I also had a 760 survive doing 17,000 nfs ops/second once. ...
When running compiles, it is not unusual for us to see numbers over 22,000 on the op-panel of our 760. Anyone know where the top end of an 840 is? Support has been unable to answer that one for us.
So in our move to an 840 I want to configure it's volume for maximum performance. The ground rules are two FC-AL adapters, seven full trays of 18G drives. All one volume is very desirable.
Now the SPECsfs97 benchmark on the 840 states:
* The F1 filesystem was composed of two RAID groups, each containing 17 data disks and one parity disk. Two spare disks were present
* The F1 filesystem was striped across both disk controllers
Since I have to assume that NetApp would use a high performance architecture for the benchmark I am guessing that this is the way to go, but there is quite a bit of detail missing.
Is it a good or bad idea to split a raid group over two FC-AL interfaces?
What does "striped across both disk controllers" mean?
If there are spare disks (same size) on both FC-AL interfaces and a disk fails Which one is used to rebuild? (Same FC-AL or random choice)
Is it a good or bad idea to split a volume over multiple FC-AL interfaces?
The need for speed
Graydon Dodson (606) 232-6483 grdodson@lexmark.com Lexmark International Inc.
Graydon Dodson wrote:
Is it a good or bad idea to split a raid group over two FC-AL interfaces?
What does "striped across both disk controllers" mean?
You almost answered your question with your own question?
If you have two FCAL interfaces, you have two controllers. The filesystem disks(data disks) are spread across both loops, or "striped across both disk controllers".
--tmac
If there are spare disks (same size) on both FC-AL interfaces and a disk fails Which one is used to rebuild? (Same FC-AL or random choice)
Is it a good or bad idea to split a volume over multiple FC-AL interfaces?
The need for speed
Graydon Dodson (606) 232-6483 grdodson@lexmark.com Lexmark International Inc.
-- ******All New Numbers!!!****** ************* *************
Timothy A. McCarthy --> System Engineer, Eastern Region Network Appliance http://www.netapp.com 240-268-2034 Office \ / Page Me at: 240-268-2001 Fax / 888-971-4468
Since I have to assume that NetApp would use a high performance
architecture
for the benchmark I am guessing that this is the way to go, but there is
quite
a bit of detail missing.
Is it a good or bad idea to split a raid group over two FC-AL
interfaces?
Somewhat bad... as has been talked about here before, there is a small write penalty introduced, on the order of 10%, which only introduces itself noticeably under heavy write loads. However, you should avoid it if you can.
What does "striped across both disk controllers" mean?
It means the filesystem was striped across both disk controllers. I does not say any raid group was striped across disk controllers. I suspect that they had all one filesystem, two raid groups, one raid group per each controller.
If there are spare disks (same size) on both FC-AL interfaces and a disk
fails
Which one is used to rebuild? (Same FC-AL or random choice)
That I don't know. I think someone brought this up here before.
Is it a good or bad idea to split a volume over multiple FC-AL
interfaces?
Neither. I guess, in some sense, it's slightly bad, since if you lose a particular controller you would only lose volumes on that controller, but my guess is in such event you are looking at a reboot or a failover situation anyway.
Bruce
Bruce Sterling Woodcock wrote:
Since I have to assume that NetApp would use a high performance
architecture
for the benchmark I am guessing that this is the way to go, but there is
quite
a bit of detail missing.
Is it a good or bad idea to split a raid group over two FC-AL
interfaces?
Somewhat bad... as has been talked about here before, there is a small write penalty introduced, on the order of 10%, which only introduces itself noticeably under heavy write loads. However, you should avoid it if you can.
Remember this is an F840. I beleive the issue was specific to the F700 series. The F840 does not have the same issue, plus it has 3 primary PCI buses to spread loads across.
-- ******All New Numbers!!!****** ************* *************
Timothy A. McCarthy --> System Engineer, Eastern Region Network Appliance http://www.netapp.com 240-268-2034 Office \ / Page Me at: 240-268-2001 Fax / 888-971-4468
Remember this is an F840. I beleive the issue was specific to the F700
series.
The F840 does not have the same issue, plus it has 3 primary PCI buses to spread loads across.
To quote Johnny Carson, "I did not know that."
With 3 buses then there should be no problem; I assume each controller is on its own bus.
Bruce
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Bruce Sterling Woodcock -
Graydon Dodson -
Timothy A. McCarthy