TGTD supports if the client sets these flags, but TGTD does not advertize that FUA/DPO is available. Since TGTD does not do any caching internally but always performs system calls to read/write the underlying data, I do not know if it would be useful to advertize "we support DPO/FUA (but we actually don't do any caching)" This support is communicated via the device specific byte in mode-sense. https://github.com/fujita/tgt/blob/master/usr/sbc.c#L120 We currently signal back to the initiator only if the device is WP (write protected) If you want to have TGTD tell the initiator that FUA/DPO are available we would need to add if (mode6) data[2] |= 0x10; else data[3] |= 0x10; I see no reason to not report DPO/FUA support back to the initiator so I can send a patch to the list later that does this change unless someone objects. regards ronnie sahlberg On Sun, Nov 9, 2014 at 1:12 AM, Xi Tom <xitom900@xxxxxxxxx> wrote: > Hi, > > I am using tgt as iscsi server, and found linux kernel said that a tgt > scsi target does not support DPO and FUA: > > [ 4671.673196] scsi8 : iSCSI Initiator over TCP/IP > [ 4671.928530] scsi 8:0:0:0: RAID IET Controller > 0001 PQ: 0 ANSI: 5 > [ 4671.928800] scsi 8:0:0:0: Attached scsi generic sg5 type 12 > [ 4671.929454] scsi 8:0:0:1: Direct-Access IET VIRTUAL-DISK > 0001 PQ: 0 ANSI: 5 > [ 4671.930878] sd 8:0:0:1: Attached scsi generic sg6 type 0 > [ 4671.932074] sd 8:0:0:1: [sde] 6144000 512-byte logical blocks: > (3.14 GB/2.92 GiB) > [ 4671.932273] sd 8:0:0:1: [sde] Write Protect is off > [ 4671.932277] sd 8:0:0:1: [sde] Mode Sense: 69 00 00 08 > [ 4671.932420] sd 8:0:0:1: [sde] Write cache: enabled, read cache: > enabled, doesn't support DPO or FUA > > > Why does not tgt support these two features ? but I have found its > source code handle > DPO and FUA flag in its bs_rdwr.c. > > Regards, > Tom > -- > To unsubscribe from this list: send the line "unsubscribe stgt" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
