satellite/audit: much stricter audit transfer speed reqs

With MinBytesPerSecond's old value of 128B, we were allowing multiple
hours for transfer of a maximum-size piece (~2MiB) during
reverifications. We do want to be generous until it has been proven that
something needs to be stricter, but we have hit this point. Hours is
much too long.

Instead, this new value of 150kB is still reasonably generous while
limiting transfer time for a full-size piece to around 15s.

In the case of downloading a single share during verification, the
MinDownloadTimeout will apply and allow for minor network hiccups. We
shorten that time here as well, from 5m to 15s. This should allow a much
higher rate of audit completion in the presence of very slow nodes.

Refs: storj/infra#5390
Change-Id: I7402ebd91b2115b379e7671d6b7455d3b0eae1fb

satellite/audit/worker.go

@@ -21,8 +21,8 @@ var Error = errs.Class("audit")
 // Config contains configurable values for audit chore and workers.
 type Config struct {
 	MaxRetriesStatDB   int           `help:"max number of times to attempt updating a statdb batch" default:"3"`
-	MinBytesPerSecond  memory.Size   `help:"the minimum acceptable bytes that storage nodes can transfer per second to the satellite" default:"128B" testDefault:"1.00 KB"`
-	MinDownloadTimeout time.Duration `help:"the minimum duration for downloading a share from storage nodes before timing out" default:"5m0s" testDefault:"5s"`
+	MinBytesPerSecond  memory.Size   `help:"the minimum acceptable bytes that storage nodes can transfer per second to the satellite" default:"150kB" testDefault:"1.00 KB"`
+	MinDownloadTimeout time.Duration `help:"the minimum duration for downloading a share from storage nodes before timing out" default:"15s" testDefault:"5s"`
 	MaxReverifyCount   int           `help:"limit above which we consider an audit is failed" default:"3"`
 
 	ChoreInterval             time.Duration `help:"how often to run the reservoir chore" releaseDefault:"24h" devDefault:"1m" testDefault:"$TESTINTERVAL"`

satellite/satellite-config.yaml.lock

@@ -77,10 +77,10 @@
 # audit.max-reverify-count: 3
 
 # the minimum acceptable bytes that storage nodes can transfer per second to the satellite
-# audit.min-bytes-per-second: 128 B
+# audit.min-bytes-per-second: 150.00 KB
 
 # the minimum duration for downloading a share from storage nodes before timing out
-# audit.min-download-timeout: 5m0s
+# audit.min-download-timeout: 15s
 
 # how often to recheck an empty audit queue
 # audit.queue-interval: 1h0m0s