Look at the attached email message. There was a thread of discussion about
this a month ago.
Anyway I am going to test it on a small scale in one of my projects.
I was told that 1MB (one track) stripe size is the smallest efficient size
we should have b/c EMC will read 1MB anyway (one track) even if you need
less.
Regards,
Waleed
Any views or opinions presented in this email are solely those of the
author and do not necessarily represent those of the company
-----Original Message-----
Sent: Wednesday, April 24, 2002 3:20 PM
To: Multiple recipients of list ORACLE-L
Waleed,
That's interesting. I just looked at the emc site and
still do not see anything that would lead me to
believe that they support hardware striping except for
the IBM Sequential Data Striping.
This was for the Symetrix 3000, 5000 & 8000 line.
I would be keenly interested to know as we have many
TB here of EMC and all of it is software striped.
What product line are you referring to? When did they
start?
Thanks,
Bill
--- "Khedr, Waleed" <[EMAIL PROTECTED]> wrote:
> Now they have hardware striping.
>
> Regards,
>
> Waleed
>
> -----Original Message-----
> Sent: Wednesday, April 24, 2002 2:29 PM
> To: Multiple recipients of list ORACLE-L
>
>
> My understanding was that EMC does not stripe its
> disks. they just have mirror and RAID S.
>
>
> --- Sr DBA <[EMAIL PROTECTED]> wrote:
> > Why would you software stripe it if you are using
> > EMC?
> > ----- Original Message -----
> > From: "Johnson Poovathummoottil"
> <[EMAIL PROTECTED]>
> > To: "LazyDBA.com Discussion"
> <[EMAIL PROTECTED]>
> > Sent: Wednesday, April 24, 2002 8:57 AM
> > Subject: Number of File systems to use.
> >
> >
> > > All,
> > >
> > > Although this has been discussed many times. My
> > boss
> > > wants other opinions on this.
> > >
> > > We EMC storage whcih uses 9 gig disks.
> > > We also use veritas volume manager.
> > >
> > > We plan to upgrade our SUN ultra e6500 to sun
> fire
> > 15K
> > > machine. During to move we want to do a little
> > reorg.
> > > This machine will have 6 partitions, 3 for the
> > OLTP
> > > databases and 3 for the warehouse.
> > >
> > > The warehouse currently uses 20 file systems 25
> GB
> > > each(3 disks raid S) for data and index. We have
> > > agreed on making the file systems to use 4 disks
> > and
> > > stripe it with 256 KB stripe size. There are two
> > > opinions regarding the number of file systems.
> > >
> > > 1: 50 file systems of 15 GB each. In this case
> the
> > 4
> > > disks are not fully used. What is ramainig after
> > the
> > > 15 GB can be alloted to other file systems other
> > than
> > > the ones used by the database. Advantage IO
> spread
> > > over disks.
> > >
> > > 2: 20 file systems of 34 GB each. All four disks
> > are
> > > fully used. IO over 80 disks.
> > >
> > > Question.:
> > > 1:Since we are using EMC do we need to pay so
> much
> > > attention to spreading IO.
> > > 2: Any problems/advantages in having too many
> file
> > > systems.
> > >
> > > Please give all your opinions.
> > >
> > >
> > >
> > >
> __________________________________________________
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> > more
> > > http://games.yahoo.com/
> > >
> > > --------
> > > Oracle documentation is here:
> >
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>
>
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--- Begin Message ---
Take a look at this pdf file and search for 'microcode 5265' :
http://powerlink.emc.com/MediumFreq/21108_Symmetrix_3832_Installation_Manual
.pdf?_requestid=260
Regards,
Waleed
Any views or opinions presented in this email are solely those of the
author and do not necessarily represent those of the company
-----Original Message-----
Sent: Tuesday, April 02, 2002 12:38 PM
To: Multiple recipients of list ORACLE-L
Waleed & list,
To define the terms we have on hand:-
A contiguous meta volume requires the hyper volumes to
be sequential. A non-contiguous does not require the
hyper volumes to be sequential.
