SCSI Reserve and Mount Point
- 10 years ago
Number 2, you can research yourself, give it a go, and report back what you find.
Number 1 I will help with, again you can also check the guides.
SCSI SPC-2 reserve is quite basic - a reservation is just put on the drive, for example by media server1. This prevents any other HBA from making a reservation on the drive (yes reservations 'come' from the HBA, so the drive is therefrore reserverd. The only way for the reservation to be released is for a scsi reservation release to be sent to the drive, from the same HBA, or by powercycling the drive.
This is fine, apart from if say you had a cluster and the machine using the drive fails. Another machine takes over but cannot release the drive, as this can only be done by the original HBA.
Persistent is more advanced, basically a reservation key is used, which using various utilities can be read from the drive itself - it looks like this:
dr-media1:/usr/openv/netbackup/logs/bptm # sg_persist --read-reservation -d /dev/sg5
IBM ULT3580-TD5 0103
Peripheral device type: tape
PR generation=0xb, Reservation follows:
Key=0x1d00006001e8488
scope: LU_SCOPE, type: Exclusive AccessThe main difference with this, is that if the key is read, it can be determined 'who' set the reservation. I'm not sure how, but I am told Engineering are able to determine if NBU 'made' the key. WHat this means is that if the original server, say media server1 set the reservation, a different media server can release it, providing NBU made the reservation.
- 10 years ago
Please read through the section in the manual that I have referred to above.
There is a section under this topic:
Recommended use for Enable SCSI reserve property
You will see that SCSI persistent reserve is especially important in your environment where your clustered master server nodes have tape drives attached.
You recently posted when there were issues with tape drives after master server failover.To know if your tape drives support SCSI persistent reserve, check the NBU HCL: http://www.symantec.com/docs/TECH76495