Re: How many of you use S.A.M.E?
- From: "Alex Gorbachev" <gorbyx@xxxxxxxxx>
- To: ax.mount@xxxxxxxxx
- Date: Thu, 1 Feb 2007 21:30:35 -0500
Sorry. This performance really sux even for 256K disks.
I would check if you are by any chance using the fist and the last
slices on the disk most extensively or perhaps mirror on two slices of
the same disk or something crazy like that. It might sound completely
stupid but you never know how far storage admin can go in a hurry
especially with such an abstraction - having bunch of 8G slices (do
they call them hypers?).
Someone mentioned you should have 100 IOPS per spindle assuming IO is
pretty much random. I have similar figure from my experience for 10K
disks and IO would be on the level of 10ms easily with Symetrix
providing there are no other bottlenecks.
On 2/1/07, amonte <ax.mount@xxxxxxxxx> wrote:
Hi
Anyone here use Stripe.All.Mirror.Everything methology? The one claimed by
Mr Loaiza 6 years ago?
Not long ago I posted to list several I/O problems I have with Storage. I
was told yesterday that the EMC we have is using Meta Devices, some sort of
SAME. I was told by the EMC guy that the SAN has 120 disks with RAID 1+0,
256GB disks. In the factory it is configured with a internal stripe, 256GB
disk is divided into slices of 8GB. So we have 120 disks each disk with 32
slices.
With that configuration you take slices from several physical disks to form
LUNs. He syas that this is what they call Mete Devices and usually they do
that only when the customer is in a hurry and needs the disks badly and dont
have time to make a better planning. He further said that this sort of
configuration he has seen response times of over 120ms and it is not
unusual. The porblem with our disks is that sometimes we get like 80ms
responsetime and most of time beteen 25 and 60.
I wonder, is Mete Device a SAME configuration? Sure it is deadly easy to
configure and maintain but then we are suffering performance problems. The
EMC box is used by over 10 databases, from OLTP to DWH and some of them
Hybrid configuration. So the chance that a disk is used by all 10 databases
is quite easy. Wont the disk head go crazy when 10 databases is asking for
data in several sectors in the same disk? May the chance of that is quite
small however I would not be surprised that a disk is being used by 3, 4
databases concurrently.
TIA
Alex
--
Best regards,
Alex Gorbachev
The Pythian Group
Sr. Oracle DBA
http://www.pythian.com/blogs/author/alex/
http://blog.oracloid.com
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