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samstorage
1 Copper

MD3000 - Delete Virtual Disk

Hello all,

So, I am just learning about all these disk groups, virtual disks etc. I have a Dell MD3000, MD1000 connected with a Dell PE Server. All Good, I have setup MDSM on my laptop and on the server itself, all connected to the LAN.

I have all drive bays populated on both enclosures.

As a test and I got this thought from the following link and text :

http://support.dell.com/support/edocs/software/svradmin/1.9/en/stormgmt/vdtkdel.html

If you delete a virtual disk and immediately create a new virtual disk with all the same characteristics as the one that was deleted, the controller will recognize the data as if the first virtual disk were never deleted. In this situation, if you don't want the old data after recreating a new virtual disk, reinitialize the virtual disk.

Question is :


I created a Disk Group called DiskGroup1 and created a VirtualDisk utilizing all drives on ONE (1) enclosure with 1 HOT SPARE in a RAID-6 configuration, so my config looks like :

MD3000 : RaidGroup1 > VirtualDisk1

I copied some data to it - around 1TB file and folders data.
I have now deleted the virtual disk and the raid group from within the MDSM on this MD3000.

a) If I re-create the RaidGroup with the same name and then re-create the VirtualDisk with the same name and physical disk members and assign one hot-spare as i previously did, will I get my data back ?

b) If I had restarted the server, would that matter in the above case ?

c) Where does the MD3000 saves RAID information / Vdisk information ?

d) If none of the above is possible, which tool would ONE recommend to recover data in such a scenario ?

e) I have R-Studio (R-tools) (http://www.r-tt.com/) Version 5.2, to use this tool, shall I re-create the RaidGroup and VDISk and run the tool or ?

will be grateful for your insight as i would be the only person managing this storage box - so I have to learn it, it is for a charity org - so not much funds - this box is donated from a vendor to our charity - Thanks so much !

thanks for reading - excuse me if I had asked a not very sensible question, I just want to be prepared  ๐Ÿ™‚


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8 Replies
Moderator
Moderator

Re: 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 doesnโ€™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

DELL-Sam L
Dell | Social Outreach Services - Enterprise
Download the Dell Quick Resource Locator app today to access PowerEdge support content on your mobile device! (iOS, Android, Windows)

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samstorage
1 Copper

Re: MD3000 - Delete Virtual Disk

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 ?

---

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

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Moderator
Moderator

Re: MD3000 - Delete Virtual Disk

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 donโ€™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 HBAโ€™s unless it automatically sees it on both.

Let us know how it goes

DELL-Sam L
Dell | Social Outreach Services - Enterprise
Download the Dell Quick Resource Locator app today to access PowerEdge support content on your mobile device! (iOS, Android, Windows)

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samstorage
1 Copper

Re: MD3000 - Delete Virtual Disk

Hi Dell-Sam L,

Thank you for your prompt answers - it has been very helpful. Now ๐Ÿ™‚ 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 ๐Ÿ˜ž

Further to the disappointment , it offers to either create partition or format ๐Ÿ˜ž

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 ๐Ÿ™‚

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

Much appreciated !
Sam

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shannonagan
1 Copper

Re: MD3000 - Delete Virtual Disk

a) If I re-create the RaidGroup with the same name and then re-create the VirtualDisk with the same name and physical disk members and assign one hot-spare as i previously did, will I get my data back ?

- so yes and no.  No if you use the MDSM tool to create the new DiskGroup and VirtualDisks.  Yes if you use the SMCLI commands similar to:

smcli -n "unnamed" -c "recover virtualDisk physicalDisks=(0,0 0,1 0,2 0,3) newVolumeGroup=\"DiskGroup1\" userLabel=\"VirtualDisk1\" capacity=1798765019136 offset=0 raidLevel=5 segmentSize=128 owner=0;"

b) If I had restarted the server, would that matter in the above case ?

c) Where does the MD3000 saves RAID information / Vdisk information ?

- the reboot of the server in this instance would not really make a big difference.  The array is what creates and holds the diskgroup and holds it on the controllers and harddrives in a small database that is hidden across all drives.

d) If none of the above is possible, which tool would ONE recommend to recover data in such a scenario ?

-if you needed to recover the data in this situation, you would have to use a CSV file inside the Dell\MDSMxx\client\recovery folder to create the commands above.  Typically if you run into this situation, I suggest contacting Dell support.  They have been able to take either that recovery file or a prior support bundle from the array and recreate these commands as a courtesy.  So it might be a good option to make a support bundle once a month or so as a "ace" in the hole option / or another option (imo the best) would be to save the configuration file with

client>smcli 123.45.67.89 -c "save storageArray configuration file=\"c:\folder\storageArrayconfig1.scr\";"

CLI Guide for the array:

support.dell.com/.../CLIMR2g.pdf

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samstorage
1 Copper

Re: MD3000 - Delete Virtual Disk

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

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shannonagan
1 Copper

Re: MD3000 - Delete Virtual Disk

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 <WitnessDisk> 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.

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samstorage
1 Copper

Re: MD3000 - Delete Virtual Disk

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

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