OT: Torn between SCSI and SATA for RAID

[Chad Leigh -- Shire.Net LLC]

On May 11, 2006, at 4:51 AM, cknipe at savage.za.org wrote:

> Quoting lars <lars at gmx.at>:
>
>> I recently read an interesting comparison
>> on consumer and enterprise grade harddisks:
>>
> http://www.seagate.com/content/docs/pdf/whitepaper/ 
> D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf
>
>
> This was posted yesterday in responce to my question as well.  That  
> document
> deals mainly with the performance and reliability of the different  
> types of
> hard drives (i.e. SATA vs SCSI).
>
> My questions that I'm posting is not really related towards the  
> performance of
> the system, it's more towards the capacity of the system... I guess  
> it boils
> down to the physical hardware... How does everything connect, how  
> to expand
> systems, and how to run arrays bigger than what one single  
> controller can
> provide...

Look at the Areca SATA controllers.

An 8 port RAID 6 SATA controller using 8 drives, 1 a hot spare, gives  
you about 5 drives worth of RAID 6 (5 + 2 parity = 7 drives, can  
suffer up to 2 simultaneous drive failures) and the Areca seem to be  
well regarded.  I have an 8 port and a 12 port one but not in service  
yet.  Areca has FBSD drivers.

5 drives * 500GB is a about 2.125 "real" TB (given that 500GB drive  
is not really 500 real GB)  (calculation made with simple ratios and  
could be way off).  The 12 port Areca card with 1 hot spare and RAID  
6 would give you 9 * 500GB = about 3.825 real TB

To get the size of array you want you need to go SATA as the SCSI  
drives aren't really big enough to get that big without getting into  
major major money.  Use good, 24/7 rated SATA drives, not cheap  
maxtor or WD (think seagate or hitachi probably).  Buy an extra drive  
to have or lose some capability and set up 2 hot spares.

I am considering a machine with 2 12 port Areca cards set up with 2  
RAID 6 arrays mirrored using ZFS under Solaris 10 as an nfs storage  
server...

Chad


---
Chad Leigh -- Shire.Net LLC
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