Memory
The swap file this server falls back on, and how much memory Redis is allowed to use.
Two cards: the swap file, and Redis.
Extra memory (swap)
Swap is disk the kernel uses when real memory runs out. It is far slower than RAM, and that is the point — a server that swaps is slow, where a server that simply runs out of memory starts killing processes, and the process it kills is usually the one you cared about.
Right now reports what exists today: total size and how much of it is in use. Below that, the size choices — Off, 1 GB, 2 GB (marked recommended), 4 GB, or Custom in megabytes.
1–2 GB is enough for most servers. Swap is a safety net, not extra capacity; if your applications genuinely need more memory than the box has, more swap buys you a slower version of the same problem.
The form guards the disk as well as the memory:
- a size using more than half the free disk space is refused outright, with the free space named;
- a size that leaves the disk tight is accepted but warned about — applications and backups need that space too;
- the maximum is 65,536 MB (64 GB).
Turning swap off asks twice
If swap is in use when you turn it off, the panel says exactly how much is in use and what happens next: that memory has to fit in RAM instead, and if it does not, the kernel starts killing processes. Off on a server with nothing in swap is uneventful.
Redis
Redis is installed with the panel and used for its cache, its sessions and its job queue. This card is for the two settings that matter operationally.
Memory limit
Written the way Redis writes it — 256mb, 1gb, or 0 for no limit. The
current usage is shown under the field, so you can size the limit against reality
rather than guessing.
0 is the default. An unlimited Redis on a box with limited memory is a swap
problem waiting to happen, so a limit is worth setting on a small server.
When the limit is reached
The eviction policy. The names are Redis's own:
| Family | Behaviour |
|---|---|
noeviction | Refuse writes once full. Nothing is lost; things start failing. |
allkeys-* | Drop old keys — any key is fair game. |
volatile-* | Drop only keys that have an expiry set. |
For a cache, allkeys-lru is the usual choice. For anything where losing a key
silently would be a bug, noeviction fails loudly instead, which is what you
want.
Password
The current password is shown — masked, with a reveal and a copy button — because
you need it to point your own application or a tool like redis-cli at this
Redis.
- Change sets a new one. The panel updates Redis and its own configuration together, so the two never drift apart.
- Remove password leaves Redis accepting connections without one. Only reasonable when Redis is not reachable from outside this server.
Two states to recognise:
- "A password may be set — the panel could not read the config to tell."
The panel cannot read
redis.conf. Not necessarily broken, just unknown. - "The panel's saved Redis password no longer works — it was changed on the server." Someone changed it outside the panel. Queued jobs, the cache and sessions cannot reach Redis until the two match again; setting a new password here fixes both ends at once.
On an install where the panel cannot rewrite its own configuration file, the
password controls are disabled with that reason, and the change has to be made
on the server with REDIS_PASSWORD updated to match.
Caveats
- Changing swap takes effect immediately — the file is created or removed there and then.
- A Redis password change takes a few seconds to apply; the card says so and offers Check now.
- If Redis is not running, the card says that instead of showing stale numbers.
- Needs Setting · Manage.