File System lock on VxFS

[Habeeb]

Hi,

I have two servers where a disk on SAN is mapped to both the servers. On one server, this disk is used to create VxFS file system and it is imported & actively used by the machine. Apparently, by mistake administrator used the same disk from the other server and formatted from it. Is this avoidable? does Veritas has any feature to lock the file system ( i know about IO fencing that can be used in local clusters) so that mistake by SAN administrator by making disk visible to both machines and mistake of system administrator using disks used by other machines can be avoided?

Please let me know if you are unable to understand the scenario,

Regards

Habeeb

[Antony_Pavlenko]

Hello.

First of all, if you use vxvm under vxfs you lready have somekind of protectionfromusererrors.You couldn't import diskgroup (with file system) on two server's ( with out of force flag of cause ). If you have no vxvm that at vxfs level there is no such kind of protection.i

[Mayank_Vasa]

Hello Fitwell:

What version of VCS, VxFS, VxVM are you using? And which commands did the admin use to format the disk - were these native tools, VxVM or VxFS commands?

I/O fencing can be used to protect against native tools. Disk access will be rejected from other hosts in the cluster that don't have the DG imported.

For VxFS commands, a new feature was added to the Mount agent in VCS 5.0MP3 called VxFSMountLock. Description from Bundled Agents Guide:

"This attribute is only applicable to Veritas (VxFS) file systems. This attribute controls a file system locking feature to prevent accidental unmounts." More details can be found in the Bundled Agents Guide for VCS 5.0MP3 at http://sfdoccentral.symantec.com/sf/5.0MP3/solaris/pdf/vcs_bundled_agents.pdf page 44.

Hope this helps,

+ Mayank.

[Habeeb]

Many thanks for the replies: let me explain the specific case we had,

There was a disk (on SAN) that was presented to two servers, viz one Linux server with VCS, VxFS & VxVM and to a AIX server which is running with native OS (AIX 5.3). Linux is running some production application and it had data on this particular disk. By mistake AIX administrator added this particular disk to his native volume group with LVM, that deleted entire data that was there on the disk. As you might be aware once AIX-LVM takes control of a disk, you can't take the disk back until it is manually released from AIX. Does Veritas has similar features where it locks the disk so that other servers outside the cluster can't take the disk to control? will the feature "VxFSMountLock" in vcs5.0MP3 help me out to achieve this?

Regards
Habeeb

[TomerG]

There is no way to prevent this type of stuff-up without hardware reservations which would prevent one host from physically writing to the disk (which is what I/O Fencing would enable, for example).

VxFSMountLock, etc would not prevent this behavior.