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Avoiding contention for server resources during clientAvoiding
contention for server resources during clientbackup or
archive.backup or archive.
Technote (FAQ)
QuestionI notice that there are times when my client backups run
slowly and have difficulty finishing in the allotted window. If I
monitor the serverconsole during these times I can see that the
server is busy as well. It seems that the server processes might be
using resources that
the client backup needs. What are the best practices to avoid
contention for these resources during client backup?
Answer
During client backup, archive, or HSM migration sessions the
Tivoli Storage Manager requires many resources to perform these
actions. Resources include database logs, server locks, drives,
mount points or volumes. For example, a client backup session
might
need a mount point, tape drive, and tape volume on which to
store the data. After the session acquires these resources, another
client
session might start that needs to restore data that resides on
the tape volume. The client restore session starts, must wait until
the first
session has unmounted the volume and released it, delaying the
restore session.
The same resources might also be needed by server processes such
as migration, reclamation, expiration, storage pool backup, and
beginning with Tivoli Storage Manager V6.1,
duplicate-identification processes. Anytime a server process starts
and acquires resources
needed to complete its task, those resources are unavailable to
other server processes or client sessions. As a result, contention
for
resources that has a direct affect on performance and the
ability to complete the operation in a timely manner.
Resource contention has a direct effect on performance and the
ability to complete an operation in a timely manner. The problem
of
resource contention is more critical with long-running client
sessions or server processes. Long-running sessions or processes
handle
data under the control of a transaction that prepares database
entries for committing. New database entries are stored in the
recovery
log until they are committed to the database. Long-running
sessions or processes can insert many of these entries under a
single
transaction pinning the recovery log. A pinned recovery log
prevents all transactions from applying database changes and
causes
server processes to run slowly.
The following example shows how to schedule client sessions and
server processes at different times to avoid resource contention
and
delays. The example omits some general setup steps to better
focus on key task. The example uses a particular order for the
server
processes. However, you can reorder the processes to better fit
your environment.
Important: When setting up schedules, try to prevent some server
processes from launching automatically. For example, disable
expiration, migration, reclamation, and duplicate-identification
so that they can be scheduled later. Try using
administrator-commandschedules to run expiration daily.
Disabling expiration, migration, reclamation, and identify
duplicates so they can be scheduled
When setting up schedules, it is better to prevent the automatic
launching of some server processes. Expiration can be set up to run
on
a schedule using administrator command schedules and run daily.
Perform the following steps in order to:
1. Disable automatic expiration with this command:
setopt expinterval 0
2. Disable automatic migration and reclamation processes by
defining storage pools with commands like the following. Note
that
increasing the number of allowed processes for migration and
reclamation might be needed in order for them to complete in a
reasonable amount of time. The actual number of processes
depends on available tape drives. If you already have storage
pools
defined, all of the parameters can be changed using the UPDATE
STGPOOL command.
def devc LARGEFILE devt=file mountlimit=150 mxcap=20480m
dir=/tsmfiledef stg FILEPOOL LARGEFILE maxscratch=200 reclaim=100
hi=100 lo=0 migpr=4 reclaimpr=4 next=tapepool
Setting reclaim=100 disables automatic reclamation while setting
hi=100 disables automatic migration.
3. For Tivoli Storage Manager V6.1.0 and above, if you have
storage pools defined with deduplication enabled, you will also
want to
disable the Identify Duplicates processes:
def stg FILEPOOL LARGEFILE maxscratch=200 reclaim=100 hi=100
lo=0 dedup=yes identifypr=0 migpr=4reclaimpr=4
Setting up the client backup window
Next let's setup the client backup window. This example
initiates an incremental backup of all associated nodes in the
STANDARD
domain. The window starts daily at 8:00PM and assumes
server-prompted scheduling mode . Note that the long running
schedules
continue running past the duration, so a shorter duration may be
need to force long running schedules to start close to the
beginning of
the start-up window.
def schedule standard nightly_backups description="Nightly
backups of nodes in domain standard"starttime=20:00 duration=5
durunits=hours period=1 perunits=days
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Setting up the server maintenance schedules
Now, schedule the server maintenance operations to run outside
of the client backup window, with as little overlap as possible.
