IDS Forum

RE: Onbar Pools and File System with ISM

Posted By: Stuart McCann
Date: Wednesday, 20 December 2006, at 8:14 p.m.

In Response To: Onbar Pools and File System with ISM (André Luiz Rufino)

1. What is really a disk pool and what is the device that I want to
write my
archive.

It can be a bit confusing Andre, but I'll have a go for you if you can
bear with me.

Onbar talks to an xbsa compliant storage manager; ISM is such a storage
manager with a limit of 4 connected devices at any one time.

Pools are organisational units managed by the storage manager. Onbar
backs up dbspaces, sbspaces, and blobspaces to physical media (volumes)
mounted on a device. These volumes would normally belong to the pool
defined in the $ONCONFIG file ISM_DATA_POOL parameter. Logical Logs are
backed up to volumes (media) in the pool defined in the ISM_LOG_POOL.

Out of the box, the ONCONFIG file designates ISMData and ISMLogs to
these parameters. The ISMData and ISMLogs pools are defined in the
bowels if ISM when you first run the ism_startup -init. It is essential
that
ism_startup -init be run (as root) on every host where you want to use
ISM. In addition, ISM creates the ISMDiskData and ISMDiskLogs Pools
during this initialization.

The ISMData and ISMLog pools are used to manage media mounted on Non
File Type Devices, eg: a tape drive like /dev/rmt0.

The ISMDiskData and ISMDiskLogs pools are used to manage File type
devices (directories).

I know I'm not talking disk pools yet, but hang in and I'll get there.

If you only had a single 4mm DAT tape drive to backup your database
server you would need to first add the tape device with:-

ism_add -device /dev/rmt0 -type 4mm

Before ISM can store data or logical logs on a tape the tape needs to be
registered as a volume with ISM. So, you would get the tapes you want to
use to store your backup on (you may need 2 or more depending on the
amount of Data), and label them one at a time using:-

ism_op -label -volume volumeName -pool ISMData and or ISMLogs.

This will write a header to each tape. This header is used to identify
what the volume name of the tape is when it is mounted on the tape
device for backup and restore operations. The volume is also registered
in the bowels of ISM along with the pool to which that volume belongs
and other info.

So now you come along and do an onbar -b -L 0 for the DBServer to be
backed up. In the ONCONFIG file the ISM_DATA_POOL and ISM_LOG_POOL would
be set to ISMData and ISMLogs respectively.

You can then use ism_watch to monitor activity and any messages that ism
needs to communicate to the backup operator, you presumably. For
example, if when you ran onbar there was not a labelled tape (volume)
mounted in the tape drive; ism_watch would prompt you to mount a tape
registered with ISM in the ISMData pool. Onbar will wait for ISM to tell
it that it is ready to start storing the backup data/logs.

So, the idea is that you pre-register volumes in pools before you use
them. This registration can be while the backup is going on, but usually
you would prepare your media to fit in with you backup schedule.

Now, if you want your backups to be stored on a file system(s) ISM needs
to use a different driver, a file driver if you like as opposed to a
tape (non file) driver. However the concept of media management is the
same as with tapes. You need to create a directory which will serve as
both the device and the volume.

So you need to make 1 or more directories and add them as devices (up to
4 at a time) with:

Ism_add -device /pathToDirectory -type file
To turn the directory into a volume, you need to label it with:-

Ism_op -label volumeName -pool ISMDiskData or ISMDiskLogs

This creates a couple of files (.nsr and volume) in the directory which,
like with the tape media, identify the volume. The volume and its pool
are
Now that the directory (device) is labelled (a registered volume), you
can mount it with:-

Ism_op -mount /pathToDirectory

Note that the volume name is not does not have to be the same as the
directory(basename of device), but it might suit you to have it that
way.

Must go. Hope that make sense and is of some help to you.

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Messages In This Thread

• Onbar Pools and File System with ISM
  André Luiz Rufino -- Wednesday, 20 December 2006, at 1:02 p.m.
  • Re: Onbar Pools and File System with ISM
    Roger Kee -- Wednesday, 20 December 2006, at 1:43 p.m.
  • RE: Onbar Pools and File System with ISM
    Stuart McCann -- Wednesday, 20 December 2006, at 8:14 p.m.

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