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docs/lectures/osc/15_file_systems1.md

@@ -16,7 +16,7 @@
 >
 > Hard disks are currently about 4 orders of magnitude slower than main memory.
 
-![hard drive diagram](/lectures/osc/assets/a5.png)
+![hard drive diagram](assets/a5.png)
 
 #### Low Level Format
 
@@ -46,18 +46,20 @@ NOTE: disk capacity is reduced due to preamble & ECC
 
 * **Transfer time**: time to transfer the data
 
-![hard drive access times](/lectures/osc/assets/a6.png)
+![hard drive access times](assets/a6.png)
 
 Multiple requests may be happening at the same time (concurrently), so access time may be increased by **queuing time**
 
 In this scenario, dominance of seek time leaves room for **optimisation** by carefully considering the order of read operations.
 
-![hard disk delay](/lectures/osc/assets/a7.png)
+![hard disk delay](assets/a7.png)
 
 The **estimated seek time** (i.e to move the arm from one track to another) is approximated by:
+
 $$
 T_{s} = n \times m + s
 $$
+
 In which $T_{s}$ denotes the estimated seek time, $n$ the **number of tracks** to be crossed, $m$ the **crossing time per track** and $s$ any **additional startup delay**.
 
 > Let us assume a disk that rotates at 3600 rpm
@@ -66,9 +68,11 @@ In which $T_{s}$ denotes the estimated seek time, $n$ the **number of tracks** t
 > * The average **rotational latency** $T_{r}$ is then 8.3 ms
 >
 > Let **b** denote the **number of bytes transferred**, **N** the **number of bytes per track**, and **rpm** the **rotation speed in rotations per minute**, the per track,  the transfer time, $T_{t}$, is then given by:
+>
 > $$
 > T_{t} = \frac b N \times \frac {ms\space per\space minute}{rpm}
 > $$
+>
 > $N$ bytes take 1 revolution => $\frac{60000}{3600}$ ms = $\frac {ms\space per\space minute}{rpm}$
 >
 > $b$ contiguous bytes takes $\frac{b}{N}$ revolutions.
@@ -119,7 +123,7 @@ In a dynamic situation, several I/O requests will be **made over time** that are
 >
 > The total length is: `|11-1|+|1-36|+|36-16|+|16-34|+|34-9|+|9-12|=111`
 >
-> ![FCFS](/lectures/osc/assets/a8.png)
+> ![FCFS](assets/a8.png)
 
 
 
@@ -131,7 +135,7 @@ In a dynamic situation, several I/O requests will be **made over time** that are
 >
 > Total length is: `|11-12|+|12-9|+|9-16|+|16-1|+|1-34|+|34-36|=61`
 >
-> ![SSTF](/lectures/osc/assets/a9.png)
+> ![SSTF](assets/a9.png)
 >
 > Disadvantages:
 >
@@ -148,7 +152,7 @@ In a dynamic situation, several I/O requests will be **made over time** that are
 >
 > Total length: `|11-12|+|12-16|+|16-34|+|34-36|+|36-9|+|9-1|=60`
 >
-> ![scan algorithm](/lectures/osc/assets/b1.png)
+> ![scan algorithm](assets/b1.png)
 >
 > **Disadvantages**:
 >