c\u5927\u6587\u4ef6\u65f6\uff0c\u6548\u7387\u6781\u5176\u4f4e\u4e0b\u3002\u6bd4\u5982\u4e00\u4e2a 100MB \u5927\u5c0f\u7684\u6587\u4ef6\uff0c\u5728 Ext3 \u4e2d\u8981\u5efa\u7acb 25,600 \u4e2a\u6570\u636e\u5757\uff08\u6bcf\u4e2a\u6570\u636e\u5757\u5927\u5c0f\u4e3a 4KB\uff09\u7684\u6620\u5c04\u8868\u3002\u800c Ext4 \u5f15\u5165\u4e86\u73b0\u4ee3\u6587\u4ef6\u7cfb\u7edf\u4e2d\u6d41\u884c\u7684 extents \u6982\u5ff5\uff0c\u6bcf\u4e2a extent \u4e3a\u4e00\u7ec4\u8fde\u7eed\u7684\u6570\u636e\u5757\uff0c\u4e0a\u8ff0\u6587\u4ef6\u5219\u8868\u793a\u4e3a\u201c\u8be5\u6587\u4ef6\u6570\u636e\u4fdd\u5b58\u5728\u63a5\u4e0b\u6765\u7684 25,600 \u4e2a\u6570\u636e\u5757\u4e2d\u201d\uff0c\u63d0\u9ad8\u4e86\u4e0d\u5c11\u6548\u7387\u3002<\/p>\n

5. \u591a\u5757\u5206\u914d\u3002<\/strong> \u5f53 \u5199\u5165\u6570\u636e\u5230 Ext3 \u6587\u4ef6\u7cfb\u7edf\u4e2d\u65f6\uff0cExt3 \u7684\u6570\u636e\u5757\u5206\u914d\u5668\u6bcf\u6b21\u53ea\u80fd\u5206\u914d\u4e00\u4e2a 4KB \u7684\u5757\uff0c\u5199\u4e00\u4e2a 100MB \u6587\u4ef6\u5c31\u8981\u8c03\u7528 25,600 \u6b21\u6570\u636e\u5757\u5206\u914d\u5668\uff0c\u800c Ext4 \u7684\u591a\u5757\u5206\u914d\u5668\u201cmultiblock allocator\u201d\uff08mballoc\uff09 \u652f\u6301\u4e00\u6b21\u8c03\u7528\u5206\u914d\u591a\u4e2a\u6570\u636e\u5757\u3002<\/p>\n

6. \u5ef6\u8fdf\u5206\u914d\u3002<\/strong> Ext3 \u7684\u6570\u636e\u5757\u5206\u914d\u7b56\u7565\u662f\u5c3d\u5feb\u5206\u914d\uff0c\u800c Ext4 \u548c\u5176\u5b83\u73b0\u4ee3\u6587\u4ef6\u64cd\u4f5c\u7cfb\u7edf\u7684\u7b56\u7565\u662f\u5c3d\u53ef\u80fd\u5730\u5ef6\u8fdf\u5206\u914d\uff0c\u76f4\u5230\u6587\u4ef6\u5728 cache \u4e2d\u5199\u5b8c\u624d\u5f00\u59cb\u5206\u914d\u6570\u636e\u5757\u5e76\u5199\u5165\u78c1\u76d8\uff0c\u8fd9\u6837\u5c31\u80fd\u4f18\u5316\u6574\u4e2a\u6587\u4ef6\u7684\u6570\u636e\u5757\u5206\u914d\uff0c\u4e0e\u524d\u4e24\u79cd\u7279\u6027\u642d\u914d\u8d77\u6765\u53ef\u4ee5\u663e\u8457\u63d0\u5347\u6027\u80fd\u3002<\/p>\n

7. \u5feb\u901f fsck\u3002<\/strong> \u4ee5\u524d\u6267\u884c fsck \u7b2c\u4e00\u6b65\u5c31\u4f1a\u5f88\u6162\uff0c\u56e0\u4e3a\u5b83\u8981\u68c0\u67e5\u6240\u6709\u7684 inode\uff0c\u73b0\u5728 Ext4 \u7ed9\u6bcf\u4e2a\u7ec4\u7684 inode \u8868\u4e2d\u90fd\u6dfb\u52a0\u4e86\u4e00\u4efd\u672a\u4f7f\u7528 inode \u7684\u5217\u8868\uff0c\u4eca\u540e fsck Ext4 \u6587\u4ef6\u7cfb\u7edf\u5c31\u53ef\u4ee5\u8df3\u8fc7\u5b83\u4eec\u800c\u53ea\u53bb\u68c0\u67e5\u90a3\u4e9b\u5728\u7528\u7684 inode \u4e86\u3002<\/p>\n

