Update fox documentation for SLURM and FS

Reviewed-by: Aleix Roca Nonell <aleix.rocanonell@bsc.es>

web/content/fox/_index.md

@@ -21,17 +21,28 @@ the detailed specifications:
 
 ## Access
 
-To access the machine, request a SLURM session from [hut](/hut) using the `fox`
-partition:
+To access the machine, request a SLURM session from [apex](/apex) using the `fox`
+partition. If you need the machine for performance measurements, use an
+exclusive reservation:
 
-    hut% salloc -p fox
+    apex% salloc -p fox --exclusive
 
-Then connect via ssh:
+Otherwise, specify the CPUs that you need so other users can also use the node
+at the same time:
 
-    hut% ssh fox
+    apex% salloc -p fox -c 8
+
+Then use srun to execute an interactive shell:
+
+    apex% srun --pty $SHELL
     fox%
 
-Follow [these steps](/access) if you don't have access to hut or fox.
+Make sure you get all CPUs you expect:
+
+    fox% grep Cpus_allowed_list /proc/self/status
+    Cpus_allowed_list:	0-191
+
+Follow [these steps](/access) if you don't have access to apex or fox.
 
 ## CUDA
 
@@ -89,9 +100,5 @@ Then just run `nix develop` from the same directory:
 
 The machine has several file systems available.
 
-- `$HOME`: Mounted via NFS across all nodes. It is slow and has low capacity.
-  Don't abuse.
-- `/ceph/home/$USER`: Shared Ceph file system across jungle nodes. Slow but high
-  capacity. Stores three redundant copies of every file.
 - `/nvme{0,1}/$USER`: The two local NVME disks, very fast and large capacity.
 - `/tmp`: tmpfs, fast but not backed by a disk. Will be erased on reboot.