Aye... in theory, a single hard disk could max out a GigE connection. In practice, for a server with multiple clients, no such luck.
From: Serge Dumoulin serge@ordigraphe.com
Subject: Re: Question about network deleting.
To: discuss@studiosysadmins.com
Received: Wednesday, September 2, 2009, 7:59 AM
These numbers are for sequentials
read write. Unfortunatly? random requests? and
fragmentation will make the numbers really lower? and
this is where number of spindle might really help.
serge
On 2-Sep-09, at 10:48 AM, Burns Tom wrote:
If you put 5 Seagate ST31500341AS drives, (which will max
out @ 120
MB/sec) on a port-multiplier backplane, won't that
oversubscribe the
SATA II port connected to the backplane?
Lessee...? Sata II provides 3 Gbits/sec = 3000
Mbits/sec
divide by 8 for Bytes = 375 MBytes/sec
5 drives maxed out (120 MBytes/sec * 5) = 600 MBytes/sec
So for max port multiplier utilization you would only want
3 drives per
SATA II port, for a max of 360 MB/sec, which will fit under
your 375
MB/s SATA II port throughput.
Does a 1.5 TB Seagate AS series drive really deliver
120MB/sec
sustained?
Maybe you could get away with 4 drives per port-multiplier
backplane,
but 5?
I suppose if you paid attention to which spindles were
attached to which
RAID you could make sure that all 5 drives per backplane
weren't reading
or writing at the same time.
Wouldn't LVM have more flexibility in this regard than
mdadm?
.../Tom
-----Original Message-----
From: studiosysadmins-discuss-bounces@studiosysadmins.com
[mailto:studiosysadmins-discuss-bounces@studiosysadmins.com]
On Behalf
Of Andrew Klaassen
Sent: Wednesday, September 02, 2009 10:19 AM
To: discuss@studiosysadmins.com
Subject: Re: Question about network deleting.
--- On Tue, 9/1/09, Klaus Steden klaus-s@moving-picture.com
wrote:
You could try one of these ...
http://blog.backblaze.com/2009/09/01/petabytes-on-a-budget-how-to-build-
cheap-cloud-storage/
I've been thinking about building something like that, but
I've had a
hard time finding good info about port-multiplier
backplanes.? The good
news is that Backblaze seems to have a working, well-tested
config using
port multipliers; the bad news is that they thank "James
Lee at Chyang
Fun Industries in Taiwan for customizing SATA boards to
simplify our
design".? I probably don't have the buying power clout
to get James Lee
- as nice a guy as he might be - to do that for me.?
(Although... if
they have a few extras left over from the Backblaze
build...)
Andrew
?
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