topic SAN Disk space in MSA Storage

SAN Disk space

Aamir14 — Fri, 01 Nov 2013 12:45:13 GMT

Hi'

I have eva4400 san and its has 36 harddisk 146*36=5256

But EVA software Shown

This storage system is 84% allocated

Total: 4642 GB Allocated: 3894 GB Allocation level: 84 % Available: 747 GB Requested: 0 GB Oversubscribed:

total 4642

but its actual 5256

Why its shown 4642 ?

I know its raid configure

So,

What is a formula to get this value 4642 ?

and how to see disk utilization graph value ?

Thanks

Aamir

Re: SAN Disk space

Torsten. — Fri, 01 Nov 2013 13:12:27 GMT

I'm sure you set the protection level of the diskgroup to "double" - this reserves the space of 4 disks.

From online help:

Disk failure protection levels

The disk failure protection level determines the amount of storage space that is reserved in a disk group for data reconstruction if physical disks in the group fail. The reserved space is not a number of physical disks. It is the equivalent amount of storage space spread across all disks in the disk group. The disk failure protection levels are:

Single failure protection. Reserves space within a disk group for data reconstruction if 1 disk fails. The disk group can lose 1 physical disk and maintain the redundancy (Vraid) levels in the group.
Double failure protection. Reserves space within a disk group for data reconstructions if 2 disks fail. The disk group can tolerate the loss of 2 physical disk and maintain the redundancy (Vraid) levels in the group.
None. Reserves no space within a disk group for data reconstruction in case a disk fails. The disk group cannot tolerate the loss of any physical disks and maintain the redundancy (Vraid) levels in the group.

IMPORTANT: HP recommends the use of single or double protection rather than None.

Re: SAN Disk space

Aamir14 — Fri, 01 Nov 2013 20:11:39 GMT

Hi,

Very helpful answer.

Its mean When I manually open two hard disk at same time on SAN

Its recover ?

whether both two hard disk are attached on single eight drive shelve

or any different-different another disk shelves.

its recover?

thanks

aamir

Re: SAN Disk space

Torsten. — Fri, 01 Nov 2013 20:19:13 GMT

>> The disk failure protection level determines the amount of storage space that is reserved in a disk group for data reconstruction if physical disks in the group fail

This is reserved space, not available for storing data, just used for data recovery if a disk fails.

It does NOT mean 2 disks can fail at the same time. To protect this case, create a vraid6.