Below code is doing this when we start a cluster.
Code:
private static void bootstrap(final Path rd, final Configuration c)
throws IOException {
LOG.info("BOOTSTRAP: creating ROOT and first META regions");
try {
// Bootstrapping, make sure blockcache is off. Else, one will be
// created here in bootstap and it'll need to be cleaned up. Better to
// not make it in first place. Turn off block caching for bootstrap.
// Enable after.
HRegionInfo rootHRI = new HRegionInfo(HRegionInfo.ROOT_REGIONINFO);
setInfoFamilyCaching(rootHRI, false);
HRegionInfo metaHRI = new HRegionInfo(HRegionInfo.FIRST_META_REGIONINFO);
setInfoFamilyCaching(metaHRI, false);
HRegion root = HRegion.createHRegion(rootHRI, rd, c);
HRegion meta = HRegion.createHRegion(metaHRI, rd, c);
setInfoFamilyCaching(rootHRI, true);
setInfoFamilyCaching(metaHRI, true);
I found “IN_MEMORY => 'false', BLOCKCACHE => 'false'” in hdfs system.
.META.,,1.META.[1]IS_ROOTfalseIS_META
________________________________
true
________________________________
info
BLOOMFILTER
________________________________
NONEREPLICATION_SCOPE0
COMPRESSION
________________________________
NONEVERSIONS[1]10
________________________________
TTL
2147483647 BLOCKSIZE
________________________________
8192 IN_MEMORYfalse
BLOCKCACHEfalseK��
REGION => {NAME => '.META.,,1', STARTKEY => '', ENDKEY => '', ENCODED =>
1028785192, TABLE => {{NAME => '.META.', IS_META => 'true', FAMILIES => [{NAME
=> 'info', BLOOMFILTER => 'NONE', REPLICATION_SCOPE => '0', COMPRESSION =>
'NONE', VERSIONS => '10', TTL => '2147483647', BLOCKSIZE => '8192', IN_MEMORY
=> 'false', BLOCKCACHE => 'false'}]}}
