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Raid 1 with different disk sizes

Jorge HP
Advisor

Raid 1 with different disk sizes

Hello people,

Proliant ML150 G5, HP Embedded SATA RAID Controller (RAID 0,1,10), 2 SATA hard disk, of
160 and 250 Gb, is it possible to create a Raid1??,
HD 160 Gb in port 0, and HD 250 Gb in port 1???

thanks in advance
10 REPLIES
Pieter 't Hart
Honored Contributor

Re: Raid 1 with different disk sizes

In theory no problem.
Done this with SCSI
Not done it with SATA.

max size will be limited to 160G!!
MSECO
Frequent Advisor

Re: Raid 1 with different disk sizes

Hi Jorge:



Please check the next document:



http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00771065/c00771065.pdf

RAID 0

The size of a drive segment is the size of the smallest disk drive in the array. For instance, an array that consists
of two 250-GB disk drives and two 400-GB disk drives has a drive segment size of 250 GB. This array thus has
1,000 GB (= 4 x 250 GB) of usable drive space, all of which can be used to store data when the array is used
to build a RAID 0 logical drive. The array also has 300 GB of drive space that is unusable in the context of this
particular collection of drives.

RAID 1
If a RAID 1 array is built from different-sized disk drives, the size of the drive segment is the size of the
smaller disk drive, as with RAID 0.
Keep learning!!!
adnanmaliq
Visitor

Re: Raid 1 with different disk sizes

Hi Jorge
In above scenario is it possible to use  the extra space left on bigger drive "300 GB of drive space that is unusable" ? If so then how ? and is it possbile to do it online(while system is running, using hpacucli etc) ?

My scenario : 
Server : ProLiant BL460c Gen8
Model : HP Smart Array P220i Controller
Logical Drive 01 : 136 GB , Fault Tolerance : RAID 1/RAID 1+0
             Physical Drive in Port 1I Box 1 Bay 1 -->        Capacity: 136 GB, 
             Physical Drive in Port 1I Box 1 Bay 2 -->        Capacity: 558 GB, 

So i am getting 136 GB space in OS. How can I use the remaining space from physical disk 2 : Space : 558-136 =422GB
I want to use this 422GB. It might sound strange and I am aware of the fact that this part of the disk will not be using RAID 1.

I will really appreciate quick replies. 

Adnan Malik

Dennis Handly
Acclaimed Contributor

Re: RAID 1 with different disk sizes

>In above scenario is it possible to use the extra space left on bigger drive?

 

I don't think you can.  The OS can't see that part unless the controller allows these "left over" pieces.

adnanmaliq
Visitor

Re: RAID 1 with different disk sizes

" The OS can't see that part unless the controller allows these "left over" pieces." 

and how to allow in controller ? 

Dennis Handly
Acclaimed Contributor

Re: RAID 1 with different disk sizes

>and how to allow in controller?

 

That's the problem, I don't think it can.  Especially since this isn't a normal situation.

Jimmy Vance
HPE Pro

Re: RAID 1 with different disk sizes

You can use any disk same size or larger than the smalles disk in the array. The array will only use whatever size the smallest disk in the array is. All 'extra' space is wasted and unusable. The only option is to change out all of the disks to the same size as the largest disk (one at a time). Once the array has rebuilt (between each disk swap) you can then expand the array to reclaim the unused space

 

Standard disclaimer:

Always have a good backup before you start messing around with your disks or arrays

 




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adnanmaliq
Visitor

Re: RAID 1 with different disk sizes

Yes i know that, But that does not answer my question :)


Adnan

Jimmy Vance
HPE Pro

Re: RAID 1 with different disk sizes


adnanmaliq wrote:

Yes i know that, But that does not answer my question :)


Adnan


My comment

"The array will only use whatever size the smallest disk in the array is. All 'extra' space is wasted and unusable" doesn't answer your question?




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adnanmaliq
Visitor

Re: RAID 1 with different disk sizes

>"The array will only use whatever size the smallest disk in the array is. All 'extra' space is wasted and unusable" doesn't answer your question?

 

Please excuse my earlier comment and allow me to re-phrase it. Your answer does answer my question but it does not resolve my problem of using that extra space. This is probably because it is not possible to use that extra space, as you and Dennis said already.
Thanks for the quick responses everyone.

Adnan