Added image and comments to storage media section.

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

@@ -54,7 +54,9 @@ author: "Florian Ziemen and Karl-Hermann Wieners"
 * e.g. HDD of 16 TB with a 512 MB of cache.
 * Operating systems also cache read.
 
-# Hardware types and access options
+# Hardware types 
+
+![](static/storage-media.jpg)
 
 ## Speed vs cost per space
 
@@ -68,27 +70,32 @@ author: "Florian Ziemen and Karl-Hermann Wieners"
 
 * All figures based on a quick google search in 06/2024
 * RAM needs electricity to keep the data.
-* All but tape usually remain powered.
+* All but tape usually remain powered in an HPC.
 
 ## RAM disk
 
 * Use RAM as if it were a disk
-  * `tmpfs` filesystems on levante (`/dev/shm`)
+  * `tmpfs` filesystems on levante (`/dev/shm`, `/tmp/`)
+* High speed, low volume, lost on reboot.
 
 ## Solid-state disk/flash drives
 
-* Non-volatile electronic medium
-  - keeping state (almost) w/o energy supply
+* Non-volatile electronic medium.
+  - keeping state (almost) without energy supply.
+* High speed, also under random access.
 
 ## Hard disk
 
-* Stacks of magnetic disks with read/write heads
-* Spinning to make every point accessible by heads
+* Stacks of magnetic disks with read/write heads.
+* Spinning to make every point accessible by heads.
+* Basically a stack of modern record players.
+* Good for bigger files, not ideal for random access.
 
 ## Tape
 
 * Spools of magnetizable bands
 * Serialized access only
+* Backup / long-term storage
 
 # Storage Architectures