docs: add more details to -cacheDataPath vmselect flag (#6708)

vmselect will create `./tmp` dir under `cacheDataPath`. If
`cacheDataPath` is set to `/`, vmselect will use `/tmp`.

content under `/tmp` dir might be auto removed based on the OS
behaviour. See:
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5770

- [x] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).

---------

Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: hagen1778 <roman@victoriametrics.com>
This commit is contained in:
Zhu Jiekun 2024-08-13 21:17:43 +08:00 committed by GitHub
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2 changed files with 5 additions and 2 deletions

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@ -43,7 +43,8 @@ var (
useProxyProtocol = flagutil.NewArrayBool("httpListenAddr.useProxyProtocol", "Whether to use proxy protocol for connections accepted at the given -httpListenAddr . "+
"See https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt . "+
"With enabled proxy protocol http server cannot serve regular /metrics endpoint. Use -pushmetrics.url for metrics pushing")
cacheDataPath = flag.String("cacheDataPath", "", "Path to directory for cache files. By default, the cache is not persisted.")
cacheDataPath = flag.String("cacheDataPath", "", "Path to directory for cache files and temporary query results. "+
"By default, the cache won't be persisted, and temporary query results will be placed under /tmp/searchResults. If set, the cache will be persisted under cacheDataPath/rollupResult, and temporary query results will be placed under cacheDataPath/tmp/searchResults.")
maxConcurrentRequests = flag.Int("search.maxConcurrentRequests", getDefaultMaxConcurrentRequests(), "The maximum number of concurrent search requests. "+
"It shouldn't be high, since a single request can saturate all the CPU cores, while many concurrently executed requests may require high amounts of memory. "+
"See also -search.maxQueueDuration and -search.maxMemoryPerQuery")

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@ -56,6 +56,8 @@ It increases cluster availability, and simplifies cluster maintenance as well as
![Cluster Scheme](Cluster-VictoriaMetrics_cluster-scheme.webp)
> Note that `vmselect` despite being stateless still requires some disk space (a few GBs) for temporary caches. Refer to the `-cacheDataPath` command-line flag for more details.
## Multitenancy
VictoriaMetrics cluster supports multiple isolated tenants (aka namespaces).
@ -1308,7 +1310,7 @@ Below is the output for `/path/to/vmselect -help`:
-blockcache.missesBeforeCaching int
The number of cache misses before putting the block into cache. Higher values may reduce indexdb/dataBlocks cache size at the cost of higher CPU and disk read usage (default 2)
-cacheDataPath string
Path to directory for cache files. By default, the cache is not persisted.
Path to directory for cache files and temporary query results. By default, the cache won't be persisted, and temporary query results will be placed under /tmp/searchResults. If set, the cache will be persisted under cacheDataPath/rollupResult, and temporary query results will be placed under cacheDataPath/tmp/searchResults.
-cacheExpireDuration duration
Items are removed from in-memory caches after they aren't accessed for this duration. Lower values may reduce memory usage at the cost of higher CPU usage. See also -prevCacheRemovalPercent (default 30m0s)
-cluster.tls