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64 lines
1.5 KiB
Markdown
64 lines
1.5 KiB
Markdown
---
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title: "05-filesystems"
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tags:
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- lecture
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- cosc301
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-
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---
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access control models
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- DAC - subject centered
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- MAC - object centered
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- RBAC
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- ACL
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- list of who can do what things to which files
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-
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backups
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devices for file systems
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- device naming conventions under /dev explanation
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- full
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- easy, costly
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- incremental
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- updates only files that have changed
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- level 0, 1, 2, 3, 4, 5 ... 9
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UNIX file system
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- tree 
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- descriptions
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- implementation
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- inode ⇒ data structure documenting data about a file
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structure of directory
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- current working DIR is always in memory
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soft vs hard links
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- hard link must always point to data - to delete a file with hard links you must also delete all the hard links
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- link to _actual inode_
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- soft links can point to a non-existing file
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- link to file _name_
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- can link incompatible file systems e.g., windows, xerox. i.e. fs's that dont use inodes
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advanced file attrs
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special files
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journaling
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- logs changes to journal before writing
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- impact on performance requires data be written twice
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- **question** why not just write a description of the change
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- all or nothing operations: ensure consistency
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-
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creating FS demo
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- `# dd if=/dev/zero of=loopbackfile.img bs=100M count=10 `
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- `# du -sh loopbackfile.img `
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- `# losetup -fP loopbackfile.img `
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- `# losetup –a `
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- `# mkfs.ext4 /root/loopbackfile.img `
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- `# mkdir /loopfs `
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- `# df -hP /loopfs/ `
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- `# mount -o loop /dev/loop0 /loop`
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- `# mount | grep loop`
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