5TB raid

[Madison Kelly]

teddy wrote:
> Need to make a 5TB raid.
> I could go with a canned solution. But that would be no fun.
> 
> I was thinking about
> 
> One HighPoint RocketRAID 2322 PCI Express SATA II card (2 SAS connectors)
> Two 4 bay SATA2 enclosures with hotswap drive.
> EIGHT WD Caviar 1TB (Green) SATA drives not listed (Hitachi and Sumsung 
> listed)
> 
> Setup the hw raid
> Fill both 4 bay enclosures with four 1TB drives
> Install Gentoo OS with RAID1 with two 80GB IDEs (basic OS only,/home 
> /var etc. but NO DATA!)
> (make a third copy if they request...raids do not prevent operator errors)
> use IDEs as /dev/hda so the sata enclosures start with /dev/sda

Be aware that more and more distros are running ATA through the SCSI 
layer. My humble laptop running the recent Ubuntu shows my IDE drive as 
'/dev/sda'. Just an FYI.

> After OS install is complete then attach the sata enclosures
> and setup each as a RAID5 using mdadm, fstab at bootup
> 
> /dev/sda1 sda2 sda3  sda4=standby
> /dev/sdb1 sdb2 sdb3 sdb4=standby
> 
> (you could probably get away with using seven 1TB drives, as long as you 
> have email notification on a failed drive an replaced it immedialtely 
> with the 7th drive)

If you are concerned about suffering a 2-disk failure, look at RAID-6. 
It's simply RAID-5 with a second parity bit. Do be careful though; in a 
failed state you will suffer performance degradation if your controller 
doesn't support hardware XOR (and sufficient memory). This is true with 
any parity-based RAID level.

> /raid1=3TB RAID5 on enclosure1, mount as ext3 /raid1 via rc.local
> /raid2=3TB RAID5 on enclosure2, mount as ext3 /raid2 via rc.local
> 
> Call HighPoint for advice first.

Why not create one large RAID array? Many applications, like many SQL 
DB's, suffer performance hits on RAID /until/ you get to 6+ drives in a 
single array.

Madi
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