EVA4400-Best practices

[Derar_1]

Hello All.....

I Have EVA4400 with 8 Disk Enc
The Fisrt Disk Enc have 5 Disk with 600GB and 6 Disks with 300GB
The Other Seven Disks Enc each have 3 Disk with 600GB and 8 Disks with 300GB

total of 28 Disks with 600 GB,62 with 300 GB.

I need to have 4 Disk Groups what is the best practices in this Case ???

[Sivaramakrishna_1]

Hi,

The performace depends on the number of drives in DG also.

Generally single DG will perfom better and here as mixed size HDD, I would prefer 2 DG (one is of 300GB DG and second is of 600GB) which is the one of the best choice..

Inorder to create seperate DG for 300 and 600, it may require to remove the all 600GB drives from array and initialize with 300 GB drives, then insert all Disks of 600 GB one by one. Later you can create a seperate DG of 600GB HDD

[Johan Guldmyr]

Hi, yeup, for best performance you should use as few disk groups with as many disks in them as possible.

Why do you need four disk groups?

[Don Mallory]

I suspect you are trying to split your databases and transaction logs for SQL or Exchange between two disk groups for redundancy and/or performance.

Redundancy yes-if.., performance, not so much on a 4400.

Because the 4400 is a single redundant loop architecture, this won't benefit you. On an EVA6k or 8k, where it's a switched set of loops, you would see more benefit. Same on an EMC CLARiiON array, ut the 4400 won't benefit from this.

What it will do, is segregate the data, so if you were to lose an entire DG, which, although doesn't technically occur (often), could occur, and on other HP arrays, I have seen it occur, you would either lose the DB or TL data sets. That said, because it's all shared loops, it won't really matter, you'd be back to backups and/or snapshots/replication destinations anyways.

Your problem is going to be performance. 14 spindles at 600GB, you are going to find will run very slow, and even if you short provision the disk (only use 146GB of each disk), it won't really help because you have too few spindles. Given your 4 DG requirement, and likelihood that it's datases, you will also be applying small block I/O loads, which will significantly benefit from more spindles. If it was all large block I/O, you might be able to get away with it to a limited degree.

You also can't get full shelf redundancy in your config. This is one of the misnomers of flexible deployment architectures. It's nice to be able to add disks of many sizes, but without enough spindles or shelves, you might as well not have bothered.

Given your low spindle count I have to concur with the others and suggest two disks groups, one of 300's and one of 600's. If you really must split up the 300's fine, but leave the 600's one group.

For deployment, if you're blanking the array anyways, I agree with pulling the 600's and build a DG, then insert one at a time. If you shutdown the array, you can technically add full shelves of disks all at once, then boot, but it's not the most recommended situation.

Personally, I always liked having DG1 on the left and DG2 on the right, splitting more spindles across shelves, but also allowing me to quickly assess which DG was affected during a disk failure. If you use the tool in CommandView to create 2 DGs on initialisation, it will do this for you automagically.

Good luck.
Don

[Johan Guldmyr]

Wish I could give points, you'd get a million from me Don :)

[Derar_1]

Hi All ,

Thanks alot for your Replay...

I think i will have 2 DG (one is of 300GB DG and second is of 600GB) which is the one of the best choice.

Now

Step1- I will remove the 600 GB Disks form
the 8 Enclosures start from UP to down

ENC8 have 5 Disks(Bay1,Bay2,Bay3,Bay4,Bay5).
ENC2 Have 3 Disks(Bay1,Bay2,Bay3).
ENC6 Have 3 Disks(Bay1,Bay2,Bay3).
ENC7 Have 3 Disks(Bay1,Bay2,Bay3).
ENC1 Have 3 Disks(Bay1,Bay2,Bay3).
ENC3 Have 3 Disks(Bay1,Bay2,Bay3).
ENC4 Have 3 Disks(Bay1,Bay2,Bay3).
ENC5 Have 3 Disks(Bay1,Bay2,Bay3).

"This Enc Order is Mentioned in the back"



Step2- I will Create the Defualt DG for 300 GB.
which will have (58) Disk.



Step 3-Then I will return the 600 GB Disks One By One ie from Up to Down

ENC8-Bay1 Add it to the second Disk Group
ENC2-Bay1 Add it to the second Disk Group
ENC6-Bay1 Add it to the second Disk Group
ENC7-Bay1 Add it to the second Disk Group
ENC1-Bay1 Add it to the second Disk Group
ENC3-Bay1 Add it to the second Disk Group
ENC4-Bay1 Add it to the second Disk Group
ENC5-Bay1 Add it to the second Disk Group

Step 4-
ENC8-Bay2 Add it to the second Disk Group
ENC2-Bay2 Add it to the second Disk Group
ENC6-Bay2 Add it to the second Disk Group
ENC7-Bay2 Add it to the second Disk Group
ENC1-Bay2 Add it to the second Disk Group
ENC3-Bay2 Add it to the second Disk Group
ENC4-Bay2 Add it to the second Disk Group
ENC5-Bay2 Add it to the second Disk Group

Step 5-
ENC8-Bay3 Add it to the second Disk Group
ENC2-Bay3 Add it to the second Disk Group
ENC6-Bay3 Add it to the second Disk Group
ENC7-Bay3 Add it to the second Disk Group
ENC1-Bay3 Add it to the second Disk Group
ENC3-Bay3 Add it to the second Disk Group
ENC4-Bay3 Add it to the second Disk Group
ENC5-Bay3 Add it to the second Disk Group

Step 6-
ENC8-Bay4 Add it to the second Disk Group
ENC8-Bay4 Add it to the second Disk Group



Are these is the Right steps and Am match the Best Practice....

[Don Mallory]

That would be a fine config. The problem is that you would never have full shelf redundancy, partially because of the number of disks involved and partially how HP sets up it's RSS groups (8 disk groups.. it's an odd algorithm at best.)

So it may not actually matter that they are on different shelves. Personally, I'd do it anways. A little foresight in design goes a long way on an unexpected bad day.

Thanks for the vote of confidence Johan!

Don

[Derar_1]

Hello All,

I started to remove all the 600GB disks from their shelfs,but once i power up the system cant recognize the Controllers,Arrays.

So i return Back the 600 GB disks to their shelfs.

i created The Default Disk group of 8 Disks and the system reserve these 600GB Disk randomly from
(Enc8,Bay4),(Enc2,Bay2),(Enc6,Bay1),(Enc7,Bay2),(Enc1,Bay3),(Enc3,Bay2),(Enc4,Bay3),(Enc5,Bay2).

then i add all the (18) 600GB to this Default Disk group...

Then i created the Second disk group and added to it the 58 disks with 300 GB.

As a best practice
Now i have 26 Disk with 600 GB in this Group.
and the Second have 58 Disk with 300 GB.


Thanks to you all,and Happy Hoilday :-)

Yes we are One team.....
Engineer Derar.