MSA 2060 (iSCSI) Storage Space Question (Pool/Volumes)

[FoHE1]

Hi, 

I am new with MSA Storage and i have a question regarding the space available. 

We have a MSA2060 with the following Config: 

7 Disks (1 of it is a spare) each 1,92 TB 

Pool A:  7656.1 GB   (6 Disks Raid 6) 

Volume 1: 3479.9GB

Volume2: 3479.9GB

The Dashbaord shows us that we still have 2,6TB Available, but we are not able to expand the volumes by this amount, the max we can expand is ~ 600GB. Is this maybe connected to the Middle Threshold, which is set to 75% ?  Or why cant we expand the volumes by the full available space?

(We are not using any snapshots)

thank you in advance and sorry for the beginner question.

best regards

FoHe

[support_s]

System recommended content:

1. HPE MSA 2060 Storage Array - Overview

2. HPE MSA 2060 Storage Array - Specifications

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[FoHE1]

Thanks for these 2 documents, but i am not finding the answer to my question with the documents. 

[ArunKKR · Accepted solution]

Hi,

While creating a Pool by default over commit  is enabled.

From SMU guide:

https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=a00128580en_us

Overcommitting is a virtual storage feature that allows a system administrator to overcommit physical storage resources. This
allows the host system to operate as though it has more storage available than is actually allocated to it. When physical
resources fill up, the administrator can add physical storage by adding additional disk groups or expanding an MSA-DP+ disk
group.

Please check whether overcommit is enabled by executing the below command from putty SSH session.

show pools

From SMU - To check if the pool is overcommitted, go to Maintenance > Storage, then expand the pool row. If the Pool Overcommitted
value is True, the pool is overcommitted. If the value is False, the pool is not overcommitted.

With over commit disabled the maximum size of volumes (Total capacity of all volumes in the Pool) that you can create in the Pool will be around 7.6TB.
In your case only around 600GB free space is available as you have already created 2 volumes of size around 7TB.
If over commit is enabled you should be able to create new volumes of size more than 600GB.
You would get an informational alert related to over commit while trying to create volumes of size greater than 600GB.

The 2.6TB free space showing up in dashboard would be taking into consideration the allocated capacity (ie, used space of volumes at operating system end)
For example, if you have a 3.5TB volume presented to operating system and the OS partition uses only around 2.5TB in it, the dashboard will report free space as 1TB.

[JonPaul]

@FoHE1 
Can you send some of the Management Interface output?
I think with 6 drives in a RAID 6 of 1.92TB drives you would already be overcommitted.  Usable capacity (Thick Provisioned) should be < 4TB  (4 + 2 disk config)
I think you may be confusing Allocated vs Committed vs Free
The system will always Thin-Provision data,  only Allocate actual storage when it is needed. 

[FoHE1]

Hi @ArunKKR 

thanks for your explanation, it helped me a lot. 

the only thing i am not understanding for the moment is, that the msa shows a different size of the volumes thatn the ESX Servers, but i guess it is connected to the calculation of the size (1000/1024).

[ArunKKR]

Hi,

Operating systems usually show volume size in base-2. Disks usually show size in base-10.
MSA storage by default represents capacity in base 10 ie,TB , GB etc
In OS end it would be base 2 ie, TiB , GiB etc
You could use online TB to TIB or GB to GiB converters to check whether the space in OS end and MSA storage matches.

[JonPaul]

The MSA also offers an option to display in Base-2 rather than Base-10.  If that is selected then the MSA will match the capacity displayed at the OS. 
The setting is in both the CLI
CLI> set cli-parameters storage-size-base 2        # sets the current session to Base-2
CLI> set user storage-size-base 2  <username>   # sets the future <username> logs to use Base-B
In the SMU (WebUI):
- Goto the Settings Topic -> Users -> Click the 'edit' (Pencil Icon) and set the Base preference to Base 2
Looks like this setting takes immediate effect.