                          Software           Product            Description   M           ___________________________________________________________________   O           PRODUCT NAME:  Volume Shadowing for OpenVMS, Version 6.2 SPD 27.29.12   G           Note: This is the Software Product Description (SPD) for the  !           following two products:   -           o  Volume Shadowing for OpenVMS VAX   /           o  Volume Shadowing for OpenVMS Alpha   M           Except where specifically noted, the features described in this SPD M           apply to both products. The license and part number information is  J           architecture specific. Please refer to the Ordering Information 2           section of this SPD for further details.             DESCRIPTION   P           Volume Shadowing for OpenVMS is a System Integrated Product (SIP) thatP           runs on the VAX and Alpha families of processors. Volume Shadowing forO           OpenVMS implements a RAID Level 1 storage strategy that provides high N           data availability for disk devices by preventing data loss resultingO           from media deterioration or controller or device failure. It prevents J           storage subsystem component failures from interrupting system or!           application operations.   N           Volume shadowing, sometimes referred to as disk mirroring, maintainsO           redundant copies of data on a collection of disks (one copy per disk) I           called a shadow set. Shadow sets consist of one, two, or three  N           compatible disk volumes that are referred to as shadow set members. K           This duplication of data provides enhanced data availability; if  N           data is recorded on multiple disk volumes, it remains accessible if I           one volume becomes unavailable. Disk read and write operations  N           continue transparently with the remaining members of the shadow set.    M                                         DIGITAL                      May 1995   M                                                                   AE-PY1JC-TE            G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12      O           Because a shadow set is made up of multiple disks containing the same P           data, the Volume Shadowing for OpenVMS software can read data from anyH           member of the shadow set. For each read operation, the Volume L           Shadowing for OpenVMS software determines which disk to read from N           using an algorithm that maximizes performance. Volume Shadowing for K           OpenVMS ensures that disk write operations are duplicated on all  L           shadow set members. For maximum performance, Volume Shadowing for I           OpenVMS ensures that shadow set write operations are issued to  )           shadow set members in parallel.   F           If some data on a shadow set member becomes unreadable, the N           shadowing software can read the data from another available member. K           Additionally, with DIGITAL Storage Architecture (DSA) disks, the  O           member with unreadable data can be repaired by rewriting the data to  P           good, replacement areas provided on each disk. Small Computer Systems L           Interface (SCSI) devices certified by Digital for use with volume M           shadowing support data repair. For other SCSI devices, replacement  4           and repair algorithms are device specific.  O           OpenVMS VAX and Alpha system disks and any Files-11 On-Disk Structure K           2 (ODS-2) data disks that are certified by Digital can be volume  M           shadowed. For more information, refer to the Hardware Requirements             section of this SPD.  J           Volume Shadowing for OpenVMS implements a host-based (phase II) J           approach to shadowing disk devices. Previous versions of Volume H           Shadowing for OpenVMS VAX also implemented a controller-based M           approach to disk shadowing (phase I), which is no longer available             or supported.   M           For the purposes of this document, the term CPU is used to refer to N           a single VAX or Alpha computer, containing one or more processors. AK           CPU can be a standalone system or a member of an OpenVMS Cluster  O           system. Also, in this document, the term OpenVMS Cluster refers to a  J           cluster that may contain a mix of VAX systems and Alpha systems            configured together.            ,                                            2           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12      /           Volume Shadowing for OpenVMS supports M           clusterwide shadowing of Digital SCSI and DSA disk storage systems. 5           Specifically, this implementation supports:   A           o  HSC, HSD, HSF, HSJ, HSZ, and K.SCSI controlled disks   M           o  All DSA and Alpha SCSI adapters and controllers that are locally               connected to a CPU   =           o  RF-series controllers and disks connected to the 8              Digital Storage Systems Interconnect (DSSI)  O           Volume Shadowing also supports OpenVMS MSCP served DSA and Alpha SCSI L           disks located within any supported OpenVMS Cluster configuration. N           Volume Shadowing for OpenVMS allows the shadowing of disks that are P           accessible from the system on which shadowing is installed. An OpenVMSF           system parameter enables shadowing at system initialization.             Characteristics   !           Configuration Overview:   M           Volume Shadowing for OpenVMS requires a minimum of one CPU, a disk  K           controller, and a disk unit that is either DSA compliant or SCSI  N           compliant. Although only one disk is required, there must be two or M           more disks in a shadow set in order to maintain multiple copies of  M           the same data. This protects against failure or deterioration of a             single volume.  O           Using two controllers provides a further guarantee of data availabil- K           ity in the event that a single controller fails. OpenVMS Cluster  G           systems can be configured with multiple CPUs, interconnects,  K           controllers, and disks; the resulting configurations can provide  +           extremely high data availability.               