VMAX 10k Hot spares

Question

I have a question regarding Hot spares and how many we need.

We are currently running enginuity 5876.229.145 on a VMAX 10k

Our current configuration is:

Thin pools:

RAID-5 (7+1) bound to Disk Group 002 600GB SAS 15k 24 disks plus 2 spares

RAID-6 (6+2) bound to Disk Group 001 2TB SATA 7.2k 32 disks plus 2 spares

We also have Disk Group 003 600GB SAS 15k 8 disks no spares.

What we'd like to do is create an additional disk group (004) with (8) 2TB SATA 7.2k disks - would we need additional disks for spares or can the spares from disk group 001 be utilized?

Also, we'd like to add (8) 600GB SAS 15k drives to disk group 003. Same question - would we be able to utilize the spare disks in disk group 002 for this or would we need additional spares?

If we need additional spares - how many?

Thank you,

Jim

AranH1 · Answer

The spares are global for each disk model, they are not aligned to the disk group only.

IMO you will be better off expanding existing disk groups and pools then rebalancing the extents across the new DATA devices. I doubt that with having multiple pools of the same drive and RAID type that DRS will be able to tell the difference between the two.

Quincy561 · Answer

Just wondering why not add the 8 600GB 15k drives to the existing disk group?

jgregory419 · Answer

All of these thin pools are being pointed to a shared vmware infrastructure. We are trying to diversify our storage a bit and be able to utilize DRS to move VMs effectively between diskgroups while maintaining the same disk technology. Right now, all of our VMware LUNs are striped across the same disks, by adding disk groups, we can storage vmotion to a different disk group to help balance the workload while maintaining disk technology.

Essentially, we want to be able to offload some of the workload to a different set of spindles.

Quincy561 · Answer

8 spindles won't handle much workload.  Figure max of 150 IOPs per disk, so 1200 total IOPs.  If these are writes and you go raid5, that is only 300 host IOPs.  600 host write IOPs if raid1.  Just make sure these 8 drives can handle the load you want to put on them, or they could adversely impact all the workloads on the box.

M_Salem · Answer

I believe you meant Storage DRS not DRS. For this purpose you first implement VMware VASA for Symmetrix and then you create storage profiles for your datastores afterwards you create Datastore clusters from datastores of same technology. Enabling Storage DRS on this cluster will balance the VMDKs of your VMs across the datastores of same technology.

Enabling FAST VP on SYMM will definetly add a great value to the above solution.

Hope that helps

Mohammed Salem @yankoora

MelbSteve · Answer

To answer your question on spares.

Spare disks are required based on the total number of each type of disk in the system.

The basic rule is 2 spares per 100 disks of each type.

For your disk group 2, (24 x 600Gb 15K + 2 spare) if this is the total quantity of 600Gb 15K then adding 8 more would not take you above 100 disks of this type.

Steve

sauravrohilla · Answer

SRDS is not recommended when you have FAST VP enabled, especially when VM is IO intensive.. regards, Saurabh

M_Salem · Answer

SDRS is supported with FAST VP however, We support this based on capacity balancing only without considering IO or performance metrics for balancing. This has been detailed in Cody & Drew awesome techbook (v 9.0)

https://support.emc.com/docu33910_TechBook:-Using-EMC-Symmetrix-Storage-in-VMware-vSphere-Environments.pdf?language=en_US

You will find this mentioned in page 209

For IO intensive VMs you can exclude SDRS from controlling these VMs.

Hope that helps

Mohammed Salem. @yankoora

sauravrohilla · Answer

ok, thanks for clarification

VMAX

VMAX 10k Hot spares

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