Thread (23 messages) 23 messages, 4 authors, 2014-02-05

Re: Very long raid5 init/rebuild times

From: Marc MERLIN <hidden>
Date: 2014-01-29 01:01:59

On Tue, Jan 28, 2014 at 06:56:32PM -0600, Stan Hoeppner wrote:
On 1/28/2014 10:50 AM, Marc MERLIN wrote:
quoted
On Tue, Jan 28, 2014 at 01:46:28AM -0600, Stan Hoeppner wrote:
quoted
quoted
Today, I don't use PMPs anymore, except for some enclosures where it's easy
to just have one cable and where what you describe would need 5 sata cables
to the enclosure, would it not?
No.  For external JBOD storage you go with an SAS expander unit instead
of a PMP.  You have a single SFF 8088 cable to the host which carries 4
SAS/SATA channels, up to 2.4 GB/s with 6G interfaces.
 
Yeah, I know about those, but I have 5 drives in my enclosures, so that's
one short :)
I think you misunderstood.  I was referring to a JBOD chassis with SAS
expander, up to 32 drives, typically 12-24 drives with two host or two
daisy chain ports.  Maybe an example would help here.

http://www.newegg.com/Product/Product.aspx?Item=N82E16816133047
Ah, yes, that.
So indeed in the price category of a PMP chassis with 5 drives ($150-ish), I
haven't found anything that isn't PMP or 5 sata cables.
Yeah, something definitely not right.  Your RAID throughput is less than
a single 7.2K SATA drive.  It's probably just something funky with that
JBOD chassis.
That's also possible.
If/when I have time, I'll unplug things and plug the drives directly to the
card as well as try another MB.

Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/  
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