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Subject: RE: do we support volumes with multiple raid levels luns?
Date: Fri, 22 Feb 2008 10:31:26 -0800
Message-ID: <BB375AF679D4A34E9CA8DFA650E2B04E0875EF70@onstor-exch02.onstor.net>
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Thread-Topic: do we support volumes with multiple raid levels luns?
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References: <BB375AF679D4A34E9CA8DFA650E2B04E05C742F7@onstor-exch02.onstor.net> <BB375AF679D4A34E9CA8DFA650E2B04E0346AFCC@onstor-exch02.onstor.net>
From: "Eric Barrett" <eric.barrett@onstor.com>
To: "John Rogers" <john.rogers@onstor.com>,
	"Sandrine Boulanger" <sandrine.boulanger@onstor.com>,
	"Dave Limato" <dave.limato@onstor.com>,
	"dl-Design Review" <dl-designreview@onstor.com>,
	"dl-Marketing" <dl-marketing@onstor.com>

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As a side note, that's not a great idea in practice, because...

1) If you want to throw away 3-4 high-speed disks for a single volume,
well, OK, then it will help.  But you're throwing away hundreds of GB of
storage for a fairly unimpressive speed gain.
2) If you don't, you're probably going to want to use it for other
volumes.  And if you do that, then the 3-4 disks shared by the other
volumes' journals go from an advantage to a bottleneck very quickly.


> _____________________________________________=20
> From: 	John Rogers =20
> Sent:	Friday, February 22, 2008 10:26 AM
> To:	Sandrine Boulanger; Eric Barrett; Dave Limato; dl-Design Review;
> dl-Marketing
> Subject:	RE: do we support volumes with multiple raid levels
> luns?
>=20
> Isnt that the idea with the raid10 logging lun with raid 5 luns
> filling in the rest of the volume. I think we have tried this in
> performance testing.
>=20
> _____________________________________________
> From: Sandrine Boulanger=20
> Sent: Friday, February 22, 2008 10:25 AM
> To: Eric Barrett; Dave Limato; dl-Design Review; dl-Marketing
> Subject: RE: do we support volumes with multiple raid levels luns?
>=20
> That's not my point, I know the labels are meaningless; I just want to
> know if we would support customers who mix physical raid levels in the
> same volume.
>=20
> _____________________________________________
> From: Eric Barrett=20
> Sent: Friday, February 22, 2008 10:07 AM
> To: Sandrine Boulanger; Dave Limato; dl-Design Review; dl-Marketing
> Subject: RE: do we support volumes with multiple raid levels luns?
>=20
> We should not prevent it, since the labels are meaningless.  If they
> had some actual weight in that they always accurately reflected the
> RAID type as given by the array, it would make sense to do so.
>=20
>=20
> _____________________________________________=20
> From: 	Sandrine Boulanger =20
> Sent:	Friday, February 22, 2008 9:39 AM
> To:	Dave Limato; dl-Design Review; dl-Marketing
> Subject:	RE: do we support volumes with multiple raid levels
> luns?
>=20
> I know there are ways to do it, but should we prevent it or not. I
> want an official answer.
>=20
> _____________________________________________
> From: Dave Limato=20
> Sent: Friday, February 22, 2008 9:25 AM
> To: Sandrine Boulanger; dl-Design Review; dl-Marketing
> Subject: RE: do we support volumes with multiple raid levels luns?
>=20
> Why yes Sandrine, I believe we do, but I think it is somewhat
> difficult to support because of the artificial raid levels.
>=20
>=20
> _____________________________________________
> From: Sandrine Boulanger=20
> Sent: Tuesday, February 19, 2008 8:20 PM
> To: dl-Design Review; dl-Marketing
> Subject: do we support volumes with multiple raid levels luns?
>=20
> Our lun labeling has a string for raid level as a parameter. Even we
> can artificially label luns as Raid-5 even if the physical read level
> on disk id Raid-0, do we support mixing physical raid levels within
> the same volume?=20

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<P><FONT SIZE=3D2 FACE=3D"Arial">As a side note, that's not a great idea =
in practice, because...</FONT>
</P>

<P><FONT SIZE=3D2 FACE=3D"Arial">1) If you want to throw away 3-4 =
high-speed disks for a single volume, well, OK, then it will help.&nbsp; =
But you're throwing away hundreds of GB of storage for a fairly =
unimpressive speed gain.</FONT></P>

<P><FONT SIZE=3D2 FACE=3D"Arial">2) If you don't, you're probably going =
to want to use it for other volumes.&nbsp; And if you do that, then the =
3-4 disks shared by the other volumes' journals go from an advantage to =
a bottleneck very quickly.</FONT></P>
<BR>

<P><FONT SIZE=3D1 =
FACE=3D"Tahoma">_____________________________________________ </FONT>

<BR><B><FONT SIZE=3D1 FACE=3D"Tahoma">From: &nbsp;</FONT></B> <FONT =
SIZE=3D1 FACE=3D"Tahoma">John Rogers&nbsp; </FONT>

<BR><B><FONT SIZE=3D1 FACE=3D"Tahoma">Sent:&nbsp;&nbsp;</FONT></B> <FONT =
SIZE=3D1 FACE=3D"Tahoma">Friday, February 22, 2008 10:26 AM</FONT>

