On 11-Jan-10, at 1:12 PM, Bob Friesenhahn wrote:
On Mon, 11 Jan 2010, Anil wrote:
What is the recommended way to make use of a Hardware RAID
controller/HBA along with ZFS?
...
Many people will recommend against using RAID5 in "hardware" since
then zfs is not as capable of repairing errors, and because most
RAID5 controller cards use a particular format on the drives so
that the drives become tied to the controller brand/model and it is
not possible to move the pool to a different system without using
an identical controller. If the controller fails and is no longer
available for purchase, or the controller is found to have a design
defect, then the pool may be toast.
+1 These drawbacks of proprietary RAID are frequently overlooked.
Marty Scholes had a neat summary in a posting here, 21 October 2009:
http://www.mail-archive.com/zfs-discuss@opensolaris.org/msg30452.html
Back when I did storage admin for a smaller company where
availability was hyper-critical (but we couldn't afford EMC/
Veritas), we had a hardware RAID5 array. After a few years of
service, we ran into some problems:
* Need to restripe the array? Screwed.
* Need to replace the array because current one is EOL? Screwed.
* Array controller barfed for whatever reason? Screwed.
* Need to flash the controller with latest firmware? Screwed.
* Need to replace a component on the array, e.g. NIC, controller or
power supply? Screwed.
* Need to relocate the array? Screwed.
If we could stomach downtime or short-lived storage solutions, none
of this would have mattered.
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