Array configuration - one or more logical drives?

[segil]

Hello everybody,

Please help me. I've searched this website, but haven't found an anwser to my question yet. I hope somebody can help me.

We've purchased a Compaq Proliant ML350G4 with a Smart Array 641 controller and three 72 GB SCSI disks. We would like to use RAID 5. I'm not sure how to configure the array. We're going to use Windows server 2003 on this server and I want to use 3 partitions (system partition, application partition and data partition). The sizes of these partitions will be: 10-20-110 GB.
Should I create one big logical drive within the array and create the necassary partition in Windows? Or is it better to create three logical drives within the array and use these drives for the Windows partitions? Does it matter how to set it up? Which option is better for future expansion of the partition?

So my question.. Should I:

1. Create one big logical drive and create 3 Windows partitions within this drive, or
2. Create three logical drive and use each drive for a partition.

To be honest, I've never created multiple logical drives in a array, so I'm not sure it works as easy as my suggestion!

Thanks a lot for your thoughts!

Kind regards,

Russell

 

[technome]

Yes technically you could create separate "array sets" using one drive per array set, generally you define the individual drives as raid 0, which normally consists of more than one drive per array. That stated..

You do not want to do this because raid adapters are not optimized for running single disk "arrays"; a standard scsi adapter will general out perform this scenario.

Raid 5 is you better choice. Place the 3 drives in the drive bays, preferable divided over two channels. Go into the raid bios setup and select the 3 drives, choose raid 5 for the raid type. Initialize the newly created array set. Depending on the adapter the initialization may run in the background and allow you to actually start a Windows 2003 install before it complete; I would recommend you allow the process to complete before a WK2003 install. Forget about creating partition from within the raid setup; just create one large logical disk in the raid setup. Makes no sense attempting to create partitions before the Win 2003 install. With WK2003, you can easily create the first partition for the install, then go into Disk manager after the initial install, and created the remaining partitions. You will need to press F6 to install drivers for the raid when prompted at the very beginning of the Windows 2003 setup. Familiarize yourself with the raid options before proceeding, many options can be reconfigured anytime such as caching choices, others can not.

Having the OS and data on separate partitions is a wise choice. I have had corruption due to the OS rendering the system partition useless.. deleted the OS partition on purpose.. but in all cases I have never lost the secondary data partitions due to damage to the system partition. Generally go with the raid adapter default, as far as "stripe" size, which is not the same as stripe width, which refers to the number of disks in an array set. If your in Disk Manager, do not even think of making the array a Dynamic disk.

 

[segil]

Hello Technome,

thanks for your anwser... I feel relieved that I did it the right way! I configured the array with one logical volume and installed Windows on a C partition. After that the created the remaining partitions, no dynamic volumes of course!
I thought it might be a good idea to create three logical volumes within the array, so future expanstion is easy. I'm not sure what happens when I add a 4th harddisk and I assign that free space to a logical volume. Obviously that volume gets bigger, but does the Windows partition also grow automatically or must I use a partition tool to exand the partition? Because if the partition can expand and shrink automatically then it's easy to add more free space to the data partition: Simply plugin an extra harddisk, add that drive the the 3th logical volume and the corresponding partition will expand in Windows... but I guess it sounds easier then it is, right?

Well, I'm happy now with this new ML350 G4 server!

regards...

 

[thepunish3r]

Why are you not able to use dynamic disks? I have heard that there is an issue but I am not sure what it is?

 

[technome]

Why are you not able to use dynamic disks?
I did not say this.

You are able to use Dynamic disks but this adds an Os involved complexity. Bad enough no raid is invulnerable to loss, but adding Dynamic disks is an added point of failure. The only time I use Dynamic disks is with standard SCSI adapters, for mirroring or duplexing. Suppose there is Os corruption due to the OS, raid adapters are isolated from it for the most part, Dynamic disk involve many files and registry entries.