HS5 can be configured either via config file, environment variables or command line arguments. The configuration file can be specified via -c command line argument pointing at the configuration file.

Options available in the configuration file:

Use KEY=VALUE format (one option per line). Lines starting with # are treated as comments.

Example:

HTTP_PORT=8085
SERVER_IP=0.0.0.0
DATA_STORAGE_PATH=/var/lib/hs5/data
METADATA_STORAGE_PATH=/var/lib/hs5/meta
LOGLEVEL=info

Option	Type	Default	Description
HTTP_PORT	integer	80	HTTP port HS5 listens on.
SERVER_URL	string	empty	Public/base URL of this server.
DATA_STORAGE_PATH	path	.	Path for HS5 data files.
METADATA_STORAGE_PATH	path	.	Path for HS5 metadata/index files.
SERVER_IP	string	0.0.0.0	Address/hostname HS5 binds to.
INIT_ROOT_ACCESS_KEY	string	root	Initial root access key name on first startup.
INIT_ROOT_PASSWORD	string	auto-generated if unset	Initial root password on first startup.
INIT_CREATE_BUCKET	string	empty	Comma-separated list of buckets to create at startup.
MANUAL_COMMIT	boolean	false	Enable manual commit mode. Accepted true values: true, yes, on, 1.
MANUAL_COMMIT_LIST_CONSISTENT	boolean	true	Keep list operations fully consistent in manual commit mode (higher latency).
COMMIT_AFTER_MS	integer (ms)	30000	In manual commit mode, automatically commit after this delay. Use 0 to disable auto-commit.
WORKER_THREADS	integer	2 x CPU cores	Number of global worker threads.
HTTP_WORKER_THREADS	integer	CPU core count	Number of HTTP worker threads.
LOGLEVEL	enum	info	Log level. Allowed values: debug, info, warn, error.
STOP_ON_ERROR	boolean	false	Stop HS5 on write/read errors instead of continuing.
TRIM_FREESPACE_SIZE	integer (bytes)	1048576	If contiguous free space in the data file exceeds this size, HS5 can punch holes to free disk space. Set to -1 to disable.
DB_MAX_DIRTY_MB	integer (MiB)	50	Maximum LMDB dirty page budget before flush.
WAL_MODE	enum	disabled	Performance WAL mode. Allowed values: disabled, metadata-only, data-only, all-data-only, full, full-all-data.
WAL_PATH	path	metadata path	Path where WAL files are written.
WAL_SMALL_OBJECT_LIMIT	integer (bytes)	6000	In full or data-only WAL mode, object size threshold for writing object data to WAL.
WAL_SIZE_MB	integer (MiB)	1000	WAL file size threshold before reset/rollover.
WAL_ITEMS	integer	10000	WAL item count threshold before reset/rollover.

HS5 can also read these options from environment variables using the HS5_ prefix (for example, HS5_HTTP_PORT). Option precedence is: config file values first, then environment variables, then command line arguments.

Tuning for best performance

• Enable MANUAL_COMMIT for write-heavy workloads when you can tolerate delayed visibility/durability. This reduces commit overhead, but recent writes are not fully durable until commit (or COMMIT_AFTER_MS) runs.
• Set MANUAL_COMMIT_LIST_CONSISTENT=false to reduce list latency in manual commit mode. Trade-off: list results may temporarily miss uncommitted objects (eventual consistency until commit).
• Enable WAL_MODE only when MANUAL_COMMIT is disabled, and prefer placing WAL_PATH on storage that is at least as fast as METADATA_STORAGE_PATH.
• Set TRIM_FREESPACE_SIZE=-1 to disable hole-punch trimming when optimizing for throughput over disk-space reclamation.
• Increase DB_MAX_DIRTY_MB if you have available RAM and want fewer flushes under sustained writes in MANUAL_COMMIT mode.
• Increase WORKER_THREADS above the default when storage is fast and CPU is not saturated; raise gradually while monitoring throughput and p95/p99 latency, since too many threads can increase contention and hurt performance.