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July 20th, 2015 01:00

relation between disks and Luns

Hi, I know that LUNs are parts of some disks which will be presented to a host. For example in a RAID 5 (4+1) a LUNs will be sectors from the five disks I hope this is right. But there is something I can't understand which is how many LUNs shall we create and how can I see the relations between LUNs and Disks. For example in this SPcollect output are the LUNs (50-->59) the ones that belongs to disks (1.1.4-->1.1.0) or those (4039-4030) ? What does FLU and ALU stand for ? and is there a way to see the LUNs that belongs to a RG through unisphere ?

MLU TPID ALU   FLU RGRP  ENCTYPE   TYPE   PRIV  LD   CAPACITY CACHE DEFOWN   STATE           NAVIFRUS

-         2    4039   50    120      SAS          RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -       2    4038   51    120      SAS          RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -       2    4037   52    120      SAS          RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -       2    4036   53    120     SAS           RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -      2    4035    54    120     SAS           RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -      2    4034    55   120      SAS           RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -      2    4033    56    120     SAS           RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -      2    4032    57    120     SAS           RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -      2    4031    58   120     SAS            RAID-5   Y     PLU   214.7 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

  -      2    4030    59    120    SAS            RAID-5   Y     PLU   213.8 GB   RW-     SP-A           ENA      1.1.4 1.1.3 1.1.2 1.1.1 1.1.0

4 Posts

July 20th, 2015 20:00

https://www.emc.com/collateral/hardware/white-papers/h1024-clariion-metaluns-cncpt-wp-ldv.pdf

43 Posts

July 20th, 2015 04:00

LUN details.png
and is there a way to see the LUNs that belongs to a RG through Unisphere? : Login to Unisphere, then Go to Storage --> Storage Pools --> select Raid Groups tab --> Select the Particular Raid group. Then you will be able to see the LUN belongs to that particular raid group just below

22 Posts

July 20th, 2015 06:00

Thanks, but the RAID Group is a Private one. We created a Pool and not a raid group. We have a Pool 0 that contains a lot of disks and a lot of Private RAID Group. Five disks that belongs to this pool forms a Private RAID Group and they are showing issues with the data. I want to know to which LUNs they belongs so I can know the data they contain.
Thank you ree and I hope you still can help

22 Posts

July 20th, 2015 07:00

Thanks,
It's a VNX5300 Block, The messages is "820 Soft media errors Bad Block".
Is it possible to figure out the LUN related to the hole Private RAID Group and not to a single disk ?

2 Intern

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715 Posts

July 20th, 2015 07:00

When you create a Pool, private RAID Groups are created according to the drive counts you select (4+1 etc).

When you create a LUN and consume the space, it is created in 256MB (for VNX2/ 1GB for VNX1) slices that are distributed across the Private RAID Group(s), and thus the underlying disks. I don't think you can really relate a slice of data to a particular disk in the underlying private RAID Groups.

ALU is the Array Logical Unit, which is used for addressing Array side, and not exposed to any hosts and is fixed.  Unlike a HLU which is definable and exposed to the host for addressing. FLU is the Flare LUN or RAID group LUN.

What issues are you having with the data and what model VNX is this ?

2 Intern

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715 Posts

July 20th, 2015 07:00

naviseccli -h arraysp -getlun lunid      ........and try the -sftscsi and -private options

You could isolate which disk(s) are causing the errors through unisphere also, and if the counts are high replace them accordingly,

22 Posts

July 20th, 2015 07:00

Thanks Brett. One last request. Could you suggest me a good document that explains the concepts of LUNs, ALU, FLU.

22 Posts

July 20th, 2015 23:00

Thanks Yogesh, it's much more clear for me.

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