HPE EVA Storage

san : file write on physical device

 

san : file write on physical device

hi,

we have san storage with dm multipath. Now we want to know when we write any file, on which physical device it is getting written? from filesystem end, we are not able to know as to on which msa (physical device) it is getting written.
2 REPLIES 2
klb
Valued Contributor

Re: san : file write on physical device


In the case of HP's EVA SAN, don't think you can do that without some really specific tracing and trace log analysis. Those traces and subsequent log file writes can pose a really heavy performance penalty.

Hth,

-klb
Johan Guldmyr
Honored Contributor

Re: san : file write on physical device

Hi!

Below I assume you want to find on which disk inside the MSA the data is stored on.
But after writing, I wondered maybe you want to be able to see in the OS which LUN you have presented to that server? If so, which MSA do you have? It should be possible to identify it from the MSA interface, I suspect it might be hard to find from within the server OS.

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On the EVA I would propose that it's relatively impossible to find out exactly on which disk a specific block/file are stored.

You say MSA (physical device) - but there are quite a few versions of MSA around. Which one do you have? Any also quite relevant: what RAID are you running on the SAN?

Also, why do you want to know this?

To aid recovery purposes?

I think this might be hard to find out.. if you run RAID5 you would need all the disks in the raid set to be able to recover the data anyway. Or at least all minus one - at least.

Maybe there are 3rd party tools(in the restore business) that would be able to help you identify on which physical device a file is.