Overview of FDRINSTANT

FDRINSTANT is an additional cost FDR facility for non-disruptive backup. It works in concert with TimeFinder™, a set of features on EMC Symmetrix DASD subsystems that allow for the “instant” creation of exact duplicates of existing DASD volumes.

FDRINSTANT enhances:

• FDR full volume backup
• FDRDSF data set backup
• FDRCOPY data set copy
• FASTCPK volume reorganization
• FDRABR volume backup (full-volume and incremental backup).

It provides non-disruptive backup of offline operating system DASD volumes, both SMS-managed and non SMS-managed, using technology developed by BMC.

Traditional backups may disrupt normal operations. It obviously takes time to backup a data set or volume. If data sets are being updated by some application while they are being backed up, the backup may not be valid and the data sets may not be usable when they are restored. The usual response to this problem is to quiesce all updates to the data during the backup, disrupting normal operation until the backup is complete.

When used with TimeFinder, FDRINSTANT allows you to instantly create a point-in-time copy of an online DASD volume and easily backup or copy data from that point-in-time copy as if it was coming from the original volume. Updates to the data need to be quiesced only for the few moments necessary to create the point-in-time copy, if at all.

There are three types of TimeFinder support; your Symmetrix subsystems may be licensed for any or all of these features (EMC literature has more details on TimeFinder options):

• TimeFinder/Mirror - Allows the creation of Business Continuance Volumes (BCVs). BCVs are mirrors of standard (online) DASD volumes that can be attached (established) or detached (split) on command. When established, all data tracks are initially copied then updated tracks are mirrored to the BCV, maintaining the BCV as an exact copy of the standard DASD volume. When split, they are a point-in-time image of the volume they were attached to and can be used as the source for backups. TimeFinder/Mirror BCVs are the original Symmetrix point-in-time support and were once just called “TimeFinder”. FDRINSTANT has supported BCVs for many years. EMC refers to TimeFinder/Mirror as the “ultra-performance option”.
• TimeFinder/Clone - Allows the creation of point-in-time images by “Snapping” a full-volume image or a data set from one standard DASD volume within a Symmetrix to another. Although the Snap completes in moments and the snap target can be immediately used as if the copy was complete, the data is actually copied in the background by the Symmetrix control unit. Full-volume Snaps can be used as point-in-time copies for backups, and data set Snaps can be used for instant replication of data sets. EMC refers to TimeFinder/Clone as “ultra-functional, high-performance copies”.
• TimeFinder/Snap - Allows the creation of point-in-time images by “Snapping” a full-volume image from a standard DASD volume to a “virtual DASD” in the same Symmetrix. Virtual DASD are special devices that are not assigned real DASD space; however, there is also a pool of “save disks” associated with the virtual DASD. When you Snap a standard DASD to a virtual DASD, tracks are not immediately copied; but as tracks are updated on the standard DASD, the “before” images of those tracks are saved on a pool disk, so the pool disks can be much smaller than the associated virtual DASD. When an application such as FDRINSTANT reads the virtual DASD, the Symmetrix returns either the saved updated tracks or the original unmodified tracks from the standard DASD, resulting in a point-in-time image of the standard volume. EMC refers to TimeFinder/Snap as “economical space-saving copies” but backup performance takes appreciably more elapsed time that the other options.

All three types of TimeFinder are supported by FDRINSTANT, but the procedures and considerations for each are different, as described in the following sections.

FDRINSTANT supports some additional features of TimeFinder:

• Consistent Split or Snap - (Splitting multiple BCVs or Snapping multiple DASD volumes at the same point-in-time). This requires an additional TimeFinder feature called TimeFinder/CG (Consistency Group). See Consistent Backup Support .

FDRINSTANT enhances FDR components

FDRINSTANT enhances FDR, FDRDSF, FDRCOPY, and FDRABR (Volume Backups) to read from an offline copy of an online volume that was created as a point-in-time image using TimeFinder. This creates a backup or copy of the volumes or data sets that looks exactly like a normal backup or copy, except that the data is frozen in time.

If you are licensed for FDRABR, FDRINSTANT enhances ABR Volume Backups, both full-volume (TYPE=FDR) and incremental (TYPE=ABR/DSF/AUTO) to use TimeFinder, by creating “instant” point-in-time copies of the volumes to be backed up, and then moving that captured data to tape.

FDRINSTANT enhances FDRCOPY

FDRINSTANT also enhances FDRCOPY to improve data set copy performance.

