Friday, November 24

Tag: hdd

Tables and indexes vs. HDD and SSD

2ndQuadrant, PostgreSQL, Tomas' PlanetPostgreSQL
Although in the future most database servers (particularly those handling OLTP-like workloads) will use a flash-based storage, we're not there yet - flash storage is still considerably more expensive than traditional hard drives, and so many systems use a mix of SSD and HDD drives. That however means we need to decide how to split the database - what should go to the spinning rust (HDD) and what is a good candidate for the flash storage that is more expensive but much better at handling random I/O. There are solutions that try to handle this automatically at the storage level by automatically using SSDs as a cache, automatically keeping the active part of the data on SSD. Storage appliances / SANs often do this internally, there are hybrid SATA/SAS drives with large HDD and small SSD in (more…)