On 27 February 2016 at 06:12, Martin K. Petersen <martin.petersen@xxxxxxxxxx> wrote: > > "A MAXIMUM WRITE SAME LENGTH field set to zero indicates that the device > server does not report a limit on the number of logical blocks that it > allows to be unmapped or written in a single WRITE SAME command." > > I.e. that parameter says nothing about whether WRITE SAME is supported > or not. > Fair enough. > > Do you have a particular drive that is causing problems? We could quirk > it or add additional heuristics in addition to the ATA Information VPD. > Nah so far the device never showed any problems. It's actually a SATA/USB adapter with UAS support. In fact it is seemingly coherent to the heuristics: [tom@localhost ~]$ sudo sg_vpd /dev/sdb Supported VPD pages VPD page: Supported VPD pages [sv] Unit serial number [sn] Device identification [di] Block limits (SBC) [bl] [tom@localhost ~]$ sudo sg_vpd -p bl /dev/sdb Block limits VPD page (SBC): Write same non-zero (WSNZ): 0 Maximum compare and write length: 0 blocks Optimal transfer length granularity: 1 blocks Maximum transfer length: 65535 blocks Optimal transfer length: 65535 blocks Maximum prefetch length: 65535 blocks Maximum unmap LBA count: 0 Maximum unmap block descriptor count: 0 Optimal unmap granularity: 0 Unmap granularity alignment valid: 0 Unmap granularity alignment: 0 Maximum write same length: 0x0 blocks Maximum atomic transfer length: 0 Atomic alignment: 0 Atomic transfer length granularity: 0 Maximum atomic transfer length with atomic boundary: 0 Maximum atomic boundary size: 0 Since you've mentioned it, why do we disable write same for all devices with a ATA Information VPD? -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