The
control of the timing of these schedules is made possible with
the scheduled start time in combination with the duration specified
with
the command. Here's the schedule we are going to establish:
08:00 to end - storage pool backup
11:00 to 13:00 - identify duplicates processes
13:00 to 15:00 - expiration
14:00 to 16:00 - storage pool migration
16:00 to 18:00 - reclamation
18:00 to end - database backup (includes volume history and
device configuration backup)
20:00 to end - client backup
1. Storage Pool Backup
/*--------------------------------------*//* Storage Pool Backup
*//*--------------------------------------*/def script STGBACKUP
"/* Run stg pool backups */"upd script STGBACKUP "backup stg
archivepool copypool maxproc=4 wait=yes" line=005upd script
STGBACKUP "backup stg backuppool copypool maxproc=4 wait=yes"
line=010upd script STGBACKUP "backup stg filepool copypool
maxproc=4 wait=yes" line=020upd script STGBACKUP "backup stg
filepool2 copypool maxproc=4 wait=yes" line=025upd script STGBACKUP
"backup stg tapepool copypool maxproc=3 wait=yes" line=030def sched
STGBACKUP type=admin cmd="run STGBACKUP" active=yes desc="Run all
stg pool backups." \startdate=today starttime=08:00:00 dur=45
duru=minutes per=1 peru=daycommit
2. Identify Duplicates (Tivoli Storage Manager V6.1.0 and
above)
/*--------------------------------------*//* Deduplication
*//*--------------------------------------*/
def script DEDUP "/* Run identify duplicate processes. */"upd
script DEDUP "identify duplicates FILEPOOL numpr=4 duration=120" \
line=010upd script DEDUP "identify duplicates FILEPOOL2 numpr=2
duration=120" \line=015def sched DEDUP type=admin cmd="run DEDUP"
active=yes desc="Run identify duplicates." \startdate=today
starttime=11:00:00 dur=45 duru=minutes per=1 peru=daycommit
3. Expiration
/*--------------------------------------*//*
Expiration/*--------------------------------------*/def script
EXPIRE "/* Run expiration processes. */"upd script EXPIRE "expire
inventory wait=yes duration=120" line=010def sched EXPIRATION
type=admin cmd="run expire" active=yes desc="Run expiration."
\startdate=today starttime=13:00:00 dur=45 duru=minutes per=1
peru=day
commit
4. Migration
/*--------------------------------------*//* Storage Pool
Migration *//*--------------------------------------*/
def script MIGRATE "/* Run stg pool migration */"upd script
MIGRATE "migrate stg archivepool duration=30 wait=yes" line=005upd
script MIGRATE "migrate stg backuppool duration=30 wait=yes"
line=010upd script MIGRATE "migrate stg filepool2 duration=60
wait=yes" line=015def sched MIGRATE type=admin cmd="run MIGRATE"
active=yes desc="Migrate data to tape pools ." \startdate=today
starttime=14:00 dur=45 duru=minutes per=1 peru=day
commit
5. Reclamation
/*--------------------------------------*//* Storage Pool
Reclamation *//*--------------------------------------*/
def script RECLAIM "/* Run stg pool reclamation */"upd script
RECLAIM "reclaim stg filepool threshold=40 duration=120 wait=yes"
line=005upd script RECLAIM "reclaim stg filepool2 threshold=40
duration=120 wait=yes" line=008upd script RECLAIM "reclaim stg
tapepool threshold=60 duration=60 wait=yes" line=010def sched
RECLAIM type=admin cmd="run RECLAIM" active=yes desc="Reclaim space
from FILEPOOL andTAPEPOOL." \startdate=today starttime=16:00 dur=45
duru=minutes per=1 peru=day
commit
6. DB Backup
/*--------------------------------------*//* Database Backup
*//*--------------------------------------*/
def script DBBACKUP "/* Run DB backups */"upd script DBBACKUP
"backup db devc=ts3310devc type=full wait=yes" line=005
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