<snipped> > > Obviously the root problem here is that the disk > reports a sector size of 512 regardless of wether the > jumper has been set or not, and that zfs therefore > splits writes into 512byte blocks. This forces the > disk to read in the remaining 3.5K of the sector > before writing a 4K block, which I guess is a very > effective sequential-to-random conversion. > > Several threads hint that there should be code in > recent builds to handle 4K drives, but if so then > clearly it does not work out of the box. >
As how I understand, the jumper setting only affects how the drive maps logical sector and physical one (offset or not.) The drive always reports 512 byte per sector, but with offset, drive firmware will map LBA7 at the start of a physical sector thus traditional partition layout starting from LBA63 will be aligned to physical sector boundary. Offsetting in drive firmware helps on read performance because now reading should be aligned. However as long as logical sector size is not the same of physical sector size, read-update-write degradation always happens. Looking from the table description in this document: http://www.wdc.com/en/products/advancedformat/ Jumper setting and WD Align utility only tries to align partition with physical sector, once the partition is created, jump setting won't do any good while utility can move the partition. > Are there any tunable parameters to achieve a logical > block size of 4K? Or should I run down to the local > hardware emporium and get an older replacement while > I still have the chance? I guess not, since the drive just reports it's a 512-byte per sector drive no matter how, that makes 4k-sector aware utils/drivers in osol futile. Ivan. -- This message posted from opensolaris.org _______________________________________________ storage-discuss mailing list storage-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/storage-discuss
