What is SCSI Persistance Reserve in Netbackup
What is SCSI Persistance Reserve in Netbackup and what is the advantage of this in Netbackup environment.Please guide me
Have you had a look at the Admin Guides yet?
Extract from Administrator's Guide for Windows I http://www.symantec.com/docs/TECH127079 :
p. 156:
The SCSIpersistentreserve option provides SCSI persistent reserve protection
for SCSI devices. The devices must conform to the SCSI Primary Commands -
3 (SPC-3) standard. SCSI persistent reserve is valid for NetBackup 6.5 and later
servers only. If you enable SCSI persistent reserve, NetBackup does not send
persistent reserve commands to NetBackup media servers earlier than release
6.5.Note: Ensure that all of your hardware processes SCSI persistent reserve commands
correctly. All of your hardware includes Fibre Channel bridges. If the hardware
does not process SCSI persistent reserve commands correctly and NetBackup is
configured to use SCSI persistent reserve, no protection may exist.p. 159:
Recommended use for Enable SCSI reserve propertyAll tape drive and bridge vendors support the SPC-2 SCSI reserve and release
method. NetBackup has used SPC-2 SCSI reserve since NetBackup 3.4.3, and it is
the default tape drive reservation method in NetBackup. SPC-2 SCSI reserve is
effective for most NetBackup environments.
The SCSI persistent reserve method may be more effective in the following
environments because it provides device status detection and correction:
■ NetBackup media servers operate in a cluster environment.
NetBackup can recover and use a reserved drive after a failover (if NetBackup
owns the reservation). (With SPC-2 SCSI reserve, the drive must usually be
reset because the reservation owner is inoperative.)
■ The drive must have high availability.
NetBackup can resolve NetBackup drive reservation conflicts and maintain
high drive availability. (SPC-2 SCSI reserve provides no method for drive status
detection.)
However, the SCSI persistent reserve method is not supported or not supported
correctly by all device vendors. Therefore, thoroughly analyze the environment
to ensure that all of the hardware supports SCSI persistent reserve correctly.
Symantec recommends careful consideration of all of the following factors before
Enable SCSI reserve is used:
■ Only a limited number of tape drive vendors support SCSI persistent reserve.
■ SCSI persistent reserve is not supported or not supported correctly by all fibre
channel bridge vendors. Incorrect support in a bridge means no access
protection. Therefore, if the environment uses bridges, do not use SCSI
persistent reserve.
■ If parallel SCSI buses are used, carefully consider the use of SCSI persistent
reserve. Usually, parallel drives are not shared, so SCSI persistent reserve
protection is not required. Also, parallel drives are usually on a bridge, and
bridges do not support SCSI persistent reserve correctly. Therefore, if the
environment uses parallel SCSI buses, do not use SCSI persistent reserve.
■ The operating system tape drivers may require extensive configuration to use
SCSI persistent reserve. For example, if the tape drives do not support SPC-3
Compatible Reservation Handling (CRH), ensure that the operating system
does not issue SPC-2 reserve and release commands.
If any of the hardware does not support SCSI persistent reserve, Symantec
recommends that SCSI persistent reserve is not used.