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Re: MSA 2050 Change Pool Settings - Overcommit Flag cannot be disabled

 
RobI_1
Advisor

Re: MSA 2050 Change Pool Settings - Overcommit Flag cannot be disabled

home.jpg

Re: MSA 2050 Change Pool Settings - Overcommit Flag cannot be disabled

Thank you for sharing the Home Screen details.

According to that, you can see that total Virtual Disk Group size 8401 GB, out of that Allocated 4725 GB and unallocated 2462 GB. Which means reserved space left = [8401 - (4725 + 2462)] = 1214 GB

Now there are two Pools and Two disk-groups which means for each disk-group 607 GB got reserved. Your Thin provisioned Volume Size was 3594 GB .and Disk-group Size also 3594 GB. This the main reason when you try to disable overcommit option that time it's greyed out which means with current condition not possible.

 

Hope this helps!
Regards
Subhajit

I am an HPE employee

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RobI_1
Advisor

Re: MSA 2050 Change Pool Settings - Overcommit Flag cannot be disabled

Hi, apologies but is very hard to follow these calculations criteria.

I have 1 Disk Group in RAID 5 assigned to POOL A made of 8*600GB disks, totals up to ~4.2TB Netto.

From This POOL A we publish a Volume of 3593.9 GB as LUN 1 to VMware and we use ~70% of that.

Disk Group 1 shows 1542.5GB free.

Can you tell me why, it is not possible to thick provision this Volume?

It is hard to follow the new way HP has obliged us to use for the virtual arrays, the fact the linear capability was removed is very annoying and even more annoying is that we cannot add single disks to expand capacity.

 

 

 

Re: MSA 2050 Change Pool Settings - Overcommit Flag cannot be disabled

Yes there is difference between linear array and Virtual array.

In case of linear array all volumes Thick volume only but in Virtual array all volumes by default Thin Volume only.

In todays world most people interested in Thin Volume only because space should be allocated based on demand from backend rather than allocating entire space in 1st day itself which is the case of Thick volume. Lots of wastage of space.

Virtualization is a technology which helps to save price like pay as you use concept.

HPE came up with Virtualization technology with entry level Storage like MSA which is really great.

Applogise for the earlier Calculation which was not correct and I have corrected it.

Now coming to your setup, you are considering 7 x 600Gb drives which is approx 4.2TB physical space but when you create RAID 5 disk-group that time some space gets reserved as RAID parity and metadata for which affective space you get (4200-606) = 3594GB

Out of this VDG space already 2052 Gb got allocated and 1541 Gb unallocated space.

Virtual volumes make use of a method of storing user data in virtualized pages. These pages may be spread throughout
the underlying physical storage in a random fashion and allocated on demand. Virtualized storage therefore has a
dynamic mapping between logical and physical blocks.

Linear volumes make use of a method of storing user data in sequential fully allocated physical blocks. These blocks have
a fixed (static) mapping between the logical data presented to hosts and the physical location where it is stored.

This is the main reason when you try to disable overcommit option that time it look for sequential blocks or pages to allocate but it will not get that and that is the reason overcommit disable not possible in your case. 

So the solution is if you want to convert Thin Volume to Thick Volume then you need same size of space where sequeatial physical blocks available means 3594GB of sequential blocks required.

 

Hope this helps!
Regards
Subhajit

I am an HPE employee

If you feel this was helpful please click the KUDOS! thumb below!

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RobI_1
Advisor

Re: MSA 2050 Change Pool Settings - Overcommit Flag cannot be disabled

Does this mean we have to add 8*600GB disks to each pool in order to switch them to thick? Or less?

 

Re: MSA 2050 Change Pool Settings - Overcommit Flag cannot be disabled

You already have 3 drives at location 1.2, 1.17 and 1.18. Out of them you need to just replace 1.2 as that one failed.

Then  you need another 11 drives of 600 Gb each. so that  you can create Virtual Disk Group 7 x 600 GB =4200 Gb drives in each Pool.

Otherwise you can take data backup, then delete all data and existing disk-groups. Then re-create VDG and volumes. After that you can convert them as Thick Volume means overcommit option you can disable by modifying Pools settings.

 

Hope this helps!
Regards
Subhajit

I am an HPE employee

If you feel this was helpful please click the KUDOS! thumb below!

***********************************************************************************


I work for HPE
Accept or Kudo