file/data: wip for storage architectures

lectures/file-and-data-systems/slides.qmd

@@ -90,14 +90,56 @@ author: "Florian Ziemen and Karl-Hermann Wieners"
 * Spools of magnetizable bands
 * Serialized access only
 
-# Finding your data
+# Storage Architectures
 
-KALLE
+> These aren't books in which events of the past are pinned like so many butterflies to a cork. These are the books from which history is derived. There are more than twenty thousand of them; each one is ten feet high, bound in lead, and the letters are so small that they have to be read with a magnifying glass.
+
+from "Small Gods" by Terry Pratchett
+
+## Thou shalt have identifiable data
+
+* There must be a way to reference the data stored on a medium
+* Usual means are (symbolic) names or (numerical) identifiers
+* Must be determined at time of data storage
+* Either implicit, stored with the data or externally
+
+## The more the merrier
+
+* Additional information (metadata) may be needed
+  * Required by the storage architecture
+    * Support optimized data storage or access
+  * Defined by users or applications
+    * Allows indexing of data beyond name or id
+    * Especially for _Content-Adressed Storage_[^1] [(git2 lecture)](/lecture-materials/lectures/git2/slides.html#content-addressable-store)
+
+[^1]: not to be confused with _Content-Adressable Memory_
+
+## File systems (POSIX)
+
+* Data is organized in "Files"
+* Files are grouped in special files, "Directories"
+* File data is stored in fixed size blocks
+* These may not be the same as _device blocks_
+
+## Inodes
+
+* The file's name refers to a metadata table ("inode")
+  * unique numerical identifier
+  * times of state change, permissions
+  * contains actual block locations
+
+## Directories
+
+* Directories map names to inode numbers
+  * More than one name possible ("hard links")
+  * inode's life time managed by "link count"
 
 ## Inodes / blocks / ...
 
 ## Block size
 
+## Fragmentation
+
 
 ## File systems