If you have TimeFinder/Clone, EMCSNAP can do “instant” copies of data sets where the copying of the data appears to complete in just a few seconds. The data tracks are actually copied by a background process in the Symmetrix control unit, but EMCSNAP is designed so that you can treat the data as if it was immediately copied. EMCSNAP interacts with TimeFinder/Mirror BCV operations, so the use of EMCSNAP can affect your full-volume and incremental backups that use FDRINSTANT with BCVs (see member EMCSNAP in the FDR Installation Control Library (ICL) for details).

By default, EMCSNAP is enabled. If you prefer to not use EMCSNAP, run FDRZAPOP with the input: ZAP DISABLE=EMCSNAP

FDRCOPY uses EMCSNAP if all the necessary EMCSNAP microcode fixes are installed on your Symmetrix. If you are not using TimeFinder/Mirror/Mirror (BCVs), we recommend that you use EMCSNAP. If you do use BCVs, you may want to disable EMCSNAP.

If enabled, the use of EMCSNAP is automatic. For each data set to be copied, FDRCOPY determines if the source and target volumes are in the same Symmetrix and if the feature is available. If so, it is automatically used. If EMCSNAP cannot be used, normal read/write I/O is used to copy the data.

TimeFinder / Mirror Business Continuance Volumes

Within an EMC Symmetrix subsystem, a given online volume may have one or more “mirrors”. The mirrors are dynamic copies of the online volume, providing protection against DASD hardware failures.

TimeFinder/Mirror enables designated DASD volumes to be used as a special mirror called a Business Continuance Volume or BCV. A given online volume has normal mirrors as well as BCVs, but unlike normal mirrors, a BCV:

• Has its own device address but it must be identified as a BCV in the Symmetrix configuration.
• Is not permanently assigned to any online volume.
• Can be connected (ESTABLISHed) by host software as a BCV mirror of any online volume in the Symmetrix subsystem with the same size and format. While ESTABLISHed, after initial track copying is complete, the BCV is always an exact copy of its online volume.

EMC TimeFinder documentation contains more details on TimeFinder/Mirror and BCVs. EMC provides a utility program, EMCTF, for the management of BCVs; you need to use EMCTF for some FDRINSTANT operations, as explained in this chapter. Examples of EMCTF control statements are shown in this chapter, but you should review the current EMCTF documentation provided by EMC to verify control statement format and options.

TimeFinder/Clone snapped volumes

TimeFinder/Clone allows you to Snap any volume in the Symmetrix to any other volume of the same type (for example, 3390) and same size (or larger). Unlike BCVs, the target volumes do not have to be specially identified in the Symmetrix configuration.

• Snap of a volume executes in just moments, so the creation of the point-in-time volume image appears to be almost instantaneous.
• In fact, Snap creates a Snap session between the source and target DASD volumes that lasts after the Snap request appears to complete, until all tracks are copied.
• Data tracks are copied from the source to the target DASD volume in the background.
• Reads to the target DASD volume are handled so that the data presented is always the data that was present on the source DASD volume at the time that the Snap was issued, allowing FDRINSTANT to treat the target DASD volume as a point-in-time image.
• The first Snap to a target DASD volume copies all tracks from the source DASD volume, but Snap supports a Differential mode, so that subsequent Snaps only need to copy any tracks that have changed since the previous Snap (but the Snap session must remain active to track the changes).
• If you restore or copy data from a Snap target DASD volume (such as an ABR volume or data set restore), Snap is used, if possible, to copy the data back to an online DASD volume.

EMC provides a utility, EMCSNAP, that allows you to Snap volumes or data sets, but it is not used by FDRINSTANT. EMCSNAP is also used with TimeFinder/Snap virtual DASD.

When FDR invokes EMCSNAP, an EMC API is required. EMC modules EMCSAI, EMCQCAPI, and SAICALL must be available in LNKLST or JOBLIB/STEPLIB.

TimeFinder/Snap virtual volumes

TimeFinder/Snap allows you to Snap any standard volume in the Symmetrix to one of a set of “virtual” DASD in the same Symmetrix.

• Virtual DASD have their own device number but they do not occupy any space on the real hard DASD in the Symmetrix.
• When they are not in use, virtual DASD cannot be read.
• Snap of a volume to a virtual DASD executes in just moments, and creates a Snap session between the standard source DASD volume and the virtual target DASD that lasts as long as the virtual DASD is in use.
• The virtual DASD must have exactly the same number of cylinders as the online DASD volume being snapped to it. If you have online DASD volumes of various sizes (such as some 3390-3 and some 3390-9), you must define a sufficient number of virtual DASD of the same sizes.
• Snap does not copy any tracks to the virtual DASD, but when a track is updated on the standard DASD volume, the “preupdate” image of the track is copied to a track in a pool of “save disks” associated with the virtual DASD. There are no fixed locations on the save disks: free tracks are allocated as needed and the Symmetrix keeps track of where every track has been saved.
• When FDRINSTANT reads the virtual DASD, the Symmetrix gets updated tracks from the save disks but reads unmodified tracks from the original standard DASD volume, so it appears as if the virtual DASD is a point-in-time image of the standard DASD volume, from the time of the Snap.
• When FDRINSTANT releases the Snap session, all tracks on the virtual and save disks are released.

