1) How will this both work with command recovery that is in Nevada and
doesn't exsist in previous versions of Solaris where it is not?
2) This looks like it expects the tape driver to be the only source of
resets. With MPxIO enabled scsi_vhci can do resets when failing over
paths that would not have originated from the target driver. Some HBA's
also initiate resets on their own.
3) If MPxIO is enabled, the scsi_ifgetcap(9F) would not get the
capability from the HBA and therefor would not do the mode sense/mode
select correctly. See bug 6755363 as this would also effect
SCSI_CAP_TRAN_LAYER_RETRIES.
4) How will this work with ComStar where the transport may not be as
obvious to the target driver.
5) Does TLR give up? If a connection fails in a MPxIO invironment
waiting for a connection to reconnect would prevent failing over. Also
in a non-MPxIO environment not waiting could cause a failure that could
otherwise could be recovered when reconnected.
Randy
Jianfei Wang wrote:
> Hi folks,
> Please review the attached file, it's one page for Transport Layer
> Retries. Thanks.
>
> Best Regards
> Jianfei Wang
>
>
> Template Version: @(#)onepager.txt 1.35 07/11/07 SMI
> Copyright 2007 Sun Microsystems
>
> Sun Proprietary/Confidential: Internal Use Only: Engineering Need-to-Know
>
> 1. Introduction
> 1.1. Project/Component Working Name:
> Solaris storage driver Transport Layer Retries (TLR) support
>
> 1.2. Name of Document Author/Supplier:
> Author: Jianfei Wang
>
> 1.3. Date of This Document:
> 08/05/2009
>
> 1.5. Email Aliases:
> 1.5.1. Responsible Manager:Tzongyu.Lee at Sun.COM
> 1.5.2. Responsible Engineer:Jianfei.Wang at Sun.COM
> 1.5.3. Marketing Manager:
> 1.5.4. Interest List:sas at sun.com
>
> scsi_ifsetcap
>
> 4. Technical Description:
> Background:
> Require support for TLR (Transport Layer Retries) for Sun OEM Tape
> drives
> The Windows and Linux drivers provided by LSI do support TLR. The HP
> LTO SAS drive
> default is TLR disabled. If the HBA driver sees the tape drive
> supports TLR, the
> driver will enable TLR on the HBA and tape driver.
>
>
> 4.1. Details:
> For support Transport Layer Retries(TLR), It would add one scsi
> transport capability.
> It could get TLR capability by scsi_ifgetcap(9F).The target driver
> should check the HBA's
> capability by scsi_ifgetcap(9F) in attach(9E) entry point of target
> driver, if the initiator
> supports TLR, then issue InquiryVPD to get the capability of the tape
> target to check
> whether the target device is able to support TLR. If the target and
> initiator both
> support TLR, The commands packet send from target driver to HBA should
> set a special
> pkg_flag to notify HBA driver set TLR in control bit before
> transportation.
>
> 4.2. Bug/RFE Number(s):
> 6647764
> 4.5. Interfaces:
>
> INTERFACE STABILITY COMMENTS
> SCSI_CAP_TRAN_LAYER_RETRIES evolving SCSI TLR capability
> tran-layer-retries evolving SCSI_CAP_ASCII content
> FLAG_TLR evolving pkg_flag for TLR
> CMD_TLR_OFF evolving pkt_reason for TLR, if
> the I_T_L nexus does not support the TLR,
> command would fail and
> set this pkt_reason to pkt, target driver
> get this reason and
> turn off the TLR control.
>
> 6. Resources and Schedule:
>
>
> 6.4. Product Approval Committee requested information:
> 6.4.1. Consolidation or Component Name:
> 6.4.3. Type of CPT Review and Approval expected:
> FastTrack
>
>
>
