System information

Adjust Queue Depth for an Emulex HBA
If you are not satisfied with the performance of your Emulex adapter, you can change its maximum queue
depth.
Procedure
1 Verify which Emulex HBA module is currently loaded by entering the vmkload_mod -l | grep lpfcdd
command.
2 Run the following command.
The example shows the lpfcdd_7xx module. Use the appropriate module based on the outcome of
Step 1.
vicfg-module -s lpfc0_lun_queue_depth=16 lpfcdd_7xx
In this case, the HBA represented by lpfc0 will have its LUN queue depth set to 16.
3 Reboot the host.
SAN Storage Backup Considerations
In the SAN environment, backups have two goals. The first goal is to archive online data to offline media. This
process is repeated periodically for all online data on a time schedule. The second goal is to provide access to
offline data for recovery from a problem. For example, database recovery often requires retrieval of archived
log files that are not currently online.
Scheduling a backup depends on a number of factors:
n
Identification of critical applications that require more frequent backup cycles within a given period of
time.
n
Recovery point and recovery time goals. Consider how precise your recovery point needs to be, and how
long you are willing to wait for it.
n
The rate of change (RoC) associated with the data. For example, if you are using synchronous/
asynchronous replication, the RoC affects the amount of bandwidth required between the primary and
secondary storage devices.
n
Overall impact on SAN environment, storage performance (while backing up), and other applications.
n
Identification of peak traffic periods on the SAN (backups scheduled during those peak periods can slow
the applications and the backup process).
n
Time to schedule all backups within the datacenter.
n
Time it takes to back up an individual application.
n
Resource availability for archiving data; usually offline media access (tape).
Include a recovery-time objective for each application when you design your backup strategy. That is, consider
the time and resources necessary to reprovision the data. For example, if a scheduled backup stores so much
data that recovery requires a considerable amount of time, examine the scheduled backup. Perform the backup
more frequently, so that less data is backed up at a time and the recovery time decreases.
If a particular application requires recovery within a certain time frame, the backup process needs to provide
a time schedule and specific data processing to meet this requirement. Fast recovery can require the use of
recovery volumes that reside on online storage to minimize or eliminate the need to access slow offline media
for missing data components.
Chapter 6 Managing ESX/ESXi Systems That Use SAN Storage
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