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SCSI connectors and RAID levels on the ML350

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Erik Bak
Occasional Visitor

SCSI connectors and RAID levels on the ML350

I am in the process of buying a server, probably an ML350.

The server will be acting as file/print server and will be running Exchange server and SQL server and have a maximum of 10 simultaneous users.

I would like to configure it something like this:
2 x 36GB in RAID1 configuration.
3 (or more) x 36GB in RAID5 configuration.
1 x 36GB as a hot spare.

Is this possible and advisable?
(According to the specs, the ML350 comes with a "Dual Channel Wide Ultra3 SCSI Adapter" and a SA641 RAID controller but I have not been able to find information on the SA641).

Furthermore, I want to be able to attach a newly purchased HP DAT72 external tape drive to the server. This tape drive is Ultra160 SCSI.
Will that work well?

Is the ML350 the right server for this purpose after all?

Best regards
Erik
11 REPLIES
Vijay_44
Honored Contributor

Re: SCSI connectors and RAID levels on the ML350

With the SA641 you can configure your hdd as you have mentioned above. The server can take 6 hot plug drives in its drive cage. The DAT drive can be connected to the scsi controller.
There’s your problem!!! This thing is set to EVIL!
Erik Bak
Occasional Visitor

Re: SCSI connectors and RAID levels on the ML350

Hi again,

I now realize that the SA641 is only one channel, so this will not allow for having RAID1 and RAID5 at the same time.

So, I guess what I need is a ML350 with a dual channel SCSI adapter and an SA642 RAID controller (dual channel) instead. Would this configuration allow me to have an external tape drive along with the RAID1/RAID5 combination that I want?

Best regards,
Erik
Eric_76
Regular Advisor

Re: SCSI connectors and RAID levels on the ML350

you can still do what you need using one channel.
Prashant (I am Back)
Honored Contributor

Re: SCSI connectors and RAID levels on the ML350

Hi,

Hi Vijay is right we can have raid1 and raid5 on once channel also. Go through the following user guide it will help you explaing the ACU used for manuplating and creating raid on server. So can get brief idea abou the RAID on Proliant servers. Where as feature are controller specifics only.

ftp://ftp.compaq.com/pub/supportinformation/techpubs/user_reference_guides/239449-004_rev4_us.pdf

regard,
Prashant S.
Nothing is impossible
Vijay_44
Honored Contributor

Re: SCSI connectors and RAID levels on the ML350

Eric the SA642 is a 2 channel controller but one is external and one internal.
There’s your problem!!! This thing is set to EVIL!
Gordon Leonard
Honored Contributor
Solution

Re: SCSI connectors and RAID levels on the ML350

I suspect your configuration could be optimized in regards to the RAID setup. I'm assuming you're using the RAID 1 for the OS and swap file and the RAID 5 for everything else. This mean you're going to be wasting a lot of space and have less performance. How much space do you really need on the RAID 1?
Erik Bak
Occasional Visitor

Re: SCSI connectors and RAID levels on the ML350

Hi Gordon

You're right, the RAID1 will primarily be used for the OS (Windows 2003).

The server will be running SQL Server and Exchange Server, and Terminal Services will be enabled (all users will be running thin clients).

Would it be advisable to have the SQL database on the RAID5 and the SQL logfiles on the RAID1 ?

Do you have any suggestions on how I could set up the server in a better way?

Best regards
Erik
Gordon Leonard
Honored Contributor

Re: SCSI connectors and RAID levels on the ML350

The general rule for SQL is to place the log files on a RAID 1 set. However with only 10 people on the server this may be over kill. Understand I don't how this SQL server is being used.

But consider this - The bottleneck in storage is the drive. To maximize through-put you add spindles (hard-drives).

On the Smart controllers you can create virtual RAID sets - ONLY HP Smart RAID controllers can do this no other vendor can do this!!!

Ground rules:

1. Stop thinking of RAID sets as drives in a set. I mean it, stop it right now.
2. To do this you need to use an EVEN number of drives (don't count the hot spare).
3. The drives must be the same size.

For example.

I need 8GB of RAID 1 and 96GB of RAID 5.

I would use four drives (see rule #2).

Place all the drives in an array (array 'A').
This will create the total raw storage of (4x36) 144GB.

Create a logical drive that's 8GB in size RAID 1 (this will use 16GB of RAW space thus 144-16=128).
Create a logical drive that's 96GB in size RAID 5 (this will use 128MB of RAW space thus 128MB RAW / 4 Drives = 32MB, The overhead for RAID 5 is the space of one drive so 3x32=96).

Doing this has just maximized the spindle count for both RAID sets.

Something to think about.
Erik Bak
Occasional Visitor

Re: SCSI connectors and RAID levels on the ML350

> Doing this has just maximized the
> spindle count for both RAID sets.
> Something to think about.

I think I get the point. But your solution rises a new question: How does the concept you suggest (i.e. using "virtual RAIDs") affect the server's ability to withstand failing disks?

Since each and every disk participate in the array and thereby also in the RAID1/RAID5, a failing disks will affect both RAIDs - or ...?

Best regards,
Erik
Gordon Leonard
Honored Contributor

Re: SCSI connectors and RAID levels on the ML350

Probability of failures is noted in the document (link provided in this tread).

"Since each and every disk participate in the array and thereby also in the RAID1/RAID5, a failing disks will affect both RAIDs - or ...?"

YES

A physical disk failure causes the system to be in a degraded state regardless if the physical disk was supporting a single or multiple RAID sets. Your protective measures should be the same by utilizing a hot spare and using IM7 or SIM to detect predictive fault issues (this means detect the problem before the actual fault occurs).
Erik Bak
Occasional Visitor

Re: SCSI connectors and RAID levels on the ML350

Thank you all.

The information and hints you have supplied have been very valuable to me.

Best regards,
Erik