HARDWARE RAID VS. SOFTWARE RAID

[alison gates]

Hi I have several LH Pro servers running WindowsNT - with a software Raid configuration
Raid 1 for the system partition and Raid 5 (4 HDD)for Data. Now I have serveral Netservers LH 3000 - I planning to use the NetRaid Hardware Raid - I'm trying to determine the most efficient Raid Configuration. The servers have (6 HDD) and will be used as file, web and applications servers.

I noticed that many users (in the forum) are configuring their Netservers with only one array (RAID 5). Is there any concern about system performance using only once Raid across all (HDD) Would users recommend a separate array (RAID 1) for the OS (system partition or is this configuration now obsolete?

Thanks

[Marco Hogeveen]

Allison,

The most common configuration I see is the one you're having: A RAID1 for the OS and a RAID5 for data and applications.
This is definitely NOT obsolete.
By doing this, you're application and OS don't interfere with each other.

Marco.

[Vincent Farrugia]

Hello,

System performance... yes, 1 single RAID 5 is slower than a RAID 1 pair for the OS and a RAID 5 quartet for the other data.

With hardware RAID you should see a performance improvement over software RAID as well.

As I told you in the other thread, you can do anything you like (well, almost) bearing in mind the properties of all RAID configurations (explained in the other thread).

HTH,
Vince

[Dan Moesch]

You always want to keep an OS on a RAID-1 if possible.

OS performance is always poor on a RAID 5 set due to the amount of write statements an OS makes.

RAID-5 is great for file reads, which makes it good for file services.

Hope that helps!

[Aaron McCavitt]

so you could have, say 5 disks, and have 2 volumes on the first disk, mirror the OS to the two volumes, then put the data on the other 4 and do a RAID 5.

[Dan Moesch]

You wouldn't want to do that at all, then you would have no disk fault tolerance at all.
If you have 5 disks, use 2 for an RAID 1 (OS) and 3 for a RAID 5 (Data).

BTW - You need 2 disks to have a RAID 1, you can't do a RAID 1 with one disk.

[Aaron McCavitt]

so what would be the best way to set that up,,,at a hardware level or a software level? and if it is hardware or software...can you explain the way you would do it? like using Netraid utils or the navigator CD

[Dan Moesch]

Aaron,

You always want a hardware level RAID, software level RAID usually chokes the OS.

To do hardware level raid, you need a RAID card, if its an HP RAID card, you can hit crtl-m during the server boot sequence (it prompts you anyways) if the RAID card is and HP "si" series (3si etc).
If its an HP "M" series card, you can hit ctr-a during the server boot sequence (it prompts you anyways)

Any HP RAID card can be configured via the navigator cd........

If you need more details than that, you may want to do some homework.