On 10/28/2011 02:37 AM, Pak Ogah wrote:
On 10/27/11 23:52, Eric Shubert wrote:
On 10/26/2011 09:07 PM, Pak Ogah wrote:
On 10/27/11 10:24, Casey wrote:
On 10/26/11 7:55 PM, Eric Shubert wrote:
On 10/26/2011 06:44 PM, Casey wrote:
....
Also, what are you using as a
RAID controller? Hardware, Linux, fakeraid?
Linux software raid. No special hardware controller, just straight
through devices.
These 2560's have PERC3/Di controllers - 128MB RAM, and a battery
backup...is a Linux software RAID a better option? Performance?
Reliability?
My 2,000 Rupiahs, :D
Hardware Raid controller with amount of memory and Backup batery is much
more better than Software.
I only use software raid, if I don't have the controller and want data
redundancy.
I disagree.
Let me begin by saying that if you run raid-5, you'll likely need a
hardware raid solution (not fake raid) in order to handle the cpu
requirements. Raid-5 also can give improved read performance with
many,many drives. That's not a typical scenario though.
With raid-1 or raid-10, there's not enough of a processing requirement
to warrant extra hardware. The main CPU can handle it just fine, and
the hardware raid won't buy you much (freeing up cpu cycles).
With a QMT host, disk performance is probably not going to be your
limiting factor, so I wouldn't be very concerned about performance of
one configuration vs another, so long as you don't need to use raid-5
for whatever reason. If you decide that you must use raid-5, use a
hardware controller for it. I must say though, that I (strongly)
recommend avoiding raid-5 whenever possible.
The big problem I have with hardware raid controllers is that they use
proprietary methods to store the data on disk. When a raid controller
goes bad (and they do), you *must* have an equivalent controller in
order to access the raid array. That's a position I like to avoid
being in. If it's a card that's no longer available, you better have a
couple (that you know work) sitting on the shelf just in case.
On the other hand, with software raid, I can access and recover data
from the drives quite easily with any ol' commodity hardware.
BL, hardware raid controllers are only beneficial with raid-5, which I
don't use or recommend. Give me software raid any (and every) day.
thank you for the insight Eric,
the reason why I am suggesting Hardware raid are (based on my experience):
- I got branded server (HP) from company, and by default the vendor
always ship it with raid controller (P212/P400)
- since the servers got 3 years warranty, and my company and vendor
already have long business relation, so I do not have to worry, if
existing controller broken, I am sure the vendor will help me (so I
don't have to spare a controller on my shelf)
- raid controller is make me easy changing harddrive (hot-swap)
- after 10 years, only 1 of 20 servers that have broken the controller,
and that is and old server (bought at 2002), we replace it already.
- hardware raid controller is supported by vmware vsphere/hypervisor
- once I had problem converting a linux with software raid 1 into vm
using vmware vconverter, so I have to reinstall the OS/apps again :(
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Sounds like you've chosen the best option for your situation. I've had
good experiences historically with HP, and I expect that will continue
(for others) given HP's recent change of focus (they're getting out of
the consumer market, and focusing on datacenter type customers). That
sort of vendor support comes with a price tag though, which some people
cannot afford or choose not to spend. Which says nothing about vendor
lock-in. IIRC, those servers require 'special' drives from HP as well. I
prefer generic 'commodity' hardware. I think it maintains better
competition between vendors, and carries a much smaller price tag.
BTW, I'm not surprised that vmware vconverter had a problem with raid. I
would expect to have to do some manual 'magic' to make that happen.
Thanks for your insight.
--
-Eric 'shubes'
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