IT02526: "OPTIMIZING PERFORMANCE" GUIDE DOESN'T PROVIDE INFORMATION ABOUT VIRTUAL MACHINES INSTRUMENTATION TRACE CATEGORIES

IBM Tivoli Storage Manager V7.1 Fix Pack 1 (7.1.1.000) Server Downloads

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
  categories.
  
  The following API categories are included in the instrumentation
  trace report (file named dsminstr.report.xxx), 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
  machines).
  
  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
  interaction.
  - 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
  disks.
  - 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
  platforms
  
  Initial Impact:
  Low
  
  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:
  http://www.ibm.com/support/docview.wss?uid=swg21676872
  
  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

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels