Filesystems 2
Intro / Flashback (04:23)
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Directory entries (03:58)
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FAT directory entries in C (05:02)
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Nested directories (00:46)
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Where is the root directory? (FAT disk header) (05:09)
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FAT: Creating a file (05:02)
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FAT: Deleting files (00:35)
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Exercise: How many entries/clusters? (09:05)
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Stats
- 4 byte fat entries
- 32 byte dir entries
- 2048 byte clusters
1) 200 30 KB files
- Directory cluster can have 64 entries
- Need 4 clusters for directories
- 4 FAT entries
- 30 KB files
- 15 clusters each
- 200 * 15 = 3000 clusters
- 3000 FAT entries
- Total: 3004 clusters/entries
2) Directory of 2000 3KB files
- Directory cluster can have 64 entries
- Need 32 directory clusters
- 32 FAT entries
- Each file needs 2 clusters
- 4000 clusters
- 4000 FAT entries
- Total: 4032 clusters/entries
FAT pros and cons (00:40)
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Hard Drives (02:45)
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Sectors / Cylinders / etc. (01:32)
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Performance / Latency (04:11)
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Sector numbers (01:26)
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OS to disk interface (01:11)
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Hard disks are unreliable (01:12)
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Sector remapping (02:22)
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Disk Scheduling (00:56)
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Minimize seek time (00:00)
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Minimize seek time (02:20)
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SCAN; C-SCAN (01:55)
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Disk scheduling summary (01:38)
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Caching in the Controller (01:36)
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Disk performance and filesystems (01:11)
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Solid state disks (SSD's) (00:46)
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Solid state disks (SSD's) (01:24)
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Flash as disk (01:37)
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Block remapping (07:07)
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SSD Performance (00:41)
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Extra SSD operations (02:00)
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Aside: Future storage (01:06)
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xv6 filesystem (00:34)
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xv6 filesystem (01:14)
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