On 02/09/2012 03:24 AM, Martin wrote: > 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? >
The metadata buffer size will support size larger than 4K at least, it is on development. > What features other than the trim function does btrfs employ to optimise > for SSD operation? > e.g COW(avoid writing to one place multi-times), delayed allocation(intend to reduce the write frequency) thanks, liubo > > 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 > -- 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
