Can somebody help me clarify the following noob questions on symmetrix. I have been into netapp storage world for many years and recently started getting into EMC storage environments.
Que 1) If I introduce a few new disks in to an emc symmetrix, how will I create hypers on each disk? What are the factors that i should consider for determining the number/size of hypers per disk.
If I introduce 5 disks, can those 5 disks have different hyper count? I mean 1st disk 8 hypers, next 10, next 12 etc
Once the hypers are defined on a disk is it possible to change the number of hypers on it. Just for understanding - So its okey even if it means wiping all the existing data on the disk.
Que 2) What is the difference between a device and a logical volume?
I already looked around for an answer on the web. But could not find a clear answer.
Assuming your VMAX is using thin provisioning...
You would create TDAT volumes on the empty disks. 8 hypers per drive (more if the drives are too big to create 8 at maximum volume size). 8 is for performance reasons. Use a size that will completely fill the drive so as not to waste space (all the same size). You would typically fill the drives with TDAT volumes, regardless of when you use them.
By a raid group, all drives will have the same volume count on them. Typically all drives of the same speed and capacity will have the same config... there are exceptions of course. Two different thin pools on the same disk types for example.
You will introduce disks in line with your RAID type. So multiples of 4 drives for Raid 5 3+1 (there is the odd SPARE drive that needs to be added too. Your local account team will sort that out for you.
A device and logical volume are really the same thing. I will also throw in symdev and its the same thing too. Not all logical volumes are host presentable though... there are different types.
The "tags" in the post say DMX, so it might not be virtual provisioning. In that case you may be creating thick volumes. With either thick or thin, when you create a volume on the disk, it has protection (RAID1, RAID5, RAID6, etc) and will span some number of drives depending on the protection. One backend volume will be one logical volume. With VP, you have a backend TDAT logical volume (data pool device) and a front end logical device that the host sees that uses the data pool.
With thick (or even TDATs) you CAN mix raid types on a disk, but it is NOT recommended.
Knowing if you are using TDEVs (VP) or not would be helpful.
Thanks for the replies. My query was from a DMX context and thick volumes. May I also know a few symcli commands for managing hypers?
1) symdisk show <disknumber> will show you the hypers on each disk.
2) symdev list will show you all the device created.
3) symdev show <devnum> will give you the details of each symdev
anything you are looking for in particular?