HBase 90.4, problems with I/O we had a very heavy read load on top of a write load, write load bursting 14,000 TX per second, and an average of 8,000 per second - each record around 2k.

Because of the I/O the WAL had to be turned off, this introduced problems when Region Servers occasionally died. Implementation of large regions 10GB, and fairly large HBlocks 512MB, increasing flush sizes to reduce minor compactions. Use of MSLAB to virtually eliminate GC all together, use of large heap 12GB on RS.

Worst problems we experienced was META corruption, that really , really sucked.