How much free space required for Oracle Binaries

In the offical documentation, it states 1.9GB free space required for Enterprise/Standard edition installation, and 2.0GB for Custom type installation. But is it enough?

In recent 10gR2 (10.2.0.4) RAC implementation, it shows at least 7.6GB for Database and 2.0GB for Oracle Clusterware.

[oracle@VMXDB03 10.2.0]$ ls |xargs du -sh
7.6G    asm
2.0G    crs
7.6G    db

The top space consumer is patch backup files.

[oracle@VMXDB03 db]$ ls -a .patch_storage|xargs du -sh
5.9G    .patch_storage

[oracle@VMXDB03 .patch_storage]$ ls |xargs du -sh
116M    4693355_Sep_8_2008_04_01_48
111M    5259835_Jan_26_2009_03_10_54
115M    5348308_Oct_9_2008_21_37_51
110M    5747462_Apr_8_2009_16_52_05
110M    5756769_Apr_8_2009_16_52_07
110M    5868257_Jun_5_2008_23_04_30
110M    5879114_Dec_23_2008_21_11_23
110M    5895190_Apr_8_2009_16_52_09
109M    6051177_Apr_8_2009_16_52_10
111M    6052226_Sep_15_2008_02_20_06
2.8M    6079224_Sep_15_2008_03_58_35
109M    6084232_Apr_8_2009_16_52_13
112M    6163771_Jul_30_2008_02_54_13
110M    6200820_Nov_12_2008_06_29_55
109M    6327692_Aug_13_2008_06_40_23
110M    6374297_Apr_8_2009_16_52_03
110M    6455659_Oct_23_2008_04_35_27
109M    6638558_Apr_8_2009_16_52_01
110M    6678845_Jan_9_2009_00_45_07
14M     6679303_Apr_8_2009_16_51_59
110M    6919819_Feb_17_2009_02_57_35
130M    6923450_Apr_8_2009_16_52_19
110M    6972843_Jan_9_2009_00_45_13
110M    7008262_Jan_9_2009_00_45_15
120M    7123643_Jun_26_2008_01_23_32
448K    7155248_Jul_3_2008_02_10_38
348K    7155249_Jul_3_2008_02_10_48
110M    7155250_Jul_3_2008_02_10_51
109M    7155251_Jul_3_2008_02_10_52
110M    7155252_Jul_3_2008_02_10_54
110M    7189447_Jan_9_2009_00_45_16
156K    7197583_Jul_3_2008_02_11_22
110M    7257461_Feb_24_2009_08_55_57
110M    7257770_Jan_12_2009_23_29_55
21M     7272297_Jan_9_2009_00_45_18
111M    7278117_Aug_13_2008_06_35_40
110M    7309458_Apr_8_2009_16_52_21
110M    7340448_Apr_8_2009_16_52_17
109M    7375611_Sep_16_2008_01_15_53
384K    7375613_Sep_16_2008_01_15_57
636K    7375617_Sep_16_2008_01_15_59
112M    7378661_Sep_15_2008_02_14_51
110M    7552067_Nov_16_2008_22_14_33
110M    7606362_Mar_29_2009_22_37_12
3.3M    7609057_Dec_31_2008_04_17_07
109M    7609058_Dec_31_2008_04_15_23
119M    7691766_Jan_9_2009_00_45_09
106M    7715304_Jan_30_2009_06_03_15
104K    7936793_Mar_19_2009_02_45_58
104K    7936993_Mar_25_2009_04_05_16
784K    8227091_Feb_10_2009_04_36_51
118M    8227106_Mar_17_2009_21_25_14
110M    8230457_Feb_11_2009_00_45_48
131M    8287504_Mar_19_2009_03_50_27
232K    8290506_Mar_24_2009_12_34_30
110M    8309587_Mar_24_2009_12_34_32
109M    8309592_Mar_24_2009_12_34_34
720K    8309623_Mar_24_2009_12_34_36
144K    8309632_Mar_24_2009_12_34_37
2.8M    8309637_Mar_24_2009_12_34_45
6.5M    8309639_Mar_24_2009_12_34_42
1.1M    8309642_Mar_24_2009_12_34_40
120M    8340379_Mar_31_2009_22_25_20
110M    8340383_Mar_30_2009_22_42_04
110M    8340387_Apr_1_2009_21_47_43
104K    8344348_Apr_5_2009_23_07_18
112M    8347704_Apr_7_2009_03_46_17
104K    8362683_Apr_8_2009_16_51_57
111M    8373286_Apr_15_2009_03_06_31
6.5M    8534387_Jun_8_2009_20_04_36
6.5M    8568395_Jun_8_2009_20_04_38
1.7M    8568397_Jun_8_2009_20_04_39
172M    8568398_Jun_25_2009_12_05_00
109M    8568402_Jun_8_2009_20_04_44
3.6M    8568404_Jun_8_2009_20_04_46
110M    8568405_Jun_8_2009_20_04_47
4.0K    LatestOPatchSession.properties
37M     NApply
0       patch_free