TimeFinder without FDRINSTANT

Although TimeFinder can instantly create a point-in-time image of a production DASD volume, traditional backup products cannot directly use the image without additional considerations.

For example, a conventional backup product requires that the image be brought online. Since the operating system does not let you put two volumes with the same volume serial online, its volume serial must be changed.

EMCTF and EMCSNAP provide facilities for re-labeling an image so that it can be put online, but re-labeling a volume invokes additional requirements for SMS-managed volumes, VSAM clusters and cataloged data sets. The data sets on the re-labeled volume appear to be uncataloged, which may cause problems during backup, restore, and reporting unless they are renamed and re-cataloged.

A backup of a re-labeled volume appears to be a backup from the new volume serial, not the original volume serial, so additional procedures are required to document this correspondence (for example, backup of volume “B” is really a backup of volume “A”). Restore procedures must be modified to restore the backups to the correct serial (for example, restore volume “B” back to volume “A” and re-label it as “A”).

EMC also provides a utility to rename and recatalog the data sets on the image. Although this could be used to backup those data sets with a standard backup utility, the installation must now use special restore procedures to restore each data set from its temporary name on the backup to its true name on the online volume. For large numbers of data sets, this could be onerous.

The FDRINSTANT solution

FDRINSTANT allows you to create and use a duplicate BCV or Snapped volume image without changing its volume serial or bringing it online. FDR full volume backup, FDRDSF data set backup, FDRCOPY data set copy, and FDRABR volume backups use FDRINSTANT technology to read the image even while it remains offline. A non-disruptive backup or copy can start as soon as the Snap created. Updates to the online volumes can continue while you create the point-in-time backup or copy of the data.

For FDRABR, FDRINSTANT makes volume backups a two-step process. The first step executes a SNAP statement under FDRABR, to create the image of the selected volumes. The image is actually a valid backup at that point-in-time; you can do a restore from it if full-volume or data set recovery is required. The second step executes a normal FDRABR full-volume or incremental backup of the same volumes, except that ABR reads the offline point-in-time image and move it to a backup on tape. There is no need to identify the device address of the image to ABR; it knows the offline address of any given online volume.

FDRINSTANT also makes FDR or FDRDSF backups and FDRCOPY copies a two-step process.

• For TimeFinder/Mirror, you execute the EMCTF utility to SPLIT the BCVs, then invoke FDRINSTANT for FDR, FDRDSF, and FDRCOPY with standard FDR JCL that points to the online volume but which contains a special data set name that identifies the offline BCV just split from the online volume.
• For TimeFinder/Clone and TimeFinder/Snap, you execute program FDRSNAP, which invokes EMCSNAP to create the offline image, then invoke FDRINSTANT for FDR, FDRDSF, and FDRCOPY with a SNAP= parameter. FDRINSTANT verifies that the snapped image is offline and that its volume serial matches the serial of the online DASD volume. It then reads the image in exactly the same way that it would read the online DASD volume.
• In both cases, FDRINSTANT produces a backup that appears to be a conventional backup of the online volume serial. FDRINSTANT blends its unique offline, high-speed non-disruptive backup together with a traditional restore complete with FDR’s powerful logical file capability.

There are no special considerations for restores from a backup created by FDRINSTANT. You can restore entire volumes or individual data sets from those backups. The target volumes for restore are online volumes. Since the backups created by FDRINSTANT appear to be backups of the online volume, there is no special volume serial or data set name concerns.

FDRCOPY data set copy and move can be used with FDRINSTANT in two ways:

• When FDRCOPY detects that the input and output volume associated with a given data set are in the same Symmetrix, it automatically invokes EMCSNAP (an instant copy) if it is enabled in FDR and available in the Symmetrix. Normal read/write is used if the volumes are not both in the same Symmetrix or EMCSNAP is not available.
• Alternatively, you can use TimeFinder software to freeze an image of the volumes containing the desired data sets, and then use FDRCOPY to create copies of those data sets on other online volumes. This is useful if the target volumes are not in the same Symmetrix as the source volumes, allowing you to capture an instant image of the source data sets and copy them at your leisure.