Module parameters
cetrafs kernel module parameters: defaults, meaning, and which ones are safe in production.
Set at load time, for example in /etc/modprobe.d/cetrafs.conf:
options cetrafs stale_secs=150
Parameters marked writable can also be changed at runtime under /sys/module/cetrafs/parameters/. A change there affects new mounts; for a mount that already exists, use its controls file.
Module parameters are not bounds-checked, because the test suites use them to compress timing. The controls file is bounds-checked; use it to experiment on a live cluster.
Operator parameters
| Parameter | Default | Meaning |
|---|---|---|
stale_secs | 120 | Seconds a peer may be silent before it is treated as dead. The default for every mount. |
hb_interval_secs | 15 | Seconds between heartbeats. The default for every mount. |
auto_defrag | 1 | Background defragmentation, the default for every mount (controls overrides it per mount) |
auto_defrag_min_pct | 200 | Fragmentation threshold: a file’s extent count as a percentage of the minimum for its size |
auto_defrag_min_extents | 4 | Files with fewer extents than this are never auto-defragmented |
scrub | on | Background reclaim of leaked data blocks (marked allocated, referenced by nothing) |
scrub_interval_secs | 1800 | Seconds between scrub cycles |
scrub_gap_secs | 15 | Gap between the scrubber’s two confirming passes. Must be longer than any allocation’s commit window. |
alloc_run_blocks | 256 | Blocks reserved ahead of need for each allocation run (1 MiB). 0 disables it. |
caw_probe | (unset) | Load-time only. A device to probe for compare-and-write capability; the result goes to dmesg and nothing is mounted. |
Internal tuning
Leave these at their defaults unless a developer asks you to change them.
| Parameter | Default | Meaning |
|---|---|---|
bg_sweep_min_secs | 30 | Minimum seconds between refreshes of other nodes’ Block Group descriptors when info or statfs is read |
pf_drain_min_ms | 500 | Minimum milliseconds between on-demand pending-free drains |
Test-only parameters
The module also has fault-injection and test parameters, including cas_selftest, cas_stress, journal_skip_consume, journal_ignore_guard, mount_fail_at, fence_skip_precheck, and parameters whose names start with force_ or nocaw_. Never set these on a production system. Some of them disable the safety checks described in this documentation.
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