8. \u65e5\u5fd7\u6821\u9a8c\u3002<\/strong> \u65e5\u5fd7\u662f\u6700\u5e38\u7528\u7684\u90e8\u5206\uff0c\u4e5f\u6781\u6613\u5bfc\u81f4\u78c1\u76d8\u786c\u4ef6\u6545\u969c\uff0c\u800c\u4ece\u635f\u574f\u7684\u65e5\u5fd7\u4e2d\u6062\u590d\u6570\u636e\u4f1a\u5bfc\u81f4\u66f4\u591a\u7684\u6570\u636e\u635f\u574f\u3002Ext4 \u7684\u65e5\u5fd7\u6821\u9a8c\u529f\u80fd\u53ef\u4ee5\u5f88\u65b9\u4fbf\u5730\u5224\u65ad\u65e5\u5fd7\u6570\u636e\u662f\u5426\u635f\u574f\uff0c\u800c\u4e14\u5b83\u5c06 Ext3 \u7684\u4e24\u9636\u6bb5\u65e5\u5fd7\u673a\u5236\u5408\u5e76\u6210\u4e00\u4e2a\u9636\u6bb5\uff0c\u5728\u589e\u52a0\u5b89\u5168\u6027\u7684\u540c\u65f6\u63d0\u9ad8\u4e86\u6027\u80fd\u3002<\/p>\n

9. \u201c\u65e0\u65e5\u5fd7\u201d\uff08No Journaling\uff09\u6a21\u5f0f\u3002<\/strong> \u65e5\u5fd7\u603b\u5f52\u6709\u4e00\u4e9b\u5f00\u9500\uff0cExt4 \u5141\u8bb8\u5173\u95ed\u65e5\u5fd7\uff0c\u4ee5\u4fbf\u67d0\u4e9b\u6709\u7279\u6b8a\u9700\u6c42\u7684\u7528\u6237\u53ef\u4ee5\u501f\u6b64\u63d0\u5347\u6027\u80fd\u3002<\/p>\n

10. \u5728\u7ebf\u788e\u7247\u6574\u7406\u3002<\/strong> \u5c3d\u7ba1\u5ef6\u8fdf\u5206\u914d\u3001\u591a\u5757\u5206\u914d\u548c extents \u80fd\u6709\u6548\u51cf\u5c11\u6587\u4ef6\u7cfb\u7edf\u788e\u7247\uff0c\u4f46\u788e\u7247\u8fd8\u662f\u4e0d\u53ef\u907f\u514d\u4f1a\u4ea7\u751f\u3002Ext4 \u652f\u6301\u5728\u7ebf\u788e\u7247\u6574\u7406\uff0c\u5e76\u5c06\u63d0\u4f9b e4defrag \u5de5\u5177\u8fdb\u884c\u4e2a\u522b\u6587\u4ef6\u6216\u6574\u4e2a\u6587\u4ef6\u7cfb\u7edf\u7684\u788e\u7247\u6574\u7406\u3002<\/p>\n

11. inode \u76f8\u5173\u7279\u6027\u3002<\/strong> Ext4 \u652f\u6301\u66f4\u5927\u7684 inode\uff0c\u8f83\u4e4b Ext3 \u9ed8\u8ba4\u7684 inode \u5927\u5c0f 128 \u5b57\u8282\uff0cExt4 \u4e3a\u4e86\u5728 inode \u4e2d\u5bb9\u7eb3\u66f4\u591a\u7684\u6269\u5c55\u5c5e\u6027\uff08\u5982\u7eb3\u79d2\u65f6\u95f4\u6233\u6216 inode \u7248\u672c\uff09\uff0c\u9ed8\u8ba4 inode \u5927\u5c0f\u4e3a 256 \u5b57\u8282\u3002Ext4 \u8fd8\u652f\u6301\u5feb\u901f\u6269\u5c55\u5c5e\u6027\uff08fast extended attributes\uff09\u548c inode \u4fdd\u7559\uff08inodes reservation\uff09\u3002<\/p>\n