I want to reiterate again that the concept of "pure
striping" at the hardware level, is still not there in
EMC, even though you have documentation that claims
that you do. Let me explain.
When you look at "pure striping", there are 2 aspects
to it :-
1) The read aspect
2) The write aspect
Take an example of a 4-way striped volume. The read
aspect provides us the capability for all 4 drives to
independently spin and service I/O from each of the
drives. This the EMC device does, after the data has
been placed on all hypers that support a meta volume.
The write aspect needs to offer the same
functionality. So, if you are writing to 4 distinct
blocks (each on 1 disk), then each drive should be
able to write 1 block in an independent fashion.
That is where, the EMC hardware striping is not
complete. This is because, the 4 blocks that need to
be written to the "meta volume" with 4 hypers
(regardless of whether it is contiguous or not), will
happen in "sequential" fashion. Meaning, to write 4
blocks into the "striped volume", the first block will
be written to the first hyper, followed by the second
block to the second hyper and so on. As you can see
the blocks that need to be written are queued up, so
that they are written in a sequential fashion on the
underlying hypers. This can and will cause severe
write-intensive I/O bottlenecks.
Why is this implemented this way? No specific reasons,
except, "that is how it is right now". It has been
rumored that microcode 5x68 or 5x69, will do that.
Remains to be seen.
So all the EMC "striping" does right now is to
alleviate the problem of read-intensive operations not
hammering a single drive, provided the data is spread
across all the underlying hypers. I am not very
familiar with the Engenuity product offering, hence
cannot comment on that, but from what I have heard, it
is a software-based volume management product.
Best regards,
Gaja
--- "Khedr, Waleed" <[EMAIL PROTECTED]> wrote:
>
> It looks like it's available now.
>
> This is from: ResourcePak for Windows Version 3.2
> Product Guide
>
> "Symmetrix Microcode level 5x65 includes support for
> concatenated
> (contiguous) and striped metavolumes.
> Noncontiguous metavolumes (including striped)
> require EMC Enginuity(tm)
> (5x66 microcode) or higher."
>
> Regards,
>
> Waleed
> -----Original Message-----
> To: Multiple recipients of list ORACLE-L
> Sent: 4/1/02 5:38 PM
>
> Waleed & list,
>
> I researched this issue recently and found out that
> the meta volume was "concatenating a bunch of hyper
> volume". As you know, concatenation is NOT striping.
> The hyper volumes get filled with data one after
> another, eventually giving you the "simulation of a
> striped volume", when all hypers are filled with
> data.
>
> I don't know about the "single-host vs. multi-host"
> addressibility issue. There are plans for supporting
> "true striped volumes" in microcode level 68 or 69.
> From some "reliable sources" that does not look like
> it will happen any time soon. So until then, you
> should consider created mirrored hyper volumes
> within
> EMC (RAID 1) and then create a striped volume using
> Veritas Volume Manager, giving you a RAID 1+0
> configuration, which is ideal.
>
> Best regards,
>
> Gaja
>
> --- "Khedr, Waleed" <[EMAIL PROTECTED]> wrote:
> > Four years ago the only hardware striping
> available
> > on EMC I was aware of
> > was RAID-S.
> > Recently researching striping ideas on EMC and was
> > told that we can achieve
> > raid0+1 hardware striping on EMC.
> >
> > I was told that EMC has some layer called
> > meta-volume that is made of many
> > other hyper-volumes.
> >
> > Told also that meta-volumes could be raid-0
> > (striped) and it's not a
> > single-host addressable volume.
> >
> > Does anybody know anything about this? Can we
> really
> > get a hardware striped
> > volume using EMC?
> >
> > Any limitations there?
> >
> > Thanks.
> >
> >
> > Waleed
> >
> >
> > Any views or opinions presented in this email are
> > solely those of the
> > author and do not necessarily represent those of
> the
> > company
> >
> > --
=====
Gaja Krishna Vaidyanatha
Director, Storage Management Products,
Quest Software, Inc.
Co-author - Oracle Performance Tuning 101
http://www.osborne.com/database_erp/0072131454/0072131454.shtml
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