Need help in building RAID from 4 HDDs

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kamran

Geek Trainee
Hello everyone,

I have just recently purchased a storage / application server with 4x500GB SATA HDDs for my office and would like to know how to build a reliable RAID enabled storage solution. Machine specs are:

- Intel Pentium 4 3.2 GHz
- 1.0 GB DDR2 RAM
- Intel 955X chipset based motherboard
- 1 x 80GB SATA HDD + 4 x 500 GB SATA HDD (2 TB)
- 2 x 4-port PCI SATA RAID card (based on Sil32 controller)
- AOpen server chasis
- 700W PSU

I would be using the single 80GB HDD to install the OS. I want to use all 4x500GB HDDs in RAID mode. I won't be using the onboard Intel RAID facility as I've purchased 2 PCI cards for this (1 for connecting the 4 HDDs and 2nd for connecting 4 more HDDs in future). From what I know, RAID5 is the most recommended RAID mode I sould go for as it provides good data redundancy.

I would like some guidelines as to how to create this RAID5 array. As I know, it's done by accessing the RAID controller's menu that appears just before Windows starts loading. Some of my questions are:

1. RAID5 requires space for parity information. How much space is needed for this? For example, how much of the 2TB would be available for storing data? (I do know that this information is used for rebuilding the array in case if any one of the disks fail).

2. After creating the array, how would it appear to Windows? A single drive or 4 HDDs?

3. If all of the 2 TB becomes occupied, can I swap in a larger HDD with the smaller one?

4. If the RAID controller dies, how would I access my data on the 4 HDDs? Could I connect them individually to a PC to make backups? Could I connect them to a RAID controller card based on a DIFFERENT chipset and still access my data? Or the RAID controller card must be based on the same chipset on which the RAID array was created?

Any information in this regard would be very welcome! Thanks.

Regards,
Kamran
 
RAID 5 is a complicated setup and if one drive fails, it would be a bit difficult to replace. saying that, it would be better if you would just use the RAID 1 setup, it's far easier to setup, fix and recover the data.
kamran said:
1. RAID5 requires space for parity information. How much space is needed for this? For example, how much of the 2TB would be available for storing data? (I do know that this information is used for rebuilding the array in case if any one of the disks fail).
Click to expand...

the redundancy uses the parity section of the drives, so it effectively uses half the space for backup.

2. After creating the array, how would it appear to Windows? A single drive or 4 HDDs?
Click to expand...

not sure about this one, but i think it would show as four or two

3. If all of the 2 TB becomes occupied, can I swap in a larger HDD with the smaller one?
Click to expand...

if u want to replace the two tb, then yes, it would be possible, u just have to reset it up again.

4. If the RAID controller dies, how would I access my data on the 4 HDDs? Could I connect them individually to a PC to make backups? Could I connect them to a RAID controller card based on a DIFFERENT chipset and still access my data? Or the RAID controller card must be based on the same chipset on which the RAID array was created?
Click to expand...
yes you can connect them individually. and yes you can use a different card on a different chipset and still access your data.


hope this helps
 
Yes, if you created it under the RAID BIOS.

If you're using a RAID array, you need to understand that the output is based on the smallest drive size in the array. RAID 5 won't give you a full 2TB, due to the parity that's in use. You're looking at 1.5TB as it will take up RAID 0 would give you the full 2TB, but then you sacrifice the Redundancy part of RAID.

You simply cannot replace one drive in the array with another sized drive. You would either need to go to JBOD (Just a Bunch Of Disks), or upgrade all the drives in the array to a larger size and then move the image of that array over to the new array. This isn't to say you can't put a 750GB drive if a 500GB dies, but you'll not see 250GB of it in use, due to the design of RAID being based off the smallest disk in the array.

Also, I don't know if all 955X motherboards featured RAID 5 support, so before you go to set that up, you might want to find that info out.
 
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