MD3000 - Delete Virtual Disk

Hello,

If you were to delete the raid group and recreate the VD & hot spare using the exact same disks selected then yes you can get your data back as you have not changed the config from when it was seen on the MD3000.  Now it is not guaranteed that you will get all the data back but most times you get it all back.  

B) restarting the server doesn’t make any difference except that the VD will not show up as it has been removed from the server when it was deleted.

C)  the Raid info is saved on the Controllers in the MD3000.  And until you put a new config on the controller the old config will still be present until the controller is updated by firmware or new VD assignment.

Let us know how it goes

Hi dell-SAM L,

thank you for your prompt response. so basically what I have understood from your post above :

a) If i log-on to MDSM

b) Create a Disk Group (of a different name) - would this be ok ?

c) Create a Virtual Disk (with a different name) - would this be ok ?

d) Then select exactly the same DISKS from the SAME enclosure as I had selected previously, select "RAID-6", select "Hot-spare"

e) It should bring my data back ?

How would I avoid virtual disk initializing ? I read some where we need to avoid that in-order to retain the data ?

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Would I then also need to map that Virtual Disk to both HBA's as they were mapped previously ? or would that come in automatically ?

will be grateful for your prompt response

will post my results and findings here

Sam

Hello,

A) yes

B) It should be in theory as you are creating the same setup just changing the name

C) It should be in theory as you are creating the same setup just changing the name

D) Yes that is correct

E) Yes as long as you don’t initialize any of the disk ( add to another virtual disk or raid group ) then yes there is a good chance that you can recover the data.

To avoid disk initialization as long as the disk are present but not part of any raid group or virtual disk.  Once a disk is made part of a raid group or a virtual disk then it has been initialized with that config.  

You should have to remap the Virtual disk to both HBA’s unless it automatically sees it on both.

Let us know how it goes

Hi Dell-Sam L,

Thank you for your prompt answers - it has been very helpful. Now :-) My findings of the practical are as follows :

So, I took out the secondary HBA (SAS5E) adapter and all of (2950+1xMD3000+1xMD1000) were running off it - Fine.

As I had previously removed all Disk groups and virtual disks (but had documented the configuration)

I re-created them exactly they were

I then changed Host Server in MDSM and mapped it to the HBA

Guess what : It bought up the disk as offline in Diskmgmt.msc on windows as 2 x 4TB Disks, so far so good (as that was the original layout)

MDSM showed background vdisk initializing

I then made two (2) disks in windows disk management ONLINE by right clicking and ONLINE

Now ... it brought the disks online but with 2 x 2TB partition each ? though my previous layout was 4TB x 2 Disks and no logical partitions under windows

I got disappointed :-(

Further to the disappointment , it offers to either create partition or format :-(

So - I guess no data ?

What do you suggest ?  I mean what do you think would have changed ?

Also, is there a way in MDSM or with these MD3000's that one create a virtual disk but without initializing with zeros, as when I checked the event logs in MDSM it showed initializing virtual disk with zeros - I guess thats where it all went south :-)

I am awaiting your expert insight - as I need to get this through !!

Much appreciated !
Sam

Hi SHANNONAGAN,

Thank you for your prompt and detailed reply. So do you think the situation I am in now - it's all gone or is there a chance ?

Dell support is out of question, due to the fact that these boxes are not in warranty and have been donated, I am only conducting these tests before they go into production - it's a long story but these tests will save us a lot of time in the future.

Now, where I stand is :

I have created the DiskGroups and VDs via MDSM, had I known of the cli - I would have gone that route.

I had created a RAID-6 virtual disk before and then again for testing out recovery.

a) I had created them with the defaults of offset and segment size and owner, via MDSM first time and second time as well, so when using the cli what would i write for those options like offset etc ?

b) as I have re-created the disk groups and vd's, do you think there is any point in deleting these vd's (no data or no format under windows has been done on them yet) and trying to re-create with the command you provide above ?

c) when you say re-create these commands, I can try myself if you could point me, or do you mean the smcli -n unamed commands are saved in a CSV file ? once created how would ONE execute these commands via the csv?

d) Do you think I should use R-Tools now on top of what I have already created or try another go by deleting and re-creating with cli ?

e) The command you mentioned - does that initialize virtualdisk with zeros or ?

Will look forward to your expert suggestions 

Thanks ever so much !!

Sam

If you have recreated in the MDSM tool, then the drives will be initialized, which will destroy the data.  The cli commands however give you the ability to create the VD w/o the initilization (thus the disaster recovery option or re-tag).

When you run the command to save the storage configuration to a text file, this file will in plain text contain all the options that the GUI auto configures for you.

Example of the output:

show "Creating RAID 5 Virtual Disk WitnessDisk on new Disk Group 0.";

//This command creates disk group <0> and the initial virtual disk with offset 0 on the disk group.

// NOTE: For Disk Groups that use all available capacity, the last Virtual Disk on this group is

// created using all remaining capacity by omitting the capacity= virtual disk creation parameter.

create virtualDisk physicalDisks=(0,0 0,1 0,2 0,3 0,4 0,5) raidLevel=5 userLabel="WitnessDisk" diskGroupUserLabel="0" owner=0 segmentSize=128 capacity=1073741824 Bytes dssPreAllocate=true securityType=none;

show "Setting additional attributes for Virtual Disk WitnessDisk.";

// Configuration settings that can not be set during Virtual Disk creation.

set virtualDisk["WitnessDisk"] cacheFlushModifier=10;

set virtualDisk["WitnessDisk"] cacheWithoutBatteryEnabled=false;

set virtualDisk["WitnessDisk"] mirrorEnabled=true;

set virtualDisk["WitnessDisk"] readCacheEnabled=true;

set virtualDisk["WitnessDisk"] writeCacheEnabled=true;

set virtualDisk["WitnessDisk"] mediaScanEnabled=true;

set virtualDisk["WitnessDisk"] consistencyCheckEnabled=true;

set virtualDisk["WitnessDisk"] readAheadMultiplier=1;

set virtualDisk["WitnessDisk"] modificationPriority=high;

set virtualDisk["WitnessDisk"] preReadRedundancyCheck=false;

show "Creating Virtual Disk-to-LUN Mapping for Virtual Disk WitnessDisk to LUN 0 under Host Group HV_Cluster.";

set virtualDisk ["WitnessDisk"] logicalUnitNumber=0 hostGroup="HV_Cluster";

The CSV file is a reference file for the size of the VD's that you created, use it to double check the values of the save file that you created.  This CSV is saved each time MDSM is opened so as you expand and change your array, then of course this config file will need to be adjusted to match.

The R-Tools would not be needed, as SMLI can and does doe it all.

And yes the initialize writes 0's on the blocks of the drives - which equal no good for DR but good for resolving other issues such as a punctured strip.

Hi shannonagan,

Thank you again for your detailed reply - very helpful and I am going to test and post here during the coming week.

So, what I have understood so far from your answer is, that basically we need the CSV file in order to verify the parameters and virtual disk / disk group configuration, when we are trying to re-create it with recovery from an accidental deletion or corruption. Right ?

Also, on the current situation - where I have re-created VDISK via MDSM, what would you suggest in order to get data back from the deleted vdisk ? Would any recovery tool help or shall i use SMCLI commands again to re-create vd and see if it brings something back?

Will be most grateful and will post in much detail about my findings later this evening or tomorrow.

Thanks again !
Sam