topic Re: Trying to understand Smart Array 5i - array, logical drives,... in ProLiant Servers (ML,DL,SL)

Trying to understand Smart Array 5i - array, logical drives,...

Jim Lum — Sat, 21 May 2005 12:04:23 GMT

Hi,

I am working with a Proliant DL350 (I think) with 2 73GB SCSI drives, and the Smart Array 5i controller.

Originally, this system was configured with both physical drives in a single ~69GB logical drive, RAID 1+0.

I am doing some testing with some partitions and partition imaging, and so this week, I used APCU to migrate the logical drive to a single physical drive, RAID 0, so the 2nd physical drive was not assigned to any logical drive.

When I booted the system, and went into ORCA, it seemed to show that the logical drive still used both drive 0 and drive 1, so I booted into Windows 2000, and started APCU. APCU showed one logical drive with 1 physical drive, and the 2nd drive unassigned.

So that's my 1st question: Why did ORCA seem to show both physical drives in the one logical drive, whereas APCU correctly showed only the 1 physical drive in the logical drive?

Anyway, so then I used APCU to create a 2nd logical drive RAID 0, with just the 2nd physical drive.

I used a partition imaging utility (BootitNG or "BING") to make a copy of the C: partition from the 1st logical drive to the (new) 2nd logical drive. I also marked the copied partition on the 2nd logical drive as Active.

I then powered the system down and physically removed the 1st physical drive, and then powered the system on. I was expecting that the system would just boot off of the copied system partition on the 2nd physical/logical drive, but during the boot, there was a msg saying that the drive 0 was missing. I pressed F2 (I think) to continue and booted into BING.

However, when I went into BING, I could see the 2nd drive, but there was no partitions on it.

I then powered the system down, plugged in the 1st drive again, and powered back on, booting into BING.

This time, BING showed the original partitions on the 1st drive, and the copied partition on the 2nd drive.

Here is the question that I have:

- I now have two logical drives. Each logical drive consists of 1 physical drive. Both logical drives are RAID0.

- With the way that that Smart Array 5i works, are both of these logical drives somehow still "tied together"? What I mean by this is that I only seem to be able to use the system if both physical drives are physically plugged into the system.

I hope that someone here can clarify some of this, as I am a bit confused :(...

Thanks,
Jim

Re: Trying to understand Smart Array 5i - array, logical drives,...

Jim Lum — Sat, 21 May 2005 13:40:29 GMT

Hi,

I've been doing some more reading/research, and I'm thinking that perhaps instead of creating the 2nd logical drive with the 2nd physical drive, I should have created a new array, then created a RAID 0 logical drive with the 2nd physical drive in it.

Comments?

Jim

Re: Trying to understand Smart Array 5i - array, logical drives,...

Jim Lum — Sat, 21 May 2005 21:25:22 GMT

Hi,

I was going to try again, and this time, wanted to create a new array, so that I could add the 2nd physical drive as a logical drive in the new array.

However, the ACU utility doesn't offer a way to create a new array. According to the Help, it says that the 5i controller should support up to 32 arrays, but I can't find any options in the utility to "Create an array".

Can anyone tell me what's wrong, or how I can create a new array?

Thanks,
Jim

Re: Trying to understand Smart Array 5i - array, logical drives,...

Colin_29 — Sun, 22 May 2005 02:43:19 GMT

Jim,

I'm not sure where you are going with this but you need to understand the basics of hardware array controllers.

Whatever logical disk you configure at hardware level is effectively presented to the OS as physical disks.

At the hardware level, you can add physical drives but you cannot take them away. You can convert between different RAID configurations whithin limitations.

If you need to take a drive away from an array (such as revert from RAID1 over two drives to RAID0 on one) then you would need to delete the array and create a new one.

When you removed one of your drives, you did so without reconfiguring at hardware level, hence the array controller warned you that a drive was missing from the mirror and invited you to continue by failing that missing drive.

Does this make things a bit clearer?

Colin

Re: Trying to understand Smart Array 5i - array, logical drives,...

Jim Lum — Sun, 22 May 2005 09:34:34 GMT

Colin,

Thanks for the response.

If I'm understanding what you said, at this point, the only way that I could remove the 2nd physical drive from the (currently one and only) array would be to:

1) Delete the current array, then

2) Create a new array with just the 1st physical drive, and create a RAID0 logical drive with just the first physical drive, then

3) Create a new 2nd array with just the 2nd physical drive, and create a RAID0 logical drive with just the 2nd physical drive

And the above would leave me with:

Two arrays, each with one logical drive, where each logical drive consists of a single physical drive in RAID0.

