De-indirection for Flash-based SSDs with Nameless Writes

We present Nameless Writes, a new device interface that removes the need for indirection in modern solid-state storage devices (SSDs). Nameless writes allow the device to choose the location of a write; only then is the client informed of the name (i.e., address) where the block now resides. Doing so allows the device to control block-allocation decisions, thus enabling it to execute critical tasks such as garbage collection and wear leveling, while removing the need for large and costly indirection tables. We demonstrate the effectiveness of nameless writes by porting the Linux ext3 file system to use an emulated nameless-writing device and show that doing so both reduces space and time overheads, thus making for simpler, less costly, and higher-performance SSD-based storage.