NTFS Compression full disk Topic is solved

[rzarco]

I create a ramdisk of 640 MB with NTFS and compression enabled. This disk is used for temporal files and redirect TEMP of Windows (no image file). In normal operation all work ok, but i found a strange behavior.

Only for test, I copy several thousand of small files (43,000 files, 5 folders, average file <2KB, audio content -bad for compression-), but the copy stop several times with error "full disk", if i retry eventually ends. The total size of all files is 135 MB, this is 1/4 of disk size. Even considering the wasted space by the cluster size and MFT reserve there enough space.

If I create a folder with the NTFS compression disabled, the copy end with no problems. Average a little bit more space usage. Something similar happens copying large files (mp3) but less evident.

This behavior may be for the usage of "compact mode" and internal memory organization of ramdisk or is an NTFS strange effect?

Greeting,
RZ

PD. The disk specification is:
Basic settings:
Disk size: 640 MB
Disk type: Direct-IO
Drive letter assigned: T
One-time disk: No
Substance settings:
Memory size: 640 MB
Memory features: IM DMM Compact
Drive file size: 0 MB
Drive file name: -
File system settings:
File system: NTFS
Cluster size: 2048 (this give 327,664 clusters, more the enough for 43K small files).
Volume label: tmp
NTFS compression: Yes
NTFS indexing: No
Create "TEMP" folder: Yes
Image settings:
Enable image file: No

Primo Ramdisk detect 508 MB of Invisible Memory with no problem on using.
Windows 7 System Restore is disabled.

[Support]

I believe this issue is caused by NTFS compression itself, because I reproduce the issue on a real NTFS volume (physical disk). Possible reason is that NTFS consumes lots of overhead space for compression information as there are so many files. Also I think the issue is related to NTFS compression reallocation. Here is a related article I found for your reference.
http://support.microsoft.com/kb/957180

PS. I find that users don't need to do any operations when the "disk full" error dialog pops-up. It seems that Windows will automatically re-arrange the data and handle this issue.

[rzarco]

I appreciate the research and reference. It was odd behavior was not expecting, without major impact on daily life.
Thank you.