At that point, both physical drives would be essentially "independent" of each other.

Is that correct?

Can the above be done non-destructively, or would it destroy the data on both physical drives?

Jim

Re: Trying to understand Smart Array 5i - array, logical drives,...

Colin_29 — Sun, 22 May 2005 09:40:47 GMT

Jim,

Yes that is correct and unfortunately it is a destructive process.

Colin

Re: Trying to understand Smart Array 5i - array, logical drives,...

Jim Lum — Sun, 22 May 2005 09:43:46 GMT

Colin,

Ok, that's what I thought...

Jim

Re: Trying to understand Smart Array 5i - array, logical drives,...

Colin_29 — Sun, 22 May 2005 09:52:56 GMT

Jim,

There are some good whitepapers on the HP site and the old Compaq site. For example this one on RAID expansion http://h200005.www2.hp.com/bc/docs/support/SupportManual/c00257511/c00257511.pdf. It's worth a delve around to see what you can pick up.

Good luck
Colin

Re: Trying to understand Smart Array 5i - array, logical drives,...

Ernest Ford — Sun, 22 May 2005 11:24:51 GMT

Actually, I think an better understanding of the RAID concept should be the first step.

http://www.pcguide.com/ref/hdd/perf/raid/

I'm seeing suggestions of RAID arrays configurations that are just not possible - as an example, Jim's first post speaks of a RAID 1+0 with 2 physical drives.

With only 2 physical drives, you can only create a RAID 0 array OR a RAID 1 array - a RAID 1+0 array needs a minimum of 4 physical drives, since what you're going to do is create a RAID 0 array using the two RAID 1 arrays.

RAID 0, which has no redundancy, is created by writing "stripes" to as many disks as you have available, is done to achieve speed, and capacity. You can create a RAID 0 array with as many disks as you can connect to the controller, with the minimum being 2

RAID 1, (also known as mirroring) which has 100% redundancy, is created by writing the same data to both disks. It's prime purpose is redundancy, secondary purpose is speed. A RAID 1 array requires 2 disks.

Re: Trying to understand Smart Array 5i - array, logical drives,...

Jim Lum — Sun, 22 May 2005 11:46:22 GMT

Ernest,

A couple of points:

1) Awhile ago (not on this thread), I asked how to create a logical drive with the 5i controller with just one physical drive. The answer that I got was that the only way to do this was to create a RAID0 logical drive with just 1 physical drive. When you try to configure a "RAID1+0" in ORCA, you have to select at least 2 physical drives. Selecting RAID0 is the only choice that allows you to select only 1 physical drive.

2) If I recall, when you create a logical drive using ORCA (I'm not sure about ACU, I hadn't used it at that time), it only offers you two choices:

- RAID0
- RAID1+0

Now, originally, this system was configured with one logical drive (with the 2 physical drives in it, in the one array), and both ORCA and ACU showed the logical drive as RAID1+0.

My desire was to separate the 2 physical drives, and so I used ACU to migrate that logical drive to a RAID0 logical drive with a single (the 1st) physical drive.

After the migration using ACU, what I ended up with was one logical drive, consisting of the 1st physical drive only (which is what I wanted) and the 2nd physical drive was still in the array, but showed as unassigned or unallocated in ACU.

I then used ACU to create a 2nd logical drive (in the same array) consisting of the 2nd physical drive only.

After that point, I now have one array, with two logical drives. Both logical drives are RAID0, and each logical drive consists of one physical drive.

This is all a bit confusing :(. I'm somewhat aware of RAID levels. Maybe the terminology that HP/Compaq uses in their tool(s) is not "normal", but the above is what I did, and what I see in those tools cited.

Jim

Re: Trying to understand Smart Array 5i - array, logical drives,...

Colin_29 — Sun, 22 May 2005 13:23:52 GMT

Ok,

I was kind of hoping that Jim would have a dig around. Teaching RAID technology and terminology over a forum is not the best of ideas, but take a look at these other links:

http://docs.hp.com/en/5990-8172/apas03.html

http://h18004.www1.hp.com/products/servers/proliantstorage/arraycontrollers/adg/

http://docs.hp.com/en/J6369-90011/apbs02.html

As you will see from the above links Ernest is right in his comments. I also agree with Jim's comments that HP do seem to get terminology a bit confused within some of their utilities.

So Jim the bottom line is a bit of reading.

Regards
Colin