Shadow Set Membership:  M           A shadow set can have one, two, or three members. After the failure O           of one member of a two-member shadow set, the shadow set can continue .           operation with the remaining member.    ,                                            3           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12      N           Shadow set members can be added to or removed from the shadow set at>           any time without affecting system or user operation.  N           A disk can be removed from the shadow set either by operator commandL           or automatically by the shadowing software. An inoperative disk isN           removed from the shadow set automatically; operator intervention is            not required.   P           A disk is added to a shadow set on explicit operator command only. TheN           shadowing software ensures that data on the newly added disk is madeP           consistent with the other member(s) by means of a copy operation. FullK           read and write access to the shadow set continues while the copy  #           operation is in progress.   '           Transparency to the End User:   P           To users and application programs, Volume Shadowing for OpenVMS trans-M           parently combines the physical members of a given shadow set into a L           single virtual disk. The shadow set virtual disk acts as a single O           disk; user or application program modifications are not necessary to  M           propagate write data to all of the members of a shadow set; Volume  O           Shadowing for OpenVMS software propagates the data to all shadow set  P           members automatically. Similarly, user and application read operationsN           to the virtual disk are transparently routed to the optimal physical           shadow set member.  O           Volume Shadowing for OpenVMS is invisible to application programs and M           users. All commands and programming language features that address  L           data on unshadowed disks can be used unchanged to address data on            shadowed disks.              Compatibility   O           Volume Shadowing for OpenVMS Alpha is compatible and can operate with P           Volume Shadowing for OpenVMS VAX. The use of both products in a mixed-I           architecture OpenVMS Cluster (VAX and Alpha machines clustered  O           together) can enable the sharing of data disks between VAX and Alpha             systems.        ,                                            4           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12      I           System disks can be shared among VAX nodes or Alpha nodes in a  O           cluster. A single system disk, however, cannot be shared for booting  O           between VAX and Alpha systems in a cluster since booting is architec-            ture specific.               Configuration Limits  N           Volume Shadowing for OpenVMS supports a maximum of 400 disks in mul-N           timember (2 or 3 member) shadow sets on a single OpenVMS Cluster. AnO           unlimited number of single member shadow sets are allowed on the same J           OpenVMS Cluster. These limits are independent of controller and            device type.  $           Configuration Restrictions  O           Controller-based Volume Shadowing for OpenVMS VAX is no longer avail- P           able. One member of a former phase I shadow set can be mounted to formC           a phase II shadow set, and thus allow access to the data.   M           All members of a given shadow set must have the same disk geometry  L           (same number of sectors, tracks, and cylinders) and have the same L           LBNs (Logical Block Numbers). For example, two RA92s could form a H           shadow set. An RZ28 and an RZ28B could also form a shadow set.  L           Shadow set members cannot have hardware write protection enabled. I           Hardware write protection stops volume shadowing software from  (           maintaining identical volumes.  P           Volume Shadowing for OpenVMS does not support shadow sets mounted with!           the /FOREIGN qualifier.   N           Volume Shadowing for OpenVMS provides support for Digital SCSI disksP           and controllers. It is also possible to use shadowing with third-partyI           SCSI disks that have READL (read long) and WRITEL (write long)  I           commands implemented and that use the OpenVMS SCSI disk driver. P           Features are restricted when SCSI disks that do not support READL and O           WRITEL are shadowed; disk bad-block errors resulting from the use of  O           these disks can cause members to be removed from the shadow set. The  K           OpenVMS Mount utility, by default, does not permit SCSI disks to    ,                                            5           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12      L           become members of a shadow set if they do not implement READL and K           WRITEL. This behavior can be overridden with the MOUNT qualifier  K           /NO_FORCED_ERROR, but to do so places the data on these disks in             jeopardy.                HARDWARE REQUIREMENTS   N           Volume Shadowing for OpenVMS does not depend on specific hardware inL           order to operate. All shadowing functions can be performed on any N           supported CPU. Members of a shadow set can be located on any single E           CPU or anywhere in an OpenVMS Cluster system. There are no  N           restrictions on the location of shadow set members beyond the valid O           disk configurations defined in the OpenVMS Operating System Software  N           Product Description (SPD 25.01.xx) and the OpenVMS Cluster Software -           Product Description (SPD 29.78.xx).   "           Disk Controller Support:  N           Volume Shadowing for OpenVMS supports all disk controllers listed asE           supported in the OpenVMS Operating System Software Product  %           Description (SPD 25.01.xx).              Disk Drive Support:   N           Volume Shadowing for OpenVMS supports all disk drives listed as sup-M           ported in the OpenVMS Operating System Software Product Description H           (SPD 25.01.xx), with the following constraints and exceptions:  E           o  RF35 and RF73 disk devices must use at minimum firmware                version T392F.   E           o  RF36 and RF74 disk devices must use at minimum firmware                version V427P.   