Detecting whether a LUN is being used

Question

Hello Everyone,

We have a Clariion CX500 and I've run into a peculiar issue. I inherited the management of this SAN and as a result, I've had to do some fumbling to find out what my predecessor did on this SAN.

At the current moment, we have 100GB FC LUN in which I have no idea whether it is being used or not. When I look at the Storage Group in Navisphere, the host name, IP and agent are not reachable. I know for a fact that the host name and IP are for a server that was removed from our system about 3 years ago.

How can I tell if this LUN is being used by another host? When I look at the disk statistics within the LUN, it looks like there is activity. But I can't tell if that means the disks are being written to or if the I/O is just general usage by the SAN.

Thanks in advance for your advice/help.

Sean

dynamox · Accepted Answer

Sean, if you expand SPA and SPB you should see all LUNs on that array, if LUN is assigned to multiple hosts, it will list their name next to the LUN name.

seanka1 · Answer

You were right!  Looks like there aren't any other hosts using that LUN.  Yay, 100 GB of more space for me to play with. Thanks again for your help. Sean

kelleg · Answer

You might also want to review the latest Best Practices guides for CLARiiON - while the guides may be for a later flare revision than the one on your CX500, the information about configuring LUNs and Raid groups contains good information about configuring for best performance:

EMC CLARiiON Storage System Fundamentals for Performance and Availability

http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/H1049_emc_clariion_fibre_channel_storage_fundamentals_ldv.pdf

EMC CLARiiON Best Practices for Fibre Channel Storage: FLARE Release 26 Firmware Update - Best Practices Planning

http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/H2358_clariion_best_prac_fibre_chnl_wp_ldv.pdf

White Paper: An Introduction to EMC CLARiiON Storage Device Technology — Applied Technology

http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/H4208-an-intro-emc-clariion-hard0drive-tech-wp.pdf

White Paper: The Influence of Priorities on CLARiiON LUN Management Operations - Applied Technology

http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/H4153-the-influence-of-priorities-on-lun-mgmt-optns-wp.pdf

RRR · Answer

A less acurate way of telling is to view the properties of the LUN and have a look at the stats page. There should be no I/O's whatsoever. But having sayd that, there could be a server owning this LUN which is not actually doing anything with it.

sar2k76 · Answer

Use Reports and generate Storage Group Report and check if any HOST is assigned any lun or metalun for confirmation.

Then drill down the LUN folder in the navisphere manager for that storage group and check and confirm its use?

Hope this will give you some clarifications.

CLARiiON

Detecting whether a LUN is being used

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