[gpfsug-discuss] Any guidelines for choosing vdisk size?

[Ryan Novosielski]

Sure; thanks, I meant to add those details:

In our case, all GSS/DSS-G with GNR.

The context here is general information, but specifically designing new filesystems/setting up one of these systems from scratch in what I’d figure to be the traditional way: don’t allocate the entire storage if you’re not totally sure the way the growth will go, but don’t leave behind unusable space or space that forces you to later change vdisk sizes. Essentially allocate something today that makes sense, but leaves room open for sensible growth with both the existing hardware and new, if expanded. If I’m thinking about this generally the wrong way, let me know.

The systems we currently own are GSS26 (6 TB drives, fully populated — I forget how many drives, 350 or so?) , and a few DSS-G 220 w/10 TB drives (also fully populated with 168 drives).

> On Jul 1, 2019, at 1:54 AM, Andrew Beattie <abeattie at au1.ibm.com> wrote:
> 
> Hi Ryan,
>  
> Can I ask a couple of clarifying questions?
>  
> Is this in an ESS / GSS environment with Scale native raid ?
> Is this in classic San attached storage environment / or Direct Attached Disk without Scale Native Raid?
>  
> What are you trying to achieve?
> Are you presenting the Vdisk into an existing filesystem ?
> Are you creating an new filesystem?
>  
>  
> Regards,
>  
> Andrew Beattie
> File and Object Storage Technical Specialist - A/NZ
> IBM Systems - Storage
> Phone: 614-2133-7927
> E-mail: abeattie at au1.ibm.com
>  
>  
> ----- Original message -----
> From: Ryan Novosielski <novosirj at rutgers.edu>
> Sent by: gpfsug-discuss-bounces at spectrumscale.org
> To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
> Cc:
> Subject: [EXTERNAL] [gpfsug-discuss] Any guidelines for choosing vdisk size?
> Date: Mon, Jul 1, 2019 3:43 PM
>  
> Good morning,
> 
> Was wondering if anyone could point me to any tips or provide some regarding choosing vdisk size? My understanding is that too small is a waste of resources in the form of overhead, and that there is an upper limit. but that generally within a pool, you want them to be the same size, so that if you aren’t allocating the entire storage space on the system straight off, you’ll need to choose a reasonable size or be left with unusable space (eg. you will waste space if you went with, say, 200 GB vdisk sizes on a 500 GB array).
> 
> Anyone have any tips? Do people just generally allocate the whole thing and have one 2 vdisks (redundancy)? Seems you have some more flexibility if you don’t do that and have to, say, create a storage pool or filesystem from scratch to take advantage of features in a newer FS version or what have you.
> 
> Thanks for the help — spent a lot of time looking for this previously, but never asked on the list.
>  
> --
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