I           o  KDM70 controllers must be at minimum microcode revision 4.3.   M           o  RZ disks attached to a local VAX SCSI controller on VAX 4000 and 7              VAX 3000 series systems are not supported.           ,                                            6           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12      %           OpenVMS Cluster Environment   H           Volume Shadowing for OpenVMS is fully supported in an OpenVMS I           Cluster when installed on any valid and licensed configuration. J           Volume Shadowing for OpenVMS allows shadowing of disks that are N           locally connected to the VAX or Alpha system on which this software K           is installed. In addition, Volume Shadowing for OpenVMS allows a  O           user on the OpenVMS system to shadow disks connected to other VAX or  3           Alpha systems within the OpenVMS Cluster.   2           An OpenVMS Cluster quorum disk cannot be           shadowed.   L           For additional information, refer to the OpenVMS Cluster Software -           Product Description (SPD 29.78.xx).              SOFTWARE REQUIREMENTS   J           Volume Shadowing for OpenVMS Version 6.2 is a System Integrated 4           Product that requires OpenVMS Version 6.2.  M           For additional information, and minimum software and firmware revi- M           sions for storage subsystems, refer to the OpenVMS Operating System 6           Software Product Description (SPD 25.01.xx).             OPTIONAL SOFTWARE   P           Optional products that may be useful when running Volume Shadowing for           OpenVMS include:  4           o  OpenVMS Cluster Software (SPD 29.78.xx)  .           o  DECram for OpenVMS (SPD 34.26.xx)             o  VAXsimPLUS   B           o  StorageWorks RAID Software for OpenVMS (SPD 46.49.xx)        ,                                            7           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12                 GROWTH CONSIDERATIONS   O           The minimum hardware and software requirements for any future version I           of this product may be different from the requirements for the             current version.  '           DISTRIBUTION AND INSTALLATION   J           Volume Shadowing for OpenVMS Version 6.2 is a System Integrated O           Product that is distributed and installed with the OpenVMS operating             system Version 6.2.              ORDERING INFORMATION  .           For Volume Shadowing on OpenVMS VAX:  4           o  Software Capacity Licenses: QL-AB2A*-**  4           o  Software Per-Disk Licenses: QL-2A1AA-3B  0           o  Software Documentation: QA-AB2AA-GZ  3           o  Software Product Services: QT-AB2A*-**   0           For Volume Shadowing on OpenVMS Alpha:  4           o  Software Capacity Licenses: QL-2A1A*-**  4           o  Software Per-Disk Licenses: QL-2A1AA-3B  0           o  Software Documentation: QA-AB2AA-GZ  3           o  Software Product Services: QT-2A1A*-**   O           *  Denotes variant fields. For additional information about available P              licenses, services, and media, refer to the appropriate price book.          ,                                            8           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12                 SOFTWARE LICENSING  N           This software is furnished under the licensing provisions of Digital@           Equipment Corporation's Standard Terms and Conditions.  .           License Management Facility Support:  N           Volume Shadowing for OpenVMS supports the OpenVMS License Management           Facility (LMF).   I           Licenses for Volume Shadowing for OpenVMS are sold on either a A'           capacity or a per-disk basis.p  O           A capacity license allows a varying number of disks to be shadowed onnI           a single CPU, up to the maximum specified in the Configuration nO           Limits section. When using a capacity licensing scheme in an OpenVMS oL           Cluster, every CPU in an OpenVMS Cluster that mounts a shadow set K           must have a properly sized Volume Shadowing for OpenVMS capacity d           license installed.  J           Alternatively, licenses are available on a per-disk basis using N           concurrent user licensing. With this type of licensing, one per-diskK           license is required for every disk that may become a member of a  L           shadow set. The per-disk license is attached to a particular disk O           during the MOUNT process. That disk can then be included in a shadow  O           set by any OpenVMS VAX member or OpenVMS Alpha member of the OpenVMS s+           Cluster with access to that disk.n  L           Both methods of licensing can coexist in a single OpenVMS Cluster.  N           For more information about the License Management Facility, refer toD           the OpenVMS Operating System Software Product Description M           (SPD 25.01.xx) or the OpenVMS License Management Utility Manual in a(           the OpenVMS documentation set.  M           For more information about Digital's licensing terms and policies, r,           contact your local Digital office.          ,                                            9           G           Volume Shadowing for OpenVMS, Version 6.2       SPD 27.29.12      #           SOFTWARE PRODUCT SERVICES   L           A variety of service options are available from Digital. For more 9           information, contact your local Digital office.s             SOFTWARE WARRANTYl  L           Warranty for this software product is provided by Digital with theK           purchase of a license for the product as defined in the Software a(           Warranty Addendum of this SPD.  N           The previous information is valid at time of release. Please contactH           your local Digital office for the most up-to-date information.  /            1995 Digital Equipment Corporation.p              All rights reserved.  J           [TM] The DIGITAL logo, DECram, Digital, DSSI, HSC, HSC40, HSC50,E                HSC60, HSC65, HSC70, HSC90, HSC95, KDM, MSCP, OpenVMS,hG                OpenVMS Volume Shadowing, RA, RF, RZ, StorageWorks, VAX,mG                VAXcluster, VAXsimPLUS, and VMScluster are trademarks of -                Digital Equipment Corporation.                                       -                                            10w