diff --git a/notes/.obsidian/plugins/obsidian-activity-history/data.json b/notes/.obsidian/plugins/obsidian-activity-history/data.json
index d8e9432..95c05f6 100644
--- a/notes/.obsidian/plugins/obsidian-activity-history/data.json
+++ b/notes/.obsidian/plugins/obsidian-activity-history/data.json
@@ -13,7 +13,7 @@
     {
       "path": "/",
       "date": "2022-06-13",
-      "size": 865835
+      "size": 866703
     }
   ],
   "activityHistory": [
@@ -718,7 +718,7 @@
         },
         {
           "date": "2022-06-13",
-          "value": 5744
+          "value": 6612
         }
       ]
     }
diff --git a/notes/psi/Data Center Tier.md b/notes/psi/Data Center Tier.md
new file mode 100644
index 0000000..d1a7672
--- /dev/null
+++ b/notes/psi/Data Center Tier.md	
@@ -0,0 +1,11 @@
+# Data Center Tier
+| Param                                          | Tier 1                                                 | Tier 2                                             | Tier 3                                                 | Tier 4                                                                   |
+| ---------------------------------------------- | ------------------------------------------------------ | -------------------------------------------------- | ------------------------------------------------------ | ------------------------------------------------------------------------ |
+| Uptime guarantee                               | 99.671%                                                | 99.751%                                            | 99.982%                                                | 99.995%                                                                  |
+| Downtime per year                              | <28.8h                                                 | <22h                                               | <1.6h                                                  | <26.3min                                                                 |
+| Component redundancy                           | None                                                   | Partial power and cooling redundancy (partial N+1) | Full N+1                                               | Fault tolerant (2N or 2N+1)                                              |
+| Concurrently maintainable                      | No                                                     | No                                                 | Partially                                              | Yes                                                                      |
+| Price                                          | $                                                      | \$\$                                               | \$\$\$                                                 | \$\$\$\$                                                                 |
+| Staffing                                       | none                                                   | 1 shift                                            | 1+ shift                                               | 24/7                                                                     |
+| Typical customer                               | Small companies and start-ups with simple requirements | SMBs                                               | Growing and large businesses                           | Government entities and large enterprises                                |
+| The main reason why companies select this tier | The most affordable data center tier                   | Good cost-to-performance                           | A fine line between high performance and affordability | Fault-tolerant facility for high levels of traffic or processing demands |
diff --git a/notes/psi/psi.md b/notes/psi/psi.md
index 3b2f044..119b438 100644
--- a/notes/psi/psi.md
+++ b/notes/psi/psi.md
@@ -8,6 +8,7 @@ imagePrefix: 'data/'
 ```
 %% Zoottelkeeper: Beginning of the autogenerated index file list  %%
 -  [[psi/Adresace|Adresace]]
+-  [[psi/Data Center Tier|Data Center Tier]]
 -  [[psi/Sítě|Sítě]]
 -  [[psi/Switch|Switch]]
 -  [[psi/Základní konfigurace|Základní konfigurace]]