4% is pretty small for a system drive shadow copy. That's what Winsxs is and allows for system restore points. That's not part of system reserved. System reserved area has it's own shadow file(s) to allow repair of the boot sector and some system settings.
You can increase the size of the shadow copy file by changing the system properties. You also can turn it off but you better have another method to restore your system unless you enjoy reloading the OS on every problem.
Added: You don't need a shadow copy on a backup disk. That what the whole disk is for.
You can increase the size of the shadow copy file by changing the system properties. You also can turn it off but you better have another method to restore your system unless you enjoy reloading the OS on every problem.
Added: You don't need a shadow copy on a backup disk. That what the whole disk is for.

Attachments
My Computer
- Computer type
- PC/Desktop
- Computer Manufacturer/Model Number
- Built 2/11/2011
- OS
- Windows 7 Pro-x64
- CPU
- i7-2600 3.4GHz - 3.8GHz Turbo
- Motherboard
- Intel DH67BL-B3
- Memory
- 8Gb - 2x4GB, Muskin 991770 PC3-1333
- Graphics Card(s)
- Integrated Intel HD 2000
- Sound Card
- Integrated Intel 10.1 HD, RealTek ALC892
- Monitor(s) Displays
- Asus LCD VH222H, Haier HL24XSL2a
- Screen Resolution
- 1920x1080, 1920x1080
- Hard Drives
- Crucial SSD C300-128Gb,
Western Digital WD5002AALX - 500Gb,
Western Digital WD7501AALS - 750Gb
- PSU
- Seasonic 650W 80+ Gold Modular
- Case
- Rosewill Defender
- Cooling
- Stock CPU, Four 120mm case fans, PCH fan added
- Keyboard
- Logitech EX100 Y-RBH94 Wireless
- Mouse
- Logitech EX100 M-RCE95 Wireless
- Internet Speed
- 3.0/1.5 Mbs
- Antivirus
- Microsoft Security Essentials
- Browser
- Microsoft Internet Explorer 11
- Other Info
- Antec Veris Premier-Multimedia IR Station,
Cyber Accoustics-3602 Speakers,
AFT XM-5U Card Reader,
Hauppauge TV-HVR-2250,
Sony LX300 USB Turntable