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RAID5 Extension

Florian Rhomberg
Occasional Advisor

RAID5 Extension

Hi,
I have a very big problem. We have an HP ML370 G4 Server with 6 harddisks (4x72 GB RAID5, 2x143 GB RAID1). Therefor I had about 208 GB on the RAID5 array and 143GB and the RAID1 Array. Now I replaced step by step all 72GB harddisks with 300 GB harddisks because we needed more space. As far as I know this should not be a problem. Then I wanted to extend the array and started the Array Configuration Utility. And there is my problem. My controller shows me at the moment two logical devices. The RAID1 array with two 143 GB and the RAID5 array with 208GB. An then there is the new free space which is not a part of an array. But the free space has only a size of 312GB and when I try to extend the existing RAID5 Array I can only get about 480 GB with four 300GB harddisks. That is nearly the half. When I click on more information there are 4x300GB harddisk listed in physical device 1.
Where is the problem? I should have about 900GB.

I hope someone can help me because it is a little bit strange to tell your boss that you bought 4x300GB harddisks and afterward you have only about 500 GB and you don´t know why.

Florian
12 REPLIES
TY 007
Honored Contributor

Re: RAID5 Extension

Hello Florian,

ML310 G4 Overview:
http://h18004.www1.hp.com/products/quickspecs/12570_div/12570_div.html

Please advise from above link, which Controller is used for the 4x300GB HDs?

Thanks
Florian Rhomberg
Occasional Advisor

Re: RAID5 Extension

Sorry I forgot to notice the used array controller. The server uses the Smart Array 641 Controller, firmeware version 2.68.

Florian
SPa
Trusted Contributor

Re: RAID5 Extension

Hi,This definitely looks strange.

If possible,post the Physical and Logical view screenshots from the Array Configuration Utility.
Florian Rhomberg
Occasional Advisor

Re: RAID5 Extension

Hi,
this is the screenshot of the utilty software. I hope this will help!

Florian
Florian Rhomberg
Occasional Advisor

Re: RAID5 Extension

And this is the view of information display:

Florian
SPa
Trusted Contributor

Re: RAID5 Extension

Hi,

I think I know the reason now.

You have all the six drives in a single array.This means the effective Physical Hard Drive space in the array is 146 X 6 .

The correct configuration would have been to have two seprate arrays.
Array A = Raid 0+1 which includes 146*2
Array B = Raid 5 which includes 300*4

Your current configuration breakup is as below :

Total Space available in Array A = 146*6 = 876 GB

Current Logical Drive 1 which is a Raid 5 has a size of 203.49 GB
Parity Size reserved for Raid 5 would be 1/3rd of the Raid 5 size which will be 67.83

Current Logical Drive 2 which is Raid 0+1 is 135.66
Mirrored Space would be the same = 135.66

If you add all of them that is 203.49+67.83+135.66+135.66 = 847.48

This is somewhat closer to the 876 Mark.The difference will be in terms of the calculation which the smart array does internally.

Overall,the difference you are getting is because of the fact that you have all the Hard Drives in a single array.The correct way would have been to have different size drives in a different array which is what the rule says that is to have same size drive in the same array else the smaller drive size is taken as the default and the more space is wasted.


chongkan
Trusted Contributor

Re: RAID5 Extension

After extensive research I can't find a reason for this behavior, the only think I could think about is that for some reason the 641 currupted the RAID 5 and teh only resolution I can think about is:

1- Back up RAID 5.
1.5 -> Upgrade firmware for the 641 to latest.
2- Turn server off.
3- Take RAID 1 (OS) HDDS out and remeber their positions ( slot positions )
4- Delete RAID 5 with ACU and recreate it. ( At this point everything should be fine ) Save all changes.
5- Turn off server again.
6- Place RAID 1 back into its original position.
7- Turn on the server. It must recognize the RAID 1 config from the HDDs.
8- Go to ACU and create logical drive for RAID 5.
9- Restore RAID 5 info.

------------------

About previous comment:

Before changing the 72 GBs drives for 300 GB drives they were a mix of 72 and 143 in the same array A. Same situation as now but with different sizes and it was working fine as it should..



SPa
Trusted Contributor

Re: RAID5 Extension

All I can say is earlier also the 146 drives would have been used as 72 GB and not 146 GB..

Recreation into a single array again with a mix of 146 and 300 GB drives will again result in the same amount of space available.You may want to try this in a spare server if available.

There should be two seperate arrays for Raid 1 and Raid 5.
SPa
Trusted Contributor

Re: RAID5 Extension

To make things more clearer

Earlier configuration was 72*4 + 146*2

Now as they were in a single array,total space available for Logical Drive creation was 580 GB(Add 72*4+146*2)

Out of which the Raid 5 space was 203.49 GB and Raid 1 space was and Raid 1 space was 135.66 .


SPa
Trusted Contributor

Re: RAID5 Extension

Looking at it again and I think Chongkan is correct.

I had my figures wrong.The original config does seems to be correct.



Florian Rhomberg
Occasional Advisor

Re: RAID5 Extension

Thank you for all the answers. I will also first update the whole system to the latest Firmeware Version. Perhaps this will solve the problem. I can´t remove the RAID5 harddisks because at the beginning we had only this array and therefor the OS is there. The two 143 GB harddisks where inserted later and they contain very sensible data therefor the RAID1. I can only notice like some of you did that after introducing the two 143 GB harddisks we were able to create a new Array with the full capacity of the harddisks.
Greetings,
Florian
Florian Rhomberg
Occasional Advisor

Re: RAID5 Extension

I updated the firmeware to the latest version without any result. I have the same problem like before. As I sad before the RAID5 Array contains the OS because at the beginning we hade only 4 72 GB hardisks the two 143 GB harddisks where introduced later when we needed more space. Does someone think it will help to remove the two 143 harddisks and afterwards starting the Array configuration utility. The system is always on power and I can´t put the server off for one day to create a new array and afterwards reinstalling and reconfigurating the whole system at the moment, this should be only the last possibility. I hope that someone has another idea.

Florian