12. \u6301\u4e45\u9884\u5206\u914d\uff08Persistent preallocation\uff09\u3002<\/strong> P2P \u8f6f\u4ef6\u4e3a\u4e86\u4fdd\u8bc1\u4e0b\u8f7d\u6587\u4ef6\u6709\u8db3\u591f\u7684\u7a7a\u95f4\u5b58\u653e\uff0c\u5e38\u5e38\u4f1a\u9884\u5148\u521b\u5efa\u4e00\u4e2a\u4e0e\u6240\u4e0b\u8f7d\u6587\u4ef6\u5927\u5c0f\u76f8\u540c\u7684\u7a7a\u6587\u4ef6\uff0c\u4ee5\u514d\u672a\u6765\u7684\u6570\u5c0f\u65f6\u6216\u6570\u5929\u4e4b\u5185\u78c1\u76d8\u7a7a\u95f4\u4e0d\u8db3\u5bfc\u81f4\u4e0b\u8f7d\u5931\u8d25\u3002 Ext4 \u5728\u6587\u4ef6\u7cfb\u7edf\u5c42\u9762\u5b9e\u73b0\u4e86\u6301\u4e45\u9884\u5206\u914d\u5e76\u63d0\u4f9b\u76f8\u5e94\u7684 API\uff08libc \u4e2d\u7684 posix_fallocate()\uff09\uff0c\u6bd4\u5e94\u7528\u8f6f\u4ef6\u81ea\u5df1\u5b9e\u73b0\u66f4\u6709\u6548\u7387\u3002<\/p>\n

13. \u9ed8\u8ba4\u542f\u7528 barrier\u3002<\/strong> \u78c1 \u76d8\u4e0a\u914d\u6709\u5185\u90e8\u7f13\u5b58\uff0c\u4ee5\u4fbf\u91cd\u65b0\u8c03\u6574\u6279\u91cf\u6570\u636e\u7684\u5199\u64cd\u4f5c\u987a\u5e8f\uff0c\u4f18\u5316\u5199\u5165\u6027\u80fd\uff0c\u56e0\u6b64\u6587\u4ef6\u7cfb\u7edf\u5fc5\u987b\u5728\u65e5\u5fd7\u6570\u636e\u5199\u5165\u78c1\u76d8\u4e4b\u540e\u624d\u80fd\u5199 commit \u8bb0\u5f55\uff0c\u82e5 commit \u8bb0\u5f55\u5199\u5165\u5728\u5148\uff0c\u800c\u65e5\u5fd7\u6709\u53ef\u80fd\u635f\u574f\uff0c\u90a3\u4e48\u5c31\u4f1a\u5f71\u54cd\u6570\u636e\u5b8c\u6574\u6027\u3002Ext4 \u9ed8\u8ba4\u542f\u7528 barrier\uff0c\u53ea\u6709\u5f53 barrier \u4e4b\u524d\u7684\u6570\u636e\u5168\u90e8\u5199\u5165\u78c1\u76d8\uff0c\u624d\u80fd\u5199 barrier \u4e4b\u540e\u7684\u6570\u636e\u3002\uff08\u53ef\u901a\u8fc7 \"mount -o barrier=0\" \u547d\u4ee4\u7981\u7528\u8be5\u7279\u6027\u3002\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"

Linux kernel \u81ea 2.6.28 \u5f00\u59cb\u6b63\u5f0f\u652f\u6301\u65b0\u7684\u6587\u4ef6\u7cfb\u7edf Ext4\u3002 Ext4 \u662f Ext3 \u7684\u6539 […]<\/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":[115,116,14],"class_list":["post-99","post","type-post","status-publish","format-standard","hentry","category-Technical_literature","tag-ext3","tag-ext4","tag-linux"],"views":1557,"_links":{"self":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/posts\/99","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/comments?post=99"}],"version-history":[{"count":0,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/posts\/99\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/media?parent=99"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/categories?post=99"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.datarelab.com\/blog\/wp-json\/wp\/v2\/tags?post=99"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}