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MSA2040 - Expanded size by 2 TB but Allocated size stays still.

 
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mesutk
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MSA2040 - Expanded size by 2 TB but Allocated size stays still.

Hello, I have 2040 (currently 13  x 1.2TB 10K SAS disks) -Raid 6-

 

Pool details: Total size: 13.1 TB, Class: Virtual, Avail: 3930.6 GB, Volumes:1 Disk Groups: 1

Volumes: Class:Virtual, Size:13.1 TB, Allocated: 9.3 TB

 

This volume was 10 TB before, I deleted other 2 volumes and added the space of these volumes to main one. The thing is, size is expanded to 13.1 TB, but its allocated size is not changed.

Is it because I have 13 disks installed with Raid 6 configuration? I bought anothe 11 disks (1.2 TB 10k SAS), but I want to make sure if its because of odd number of disk.

What could I do to use all available space?

Also df -h results (the server where I use this volume);

/dev/sdb                 9.4T  8.3T  1.1T  89% /msa10tb

 

Edit: Attached screenshots of Pool, Volume, Capacity and Storage.

7 REPLIES 7

Re: MSA2040 - Expanded size by 2 TB but Allocated size stays still.

In general whatever space you see as Allocated in MSA that means data written in that space in Pool level or VDG level but the space shows as Unallocated means volume not yet written data in it. So unallocated space related to volume level

If I take your example, in case of Pool A total size = 13.1TB

Provisioned size of volume named v04_10TB = 13.1TB

Allocated size of v04_10TB = 9.3TB

This means unallocated size at the volume level = (13.1-9.3)TB = 3.8TB  [This space not dedicated for any particular volume, this can be use by any volume part of that Pool]

I understand you have expanded volume size but the host side your host operating system support online volume expansion at the file system level? if not then I would suggest you to unmap the volume and remap the volume to host to get the expanded provisioned size of the volume

 

Hope this helps!
Regards
Subhajit

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mesutk
Frequent Visitor

Re: MSA2040 - Expanded size by 2 TB but Allocated size stays still.

Thanks for prompt response Subhajit,

The thing is I set up a new host after increasing the size of the volume and mapped it. So, basically I did what you said by mapping the host with new values.

Operating system is : CentOS Linux release 7.5.1804 (Core). Do you recommend to use 3rd party tools like GParted to make sure if its a host-based issue?

Kind regards,

Mesut.

Re: MSA2040 - Expanded size by 2 TB but Allocated size stays still.

This is purely OS specific.

I am not an OS expert but what I can recollect is we should do vgmodify followed by lvextend followed by extendfs. I am not sure equivalent command in CentOS

 

 

Hope this helps!
Regards
Subhajit

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mesutk
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Re: MSA2040 - Expanded size by 2 TB but Allocated size stays still.

Hello Subhajit,

First of all thank you very much for the information you provided and suggestion you made. As you said the problem was OS specific and I fixed it by only typing;

'xfs_grow /MOUNT_PATH'

I have a side question, according to my setup (vdisk, r6); I will install 5 more 1.2 TB 10K SAS disks, what method should I follow? Could it be done online or do I have to take whole system offline? and How can I add these disks to my pool?

Thanks again!

Re: MSA2040 - Expanded size by 2 TB but Allocated size stays still.

I am not sure about the entire setup or configuration of this MSA. However, let me try to help you with the following information.

If you have only one Pool present in the system and you want to add 5 new 1.2TB SAS drives to the existing pool then it's not recommended with current number of drives. The recommended method to increase the volume size is to add a new Virtual Disk Group with the same amount of drives and RAID type as the existing Virtual Disk Group has. MSA uses wide striping which means data will be span accross all VDG in that Pool. I hope you remember that we can't expand existing VDG so we have to create new VDG with new drives and add them into Pool. Now due to mismatch of number of drives in particular VDG you will face performance issue as well as one VDG may run out of space than other VDG which is never recommended.

So solution would be either you buy another 8 new 1.2TB SAS drives and create new VDG with 13 drives with RAID6 like your existing VDG and add it to the same Pool where your existing VDG part of it.

Otherwise create a new VDG with these 5 new 1.2TB SAS drives and add it to other Pool from which new volumes can be created or if any existing volume already here then they can use this expanded space of the Pool as well but keep that in mind existing volumes  created from 1st Pool existing VDG space can't use this space. In Virtual storage a Volume is tied to a Pool.  This means that a Volume cannot span accross Pools.

 

Hope this helps!
Regards
Subhajit

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mesutk
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Re: MSA2040 - Expanded size by 2 TB but Allocated size stays still.

Yet another great explanation, thank you!

I will purchase 7 more disks since I can install only 11 more disks (13 installed). My configuration is like;

I have 1 pool that has 1 volume and 1 disk group. And the disk group I have is RAID6, Virtual and has 13 disks installed. So as far as I understand it is not possible to add new disks to my existing disk group instead create a new one. So to equalize the number of disks, am I allowed to reduce the number of existing VDG by 1 to make them 12-12? Also to make sure; I'll be able to use all these space for 1 volume without losing any data right? :)

I am sorry I am software expert and I 'must' deal with storage configuration too, so I don't have much knowledge about robust configuration :)

I am also attaching the whole setup I have under attachments.

Thanks again for enlightening me!

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Solution

Re: MSA2040 - Expanded size by 2 TB but Allocated size stays still.

There is no option to increase or reduce drives from existing VDG. It's better to take data backup and then delete the existing VDG. Then buy 11 drives and create new VDGs as per your requirement. 

 

 

Hope this helps!
Regards
Subhajit

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