My understanding is that for x86 architecture systems, btrfs only allows a sector size of 4kB for a HDD/SSD. That is fine for the present HDDs assuming the partitions are aligned to a 4kB boundary for that device.
However for SSDs... I'm using for example a 60GByte SSD that has: 8kB page size; 16kB logical to physical mapping chunk size; 2MB erase block size; 64MB cache. And the sector size reported to Linux 3.0 is the default 512 bytes! My first thought is to try formatting with a sector size of 16kB to align with the SSD logical mapping chunk size. This is to avoid SSD write amplification. Also, the data transfer performance for that device is near maximum for writes with a blocksize of 16kB and above. Yet, btrfs supports a 4kByte page/sector size only at present... Is there any control possible over the btrfs filesystem structure to map metadata and data structures to the underlying device boundaries? For example to maximise performance, can the data chunks and the data chunk size be aligned to be sympathetic to the SSD logical mapping chunk size and the erase block size? What features other than the trim function does btrfs employ to optimise for SSD operation? Regards, Martin -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html