revert: remove access-frequency ILM tiering (#60)

Reverse the first-parent diff of a3df317ae0,
including the feature branch compatibility and mover follow-up fixes.
Retain the independent multi-pool correctness fixes from #178 and migrate
their shared test fixture away from access-tier code.

Tolerate retired ILM keys and XML, read old v9 statistics while writing v8,
and document migration without moving objects or rewriting their metadata.
Include regression coverage using a historical scanner/writer v9 fixture.

Signed-off-by: Feng Ruohang <rh@vonng.com>

internal/config/ilm/help.go

@@ -22,43 +22,10 @@ import "github.com/minio/minio/internal/config"
 const (
 	transitionWorkers = "transition_workers"
 	expirationWorkers = "expiration_workers"
-
-	accessTiering          = "access_tiering"
-	accessPools            = "access_pools"
-	accessMaxSize          = "access_max_size"
-	accessPromoteWatermark = "access_promote_watermark"
-	accessBinWidth         = "access_bin_width"
-	accessBins             = "access_bins"
-	accessFlush            = "access_flush"
-	accessMinResidency     = "access_min_residency"
-	accessWorkers          = "access_workers"
-	accessMaxTracked       = "access_max_tracked"
-
 	// EnvILMTransitionWorkers env variable to configure number of transition workers
 	EnvILMTransitionWorkers = "MINIO_ILM_TRANSITION_WORKERS"
 	// EnvILMExpirationWorkers env variable to configure number of expiration workers
 	EnvILMExpirationWorkers = "MINIO_ILM_EXPIRATION_WORKERS"
-
-	// EnvILMAccessTiering env variable to enable access based tiering
-	EnvILMAccessTiering = "MINIO_ILM_ACCESS_TIERING"
-	// EnvILMAccessPools env variable listing pool indices hottest first
-	EnvILMAccessPools = "MINIO_ILM_ACCESS_POOLS"
-	// EnvILMAccessMaxSize env variable capping bytes held on the hottest pool
-	EnvILMAccessMaxSize = "MINIO_ILM_ACCESS_MAX_SIZE"
-	// EnvILMAccessPromoteWatermark env variable for the hottest pool fill limit
-	EnvILMAccessPromoteWatermark = "MINIO_ILM_ACCESS_PROMOTE_WATERMARK"
-	// EnvILMAccessBinWidth env variable for the access counter resolution
-	EnvILMAccessBinWidth = "MINIO_ILM_ACCESS_BIN_WIDTH"
-	// EnvILMAccessBins env variable for the number of access counter bins
-	EnvILMAccessBins = "MINIO_ILM_ACCESS_BINS"
-	// EnvILMAccessFlush env variable for the counter publish and sweep interval
-	EnvILMAccessFlush = "MINIO_ILM_ACCESS_FLUSH"
-	// EnvILMAccessMinResidency env variable for the anti-thrash floor
-	EnvILMAccessMinResidency = "MINIO_ILM_ACCESS_MIN_RESIDENCY"
-	// EnvILMAccessWorkers env variable to configure number of access tiering workers
-	EnvILMAccessWorkers = "MINIO_ILM_ACCESS_WORKERS"
-	// EnvILMAccessMaxTracked env variable capping tracked objects per node
-	EnvILMAccessMaxTracked = "MINIO_ILM_ACCESS_MAX_TRACKED"
 )
 
 var (
@@ -81,65 +48,5 @@ var (
 			Description: `set the number of expiration workers` + defaultHelpPostfix(expirationWorkers),
 			Optional:    true,
 		},
-		config.HelpKV{
-			Key:         accessTiering,
-			Type:        "on|off",
-			Description: `move objects between fast and slow server pools based on how often they are read` + defaultHelpPostfix(accessTiering),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessPools,
-			Type:        "string",
-			Description: `server pool indices for access tiering, hottest first, e.g. "0,1"` + defaultHelpPostfix(accessPools),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessMaxSize,
-			Type:        "string",
-			Description: `cap total bytes access tiering keeps on the fastest pool, e.g. "2TiB", 0 for unlimited` + defaultHelpPostfix(accessMaxSize),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessPromoteWatermark,
-			Type:        "number",
-			Description: `stop promoting once the fastest pool is this percent full` + defaultHelpPostfix(accessPromoteWatermark),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessBinWidth,
-			Type:        "duration",
-			Description: `resolution of the access counter` + defaultHelpPostfix(accessBinWidth),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessBins,
-			Type:        "number",
-			Description: `number of access counter bins; bins times bin width caps the rule Window` + defaultHelpPostfix(accessBins),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessFlush,
-			Type:        "duration",
-			Description: `how often access counters are published and a promotion sweep runs` + defaultHelpPostfix(accessFlush),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessMinResidency,
-			Type:        "duration",
-			Description: `minimum time an object stays on a pool after access tiering moved it` + defaultHelpPostfix(accessMinResidency),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessWorkers,
-			Type:        "number",
-			Description: `set the number of access tiering workers` + defaultHelpPostfix(accessWorkers),
-			Optional:    true,
-		},
-		config.HelpKV{
-			Key:         accessMaxTracked,
-			Type:        "number",
-			Description: `maximum number of objects each node keeps access counters for` + defaultHelpPostfix(accessMaxTracked),
-			Optional:    true,
-		},
 	}
 )