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Update docs to reflect mount option changes #143

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Update docs to reflect mount option changes #143

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22 changes: 11 additions & 11 deletions Documentation/filesystems/nova.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -71,26 +71,26 @@ After the OS has booted, you can initialize a NOVA instance with the following c
The above commands create a NOVA instance on `/dev/pmem0` and mounts it on
`/mnt/ramdisk`.

Nova support several module command line options:
Nova supports several module command line options:

* metadata_csum: Enable metadata replication and checksums (default 0)

* data_csum: Compute checksums on file data. (default: 0)

* data_parity: Compute parity for file data. (default: 0)

* inplace_data_updates: Update data in place rather than with COW (default: 0)
Nova also supports the following mount options:

* data_cow: Update data with COW rather than in place.

* wprotect: Make PMEM unwritable and then use CR0.WP to enable writes as
needed (default: 0). You must also install the nd_pmem module as with
wprotect =1 (e.g., modprobe nd_pmem readonly=1).
needed. You must also install the nd_pmem module as with wprotect = 1
(e.g., modprobe nd_pmem readonly=1).

For instance to enable all Nova's data protection features:

# modprobe nova metadata_csum=1\
data_csum=1\
data_parity=1\
wprotect=1
# modprobe nova metadata_csum=1 data_csum=1 data_parity=1
# mount -t NOVA -o init -o data_cow -o wprotect /dev/pmem0 /mnt/ramdisk

Currently, remounting file systems with different combinations of options may
not work.
Expand Down Expand Up @@ -547,9 +547,9 @@ and 'data_checksum=0'). Without parity, Nova can detect but not recover from
data corruption. Without checksums, Nova will still detect and recover from
media errors, but not scribbles.

Nova also supports in-place file updates (option: inplace_data_updates=1).
This breaks atomicity for writes, but improve performance, especially for
sub-page writes, since these require a full page COW in the default mode.
Nova uses in-place file updates by default. This breaks atomicity for writes,
but improve performance, especially for sub-page writes, since these require a
full page COW. CoW can be enabled with the mount option 'data_cow'.

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