HPE EVA Storage

Presenting LUN to 2nd server as read only?

 
Chris_Dove
Occasional Advisor

Presenting LUN to 2nd server as read only?

We're investigating DP6.0 D2D2T to increase our backup speeds, but as a quick solution what would be the implications of also publishing the LUNs to the server which hosts DP6 as read only, and backing them up from there?
5 REPLIES 5
Uwe Zessin
Honored Contributor

Re: Presenting LUN to 2nd server as read only?

Don't do that.

1.: some file systems cannot be mounted read-only

2.: the read-only view is not 'stable' (as the R/W sever is making constant changes) which can result in pretty bad file system inconsistencies.

See if your storage array can provide crash-consistent snapshots at least (required if database span multiple disks).
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Chris_Dove
Occasional Advisor

Re: Presenting LUN to 2nd server as read only?

Thanks for the reply,

We have an EVA4000 with business copy, but are only licensed for 1tb at the moment. This is only an interim solution so will look into alternatives rather than the Read only
Patrick Terlisten
Honored Contributor

Re: Presenting LUN to 2nd server as read only?

Hello,

don't do that... This "feature" is only used in some rare situations (cluster extension for example). It will not solve you problems. NTFS can't be cleanly mounted read-only. Windows will try to write some data to the MFT and will report errors, that filesystem can't be written.

Best regards,
Patrick
Best regards,
Patrick
SAN_8
Frequent Advisor

Re: Presenting LUN to 2nd server as read only?

It is only reccomended for EVA Clx
Uwe Zessin
Honored Contributor

Re: Presenting LUN to 2nd server as read only?

'only recommended' ? CLX _requires_ it.

Last time I checked, an EVA cannot present a single virtual disk to one host R/W and to another host R/O, because the RW/RO switch is a characteristic of the whole virtual disk. And even if it were possible, you still have the consistency problem I mentioned.


Don't know why you bring up CLX, access to the destination disk is usually blocked - see the "-forceflag" documentation.
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