File systems and network protocols
A file system organises files on a partition. A network protocol carries file operations between devices. ext4 and NTFS are file systems; NFS and SMB/CIFS are network protocols. A NAS may use Btrfs internally and offer the same folder through both SMB and NFS.
Recording disk, data stick or installation stick?
Section titled “Recording disk, data stick or installation stick?”| Purpose | Useful starting point |
|---|---|
| HDD or SSD permanently connected to the receiver for recordings | ext4, if the image supports it for the device. It provides Linux permissions, large files and hardlinks. |
| USB storage for exchanging files with Windows | NTFS or exFAT after checking read/write support on both devices; see the differences below. |
| USB stick for installing an image | The format required by the manufacturer for that flashing procedure, often FAT32. This is a different purpose from recording storage. |
| Recording folder on a NAS | Keep the existing NAS file system and configure a suitable SMB or NFS share. |
Available formats and drivers depend on the image and kernel. Recognising a readable disk does not establish write access or time shift suitability. The receiver’s Device Manager shows which formatting choices it offers. Formatting erases data; switching from SMB to NFS does not require formatting the NAS.
Common formats
Section titled “Common formats”| File system | Features | Meaning for the receiver |
|---|---|---|
| ext4 | Linux permissions, hardlinks, large files and a file system metadata journal. | A good foundation for a permanent local recording disk. Windows does not mount ext4 in Explorer like an ordinary NTFS disk; accessing the receiver’s network share avoids that local format issue. |
| ext3 / ext2 | Older Linux file systems. ext3 has a journal; ext2 does not. | An existing readable disk does not need reformatting solely because its format is older. Back up and check support before making changes. |
| NTFS | Windows file system with large files, journaling, permissions and hardlinks. | Suitable for large exchange files when the Linux driver supports the required writes. Windows permissions and their Linux mapping are not simply identical. |
| exFAT | Large files and widespread exchange support; no journal or hardlinks. | Useful for supported data sticks. The lack of hardlinks is an obstacle for the inspected OpenATV time shift path. |
| FAT32 | Broad device support; each file is limited to 4 GiB minus 1 byte. No journal or hardlinks. | Long recordings may reach the file limit. FAT32 may nevertheless be the correct choice for an installation stick. |
Microsoft documents file sizes, journaling and hardlink support. A journal helps recover file system structure after an interruption. It does not guarantee the full contents of the recording being written or provide a backup against failure or deletion. The usual ext4 mode primarily journals metadata: ext4 journal.
Why 4 GiB can be small for recordings
Section titled “Why 4 GiB can be small for recordings”The FAT32 limit applies per file, not to total share size or free space. At an illustrative 20 Mbit/s, 4 GiB is reached after roughly 29 minutes. Actual channel bitrates vary; do not assume every recording function will split files appropriately. Use a suitable file system without this limit for longer recordings.
XFS, Btrfs and NAS features
Section titled “XFS, Btrfs and NAS features”XFS is a Linux file system with journaling and support for large files and file systems. Btrfs offers features including copy-on-write, checksums and snapshots. The NAS software determines which features are exposed and how they are managed. These are not instructions to rebuild a working NAS for OpenATV. Sources: XFS, Btrfs.
A snapshot preserves an earlier state but may remain on the same storage. Depending on the arrangement, RAID can tolerate a disk failure; it does not generally protect against deletion, malware or loss of the entire NAS. Important data needs an independent backup.
What does OpenATV see over the network?
Section titled “What does OpenATV see over the network?”The receiver sees an NFS or CIFS mount, rather than directly mounting the NAS’s internal file system. A Windows PC therefore does not need an ext4 or Btrfs driver to open that NAS’s SMB share. Conversely, a modern SMB dialect cannot remove the file size limit of an underlying FAT32 disk.
Available operations depend on the complete connection: server file system, share configuration, protocol and client. Even if the NAS file system supports hardlinks, they must work through the share. That actual access is what matters for time shift and NAS recording.
Permissions, mount points and file system checks
Section titled “Permissions, mount points and file system checks”rwdoes not mean “anyone can write”: SMB account permissions, NFS UID/GID mapping or local file permissions still apply. See SMB and NFS.- A mount point is a directory name:
/media/hdddoes not tell you whether the underlying storage is ext4, NTFS or a network share. - UUIDs and labels identify local file systems: Recheck permanent mount point assignments after reformatting.
- Repair belongs on the storage owner: Check a local file system using the appropriate Device Manager after stopping access. Check NAS storage through its own administration tools, not by running local
fsckagainst/media/autofs/....
Verification: These principles were checked against the linked documentation and OpenATV’s path checks. ext4 on the demonstration USB stick was previously tested in practice. No disk was reformatted for this chapter; this does not establish support for every format on every receiver.