Setting up Raid on a Dell PowerEdge 2850

You can 1 raid 1 For OS with 2 Disk 73 GB, another Raid 1 with 2 Disks 146Gb and 1 Raid 5 with the four 320 Dsiks. Raid 1 is mirroring, you can make radi 5 with minimum 3 disks and then you loose only 1 disk .

Setting up a RAID 1 for OS and RAID 5 for data is quite typical and good way to go about it.  I would use the 2 x 73GB for your OS and the 146GB's for data.

However A RAID 5 array requires a minimum of 3 disks.  To achieve a RAID 1 and RAID 5 you are 1 disk short.

What is the SCSI controller card/chipset in the 2950, is it a RAID controller or just a standard SCSI interface?  The server will not necessarily not have RAID support.  In which case you would have to acquire a card for RAID support or install the OS onto one drive and create a software RAID from the OS.

You will need to decide on what kind of array you want with the 4 Disks if you can't fit another drive, you will need to check to see if your server can create and support the raid or settle for a software raid, and then you can move forward with this.

Hi Thanks for the reply
A few things...
Can i set up more than one raid 1?
e.g raid 1 on the two 73gb discs and another raid 1 array on the two 146gb discs? or can i use the 4 discs to create a raid 5 and then partion the disc for the server 2003 o/s?
also
How can i tell which discs are which during the set up process?
thanks again

sorry i replied a bit quick and didnt see your post rob, let me digest it and il reply.. thanks

Hi,
i believe the scsi controller is a adaptec 29160 but i also see, during POST, reference to a PERC (poweredge raid controller) and also a Logic Configuration Utility...
Nathan

Ok, going straight to the Adaptec product page, the 29160 is not a RAID card, simply an interface card that lets you have SCSI devices.  

To achieve a RAID with that card you will have to install the OS to one of the disks and then create your raid from disk management in the server OS.  It's always preferable to use a hardware RAID rather than software raid but it will work.

The PERC Card will be probably a separate card and most likely a SATA Card.

Regards the use of disks/partitions, yes you can have multiple RAID 1 Arrays.

You could install the OS to one of the smaller drives, create the RAID 1 with the other disk.  Then create a second RAID 1 with the remaining 2 disks.

If you choose to create a RAID 5 array you will end up not using disk space as you have a mix of capacities an it doesn't help that you are now restricted to a software raid.

I would install the OS to 1 73GB drive and create your 2 x RAID 1 arrays.  OS and Data.

Just to help Robert above explain, if you attempted to Raid 5 with the 4 drives, you would limit the 146gig disks to 73gigs because the 73gig are the most limiting factor. You would have 4x73gig drives effectively and lose one to the raid process (3 x73gig combined to 1 logical drive. Without the addition of another 146gig (good luck finding one), you will not have the more ideal configuration..OS on the 'stiped' Raid1 2x73gig drives, and Data on the Raid 5 (3x146gig - for 1... 292gig logical drive). You lose 1/n drive space in Raid 5, where n=number of drives in the array.

So to reiterate what Robert said...."you can have multiple Raid 1 arrays" with your current hardware. Hardware raid is always better than software.

Hi,
Thanks for all the contributions so far.
Ok, i understand the limitations of raid 5 in my case and i also understand what robert says regarding 2 x raid .
Howeverwhen in POST i see the following
'Poweredge expandable raid controller bios'
select <Ctrl m> to run configuration utility, when i enter into this utility the screen has a heading
'Perc/cerc bios configuration utility'
down the left column there are headings such as
Configure, initialize, objects, clear
when i go into configure i see a sub menu of
Configure – easy configuration –
this comes up with a screen headed 'array selection menu'
there are then 2 colums raid ch-0 and raid ch-1 and what looks like my 4 hdd drives
please excuse my ignorance but cant i set raid up in there?

What PERC card is it?  If the drives are connected to this card and are showing up, then yes I presume you can RAID them if you have the option to do so.  

Which would mean they are not plugged into the adaptec.   Which is great as a hardware RAID is far more preferable.

Just remember to press F8 when you boot the server OS install when prompted and have your 2003 drivers on the root of a floppy disk ready.

im really sorry but i have no idea how to find out what perc card it is.
would you know how to find out?
cheers again

You will need to know to acquire the drivers.  It should say somewhere within the controller menu/bios.  

But it shouldn't be a problem, looking at the Dell Driver website, there is only 1 driver for SCSI-RAID controllers covering all the possible cards.  As long as the server was bought with the card rather than added in, the below driver should be correct.

http://support.dell.com/support/downloads/driverslist.aspx?os=WNET&catid=35&dateid=-1&impid=-1&osl=EN&typeid=-1&formatid=-1&servicetag=&SystemID=PWE_PNT_P3C_2850&hidos=WNET&hidlang=en&TabIndex=&scanSupported=False&scanConsent=False

Go ahead and raid it and see how you get on.

appreciate your help. i will get back to you.
thanks robert

I've worked on Dell PowerEdge Servers since 1995 and can say that PowerEdgeTech's (above) is spot on--do what he says and you will be OK!

Hi @ PowerEdgeTech - apologies for reply being late ive only a few hours a day to play around with this so please forgive me.
ive followed your instructions to the letter - ive gone into the ctrl m and got this far - taken from your last post..

Configure, Clear Configuration, View/Add (your drives will show as Ready), press the Space Bar on each of the 73GB drives (they will start blinking), then Enter (they will stop blinking), then F10 to Configure, press the Space Bar to select the "span" listed, then F10, select RAID 1 and leave all other settings along (unless you know exactly what you are doing), then Accept.  
This is where i get stuck - it wont let me accept the span. it just says no and i cant change it..

any ideas?
thanks

When it shows you the span, the only option you have is to select it (Space Bar on it - its text should change color after doing so) then continue to the next screen by hitting F10 (to configure).

Hi
Thanks for the reply.
i dont know what happened there ( i must have been doing something wrong) its worked now and asked me to save the configuration (which ive done).
ive now gone into initialize - it gives me a msgbox of 'this logical drive is in background initialization state - it cannot be selected for desired operation' by hitting f6 i see a progress bar
is this normal?
ps thanks already for all your help

Background init's can be automatic, so if you can't select the logical dirve for initialization, then that's ok.  The background init will take several hours to complete, so you probably don't want to watch it, but you also don't have to wait for it to complete to begin your install.

ok il let it run i think.
Anyway il close this question now awarding you the points, if i have any problem installing the o/s il repost.
Thanks for all your help and expertise...

No problem.  Good luck.