3Par Usage / Capacity / Provisioning for Dummies..

[walter_white]

I come from an EMC background and trying to wrap my head around how 3Par does their provisioning has my head spinning and making me feel super dumb..

I'm used to thick provisioning as well and we use all thin at my current job..

So in EMC you create the storage pool (4+1 or 8+1 RAID5 with 10K/15K, 6+2 or 8+2 RAID6 with NL-SAS/7200).. After that you provision the LUN/Datastore (I work strictly with VMWare) and then you see it in VMWare..

I can easily see how much space is left on the SAN side and the VMWare side..

With 3Par, I cannot wrap my head around CPGs, estimated maximum CPG size, capacity used vs free, etc..

As a storage guy I would think one of the most important things is "Do I have enough?" and for the life of me, I can't easily see that in StoreServ..

Hopefully someone can help me out.. I even took HK902S: Managing HPE 3PAR StoreServ I and HK904S: Managing HPE 3PAR StoreServ II and the instructor didn't even go over capacity!!

Thanks for any help and hopefully I don't get laughed off the forum..

[Noss]

I think the first thing to understand is an EMC Storage Pool is not the same as a 3PAR CPG. Where with Storage Pools you are physically allocating space to be able to create volumes from, a CPG is just a template, with rules on how to organise data (in 1GB Chunklets) across physical drives. When you first initially create a CPG, it doesn't allocate any space.

What capacity is available via your CPG depends what settings you have on it. E.g. Disk Type, Set Size. The CPG will only draw from that space on a need basis determined by growth increment and volume usage within the CPG. Capacity(chunklets) not required and free can be used for other CPGs if it matches the same disk type. Hence why the same physical drives can support different RAID types.

The CPG estimated maximum size figure is based on the capacity available if you were to continue drawing space from it using the same CPG template. Though remember, other CPGs could be using the same available space.

The CPG capacity used figure is based on what has actually been allocated to that CPG for use of volume space and cannot be used by anything else.

The CPG free figure is the space available from what has been allocated to the CPG and volume data written.

If more space was required in the CPG to allow for volume growth, then more capacity(chunklets) would allocated to support it. Allocation size is controlled by the Growth Increment settings

The showsys -space cli command will show you a Free Initialized figure. This is available to existing/new user/copy CPGs.

Unfortunately, Managing HPE 3PAR StoreServ III goes into detail about capacity.

[MammaGutt]

If I'm not completely mistaken you are even allocating physical drives in the EMC Storage pool. So you are only getting the performance on the drives allocated to the pool.

I would suggest looking into the HPE 3PAR StoreServ Storage Concepts Guide

https://support.hpe.com/hpsc/doc/public ... =c04204225

This covers a lot and if there is something there that isn't clear just ask

[walter_white]

I think the first thing to understand is an EMC Storage Pool is not the same as a 3PAR CPG. Where with Storage Pools you are physically allocating space to be able to create volumes from, a CPG is just a template, with rules on how to organise data (in 1GB Chunklets) across physical drives. When you first initially create a CPG, it doesn't allocate any space.

What capacity is available via your CPG depends what settings you have on it. E.g. Disk Type, Set Size. The CPG will only draw from that space on a need basis determined by growth increment and volume usage within the CPG. Capacity(chunklets) not required and free can be used for other CPGs if it matches the same disk type. Hence why the same physical drives can support different RAID types.

The CPG estimated maximum size figure is based on the capacity available if you were to continue drawing space from it using the same CPG template. Though remember, other CPGs could be using the same available space.

The CPG capacity used figure is based on what has actually been allocated to that CPG for use of volume space and cannot be used by anything else.

The CPG free figure is the space available from what has been allocated to the CPG and volume data written.

If more space was required in the CPG to allow for volume growth, then more capacity(chunklets) would allocated to support it. Allocation size is controlled by the Growth Increment settings

The showsys -space cli command will show you a Free Initialized figure. This is available to existing/new user/copy CPGs.

Unfortunately, Managing HPE 3PAR StoreServ III goes into detail about capacity.

So I have a CPG that is used for all my volumes on one of my 3Pars..

FC_r1: Fast Class 10K / Raid 1..

Used: 1,726 GiB
Free: 50 GiB

Growth limit: 2,458 GiB
Estimated maximum CPG size: 2,150 GiB

When I look at all the volumes in that CPG and add up the "Total Used" it is the 1,726 GB.. How am I to easily see how much space is available in the SAN?

Thanks for the replies..

[MammaGutt]

This can be a tricky question to answer but let me try.

3PAR is a highly dynamic storage system where space is allocated when needed and in multiple layers.

The "easy" answer is to look at the "system free space" as this is capacity avilable to all CPGs on the system unless growth limits are used. Keep in mind that unlike EMC where capacity is Pre-RAIDed and allocated, the system free space on the 3PAR is raw capacity which can be allocated to any CPG at any RAID level and set size. So 10TB system free space = 5 TB net capacity in a RAID1 CPG.

The more complex answer is that you also have some free space within all CPGs. Unless something has been deleted, this is usually less than 100 GB per CPG. To make things trickier, all capacity in CPG (and VV) views are always net capacity.... so this comes in addition to the system free space, but is only available to the CPG which it is already allocated.

And even more complex you have another layer below this again where the same thing is true for VVs, but here you usually see no free space within the VV unless you've recently deleted a lot of data (or written zero blocks) so there is a reclaim going on in the background.