When storing huge files under NTFS compression, ensure you have twice the disk space
Posted by jpluimers on 2020/01/31
When copying over a 400 gigabyte file over the network to an NTFS compressed folder on a drive with having 600 gigabytes free space, the volume became full after copying ~350 gigabytes.
What I learned is that compressing huge files for later read-only access is fine, but you need about twice the disk space while the copy operation is in progress.
For non-compressed files you can go without this extra reservation.
Background information:
- [WayBack] windows – Why does NTFS compression take up a lot of space? – Super User
- [Archive.is] Understanding NTFS Compression – Ntdebugging Blog
Note there are also issues with NTFS compression and de-duplication. I’m not sure about sparse files. Be careful when you try to compress the system drive where your Windows OS lives on:
- [Archive.is] windows – NTFS compression ate all disk space with no possibility to recover – Super User
- [Archive.is] Shrinking the gap: carving NTFS-compressed files | ForensicFocus.com
–jeroen
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