<BR><B><FONT SIZE=3D1 =
FACE=3D"Tahoma">To:&nbsp;&nbsp;&nbsp;&nbsp;</FONT></B> <FONT SIZE=3D1 =
FACE=3D"Tahoma">Sandrine Boulanger; Eric Barrett; Dave Limato; dl-Design =
Review; dl-Marketing</FONT>

<BR><B><FONT SIZE=3D1 =
FACE=3D"Tahoma">Subject:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT>=
</B> <FONT SIZE=3D1 FACE=3D"Tahoma">RE: do we support volumes with =
multiple raid levels luns?</FONT>
</P>

<P><FONT COLOR=3D"#000080" SIZE=3D2 FACE=3D"Arial">Isnt that the idea =
with the raid10 logging lun with raid 5 luns filling in the rest of the =
volume. I think we have tried this in performance testing.</FONT></P>

<P><FONT SIZE=3D2 =
FACE=3D"Tahoma">_____________________________________________<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">From:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Sandrine Boulanger<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Sent:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Friday, February 22, 2008 10:25 AM<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">To:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Eric Barrett; Dave Limato; dl-Design Review; =
dl-Marketing<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Subject:</FONT></B><FONT =
SIZE=3D2 FACE=3D"Tahoma"> RE: do we support volumes with multiple raid =
levels luns?</FONT>
</P>

<P><FONT COLOR=3D"#000080" SIZE=3D2 FACE=3D"Arial">That&#8217;s not my =
point, I know the labels are meaningless; I just want to know if we =
would support customers who mix physical raid levels in the same =
volume.</FONT></P>

<P><FONT SIZE=3D2 =
FACE=3D"Tahoma">_____________________________________________<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">From:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Eric Barrett<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Sent:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Friday, February 22, 2008 10:07 AM<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">To:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Sandrine Boulanger; Dave Limato; dl-Design Review; =
dl-Marketing<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Subject:</FONT></B><FONT =
SIZE=3D2 FACE=3D"Tahoma"> RE: do we support volumes with multiple raid =
levels luns?</FONT>
</P>

<P><FONT SIZE=3D2 FACE=3D"Arial">We should not prevent it, since the =
labels are meaningless.&nbsp; If they had some actual weight in that =
they always accurately reflected the RAID type as given by the array, it =
would make sense to do so.</FONT></P>
<BR>

<P><FONT SIZE=3D1 =
FACE=3D"Tahoma">_____________________________________________ </FONT>

<BR><B><FONT SIZE=3D1 FACE=3D"Tahoma">From: &nbsp;</FONT></B> <FONT =
SIZE=3D1 FACE=3D"Tahoma">Sandrine Boulanger&nbsp; </FONT>

<BR><B><FONT SIZE=3D1 FACE=3D"Tahoma">Sent:&nbsp;&nbsp;</FONT></B> <FONT =
SIZE=3D1 FACE=3D"Tahoma">Friday, February 22, 2008 9:39 AM</FONT>

<BR><B><FONT SIZE=3D1 =
FACE=3D"Tahoma">To:&nbsp;&nbsp;&nbsp;&nbsp;</FONT></B> <FONT SIZE=3D1 =
FACE=3D"Tahoma">Dave Limato; dl-Design Review; dl-Marketing</FONT>

<BR><B><FONT SIZE=3D1 =
FACE=3D"Tahoma">Subject:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT>=
</B> <FONT SIZE=3D1 FACE=3D"Tahoma">RE: do we support volumes with =
multiple raid levels luns?</FONT>
</P>

<P><FONT COLOR=3D"#000080" SIZE=3D2 FACE=3D"Arial">I know there are ways =
to do it, but should we prevent it or not. I want an official =
answer.</FONT>
</P>

<P><FONT SIZE=3D2 =
FACE=3D"Tahoma">_____________________________________________<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">From:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Dave Limato<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Sent:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Friday, February 22, 2008 9:25 AM<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">To:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Sandrine Boulanger; dl-Design Review; dl-Marketing<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Subject:</FONT></B><FONT =
SIZE=3D2 FACE=3D"Tahoma"> RE: do we support volumes with multiple raid =
levels luns?</FONT>
</P>

<P><FONT COLOR=3D"#000080" SIZE=3D2 FACE=3D"Arial">Why yes Sandrine, I =
believe we do, but I think it is somewhat difficult to support because =
of the artificial raid levels.</FONT></P>
<BR>

<P><FONT SIZE=3D2 =
FACE=3D"Tahoma">_____________________________________________<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">From:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Sandrine Boulanger<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Sent:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> Tuesday, February 19, 2008 8:20 PM<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">To:</FONT></B><FONT SIZE=3D2 =
FACE=3D"Tahoma"> dl-Design Review; dl-Marketing<BR>
</FONT><B><FONT SIZE=3D2 FACE=3D"Tahoma">Subject:</FONT></B><FONT =
SIZE=3D2 FACE=3D"Tahoma"> do we support volumes with multiple raid =
levels luns?</FONT>
</P>

<P><FONT SIZE=3D2 FACE=3D"Arial">Our lun labeling has a string for raid =
level as a parameter. Even we can artificially label luns as Raid-5 even =
if the physical read level on disk id Raid-0, do we support mixing =
physical raid levels within the same volume? </FONT></P>

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