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APAR status

  • Closed as documentation error.

Error description

  • The Optimizing Performance guide shows the table that lists the
    general API client instrumentation categories, but there is no
    information about the virtual machines instrumentation trace
    The following API categories are included in the instrumentation
    trace report (file named, but are not
    documented in case of performance analysis of virtual machine
    backup using Tivoli Storage Manager client and Tivoli Data
    Protection for Virtual Environments.
    VM Snapshot
    - Represents time taken to generate and remove a VM guest
    snapshot with VMware using the VI SDK.
    - Some of this work is done asynchronously (for example:
    snapshot delete).
    VM Send Data
    - Represents time taken to send data to the Tivoli Storage
    Manager server.
    - Usually this activity is occurring in an interleaved fashion
    with the "VM I/O" reads from VMware to fill the buffer we will
    later send.
    - Each call is a buffer send to the Tivoli Storage Manager
    server. This category encapsulates the time for client-side
    dedup processing/encryption as well as the network send.
    - For FULL/IFFULL backups, the buffer is typically filled to 256
    KB prior to send. With INCR/IFINCR backups, less data might be
    in the buffer.
    VM Get Data
    - Represents time taken to receive data from the Tivoli Storage
    Manager server.
    - This can involve fetching control files from the Tivoli
    Storage Manager server during incremental backup.
    - Can also involve buffer receives during VM guest restore which
    will later be written out using "VM I/O" writes to VMware.
    VM Query
    - Represents queries to the Tivoli Storage Manager server
    regarding certain options.
    - Queries conducted to determine if deduplication and/or
    compression are used. Also node filespace queries (for virtual
    VM Query VE
    - Represents query made to VMware to determine changed disk
    areas (blocks) for VM guest disks. Uses the VMware VI SDK to
    determine a set of changed blocks.
    VM Assign
    - Represents Tivoli Storage Manager server group assignment
    using the dsmGroupHandler.
    VM VCM Lock
    - Represents semaphore locking which takes place during VCMLIB
    (Volume Control Manager) API calls.
    - Involves locking for volume control data reads/updates. Block
    control data manipulation, finding megablocks in a volume, etc.
    VM Transaction
    - Represents transaction processing conducted with the Tivoli
    Storage Manager server (start/end).
    VM I/O
    - Represents reading and writing activity done with VMware VM
    guest disks using the Vix Disk Library for VDDK disks.
    - This can involve any of the available transport paths (NBD,
    NBDSSL, SAN, HOTADD) used by the client.
    - Performance can vary depending on whether the disks being
    interacted with were thin or thick provisioned - also: whether
    they were/are lazy zeroed or not.
    - Reading from VMware disks over SAN has proved somewhat slower
    than direct reads from the disks using a raw volume I/O tool.
    - During VM guest backup, reads from VMware (<=256 KB each) are
    usually interleaved with sends to Tivoli Storage Manager from
    the same thread (no double-buffering yet in the code).
    - Represents time reading ctl file from local disk when sending
    it to the Tivoli Storage Manager server during backup.
    VM Control File I/O
    - Represents VM guest CTL file ("control file") I/O and
    - Writing control files during VM guest operations.
    Thread Wait
    - For Tivoli Storage Manager for VE clients, this has been found
    to represent the time it takes to open and close VDDK disks.
    - When you see this category, this means that this thread is
    waiting on the "utility thread" to open or close a VDDK (VM
    guest) disk.
    - With the Tivoli Storage Manager client during multi-session
    backup, there can be multiple threads which are backing up VM
    guests, but only 1 "utility thread" opening and closing guest
    - This is a VMware limitation where the same thread that opens a
    disk has to close it.
    - In the General Availability code, disks are opened/closed one
    at a time by the utility thread, increasing the possibility of
    bottlenecks for a single client instance.
    - The utility thread opens/closes the disks via API calls to the
    VCenter/ESXi host.
    - The open/close time can also include the time taken to mount
    the disk on the client/proxy system.
    Tivoli Storage Manager Versions Affected:
    Tivoli Storage Manager client 6.4.x. and 7.1.x on all supported
    Initial Impact:
    Additional Keywords:
    trace performances doc tuning vm vmware tdp tsm

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All Tivoli Storage Manager server users.                     *
    * PROBLEM DESCRIPTION:                                         *
    * See error description.                                       *
    * RECOMMENDATION:                                              *
    * None                                                         *

Problem conclusion

  • Information about the Tivoli Storage Manager virtual machine
    instrumentation categories are available in Technote 1676872 at:
    The same information will be added to the Tivoli Storage Manager
    Optimizing Performance Guide in the "Virtual machine
    instrumentation categories" topic.
    Affected platforms: AIX, HP-UX, Solaris, Linux, and Windows.

Temporary fix


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Fix information

Applicable component levels

Document information

More support for: Tivoli Storage Manager

Software version: 71W

Reference #: IT02526

Modified date: 16 July 2014