Added content to properties of storage systems

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

@@ -16,15 +16,26 @@ author: "Florian Ziemen and Karl-Hermann Wieners"
 # Properties of storage systems
 
 ## Latency
+* How long does it take until we get the first bit of data?
+* Crucial when opening many small files (e.g. starting python)
+* Less crucial when reading one big file start-to end.
+* Largely determined by moving pieces in the storage medium.
 
 ## Continuous read / write
 
-## Random read / write
+* How much data do we get per second when we are reading continuously?
+* Important for reading/writing large blobs of data from/into individual files.
 
-## Caching
+## Random read / write
 
-## Parallel read / write 
+* Mixture of latency and continuous read/write
+* Reading many small files / skipping around in files
 
+## Caching
+* Keeping data *in memory* for frequent re-use.
+* Usually storage media like disks have small caches with better properties.
+* e.g. HDD of 16 TB with a 512 MB of cache.
+* Operating systems also cache read.
 
 # Hardware types and access options