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Database device on NFS disk
11-24-2011, 08:10 AM
Post: #1
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Database device on NFS disk


Hi Gurudev,

I have a query related to Sybase and NFS device.

Suppose there are two Server HostA and HostB.

HostA
- OS SUSE Linux
- Sybase ASE is installed
- NFS Client is installed
- User database device folder is /dbdata/data_local and /dbdata/data_remote

HostB
- OS SUSE Linux
- NFS Server is installed
- NFS shared folder is /dbdata/data

1) Create Sybase user on both the server with same user id and group id
2) NTP Server should be configured to sync both server.
3)NFS Server is setup on HostB
4) NFS Client is setup on HostA
5) Mounted HostB folder /dbdata/data on HostA folder /dbdata/data_remote
6) Ownership of /dbdata/data of HostB and /dbdata/data_local is given same and chmod changed to 777
7) Now user database which consist of total 7 devices
- device1 for non partition tables
- device2 for log device
- device3 to device7 used for Partitioning tables


Qn.
Can I place few device on HostA and few device on HostB?
Is Sybase15.5 ASE supports this feature?

Thanks and regards,
Ranjit


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11-25-2011, 07:13 AM
Post: #2
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RE: Database device on NFS disk


This is what I think

They are not two seperate filesystem to place few devices/files on HostB and few on HostA.
If the filesystem is on HostB and is NFS shared to HostA, even if you create files/devices from HostA effectively they would get created on the filesystem on HostB.

It does not make any difference where(HostA or HostB) you create the files/devices from as ultimately they get created on the FS on HostB.

You may try testing this.


Nag


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11-28-2011, 03:21 AM
Post: #3
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RE: Database device on NFS disk


    (11-24-2011 08:10 AM)ranjitsybaseteam Wrote:  I have a query related to Sybase and NFS device.

    (snip)

    Can I place few device on HostA and few device on HostB?

Sybase ASE is a stand-alone server. Why would you want some devices on the host (which Sybase is deployed on) and some devices on another host ???

Using NFS is fine for emergencies (eg. testing a Disaster Recovery scenario) or bcp operations, etc. but not for Sybase Devices. NFS and NAS runs across the network, so it is very slow. Sybase is supposed to have its Devices on local disk or SAN only (Raw Partitions, but if you have a baby o/s, then file system files).

So they answer is, yes you can, but it is not reasonable or technically logical, to actually want slow devices, and to deploy ASE across the network. Fine for emergencies and very temporary needs, but not otherwise.
    Quote:Is Sybase15.5 ASE supports this feature?
What "feature" exactly, do you mean ? I have never heard of anyone who wants their Sybase ASE to run slower (NFS), or wants that as a "feature".

1. All Sybase versions "support" NFS devices. All Sybase sees is the file system node. How the file system is deployed, is outside Sybase: it does not know if the file is SAN/NFS/NAS/Local Disk.

In this scenario, Host B is not a "Host"; it is just the location where "some" of your files are located, accessible via NFS from Host A, and Host A is all that counts. And if Host B goes down, the entire database on Host A will be unavailable and has to be recovered from dump files.

2. If you are talking about exporting an entire database to another Sybase ASE server, by moving its devices, as distinct from the DUMP/LOAD DATABASE method, then yes, we have had that since 12.5.4. That is one of the very temporary uses. Read up on the MOUNT and QUIESCE DATABASE commands.



Ashirvad to my Shishyas, Cheers to the others
Derek Asirvadem
Information Architect / Sr Sybase DBA
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Selection of Useful Documents for the Sybase DBA
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