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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=843192619-05062007>True. I missed that on the RAID 0 as opposed to
RAID 1.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=843192619-05062007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=843192619-05062007>Also, you would probable be surprised at the number
of places that use the RAID 6 or RAID ADG in a mirrored
configuration. It is not a fast or speedy solution. Remember
that RAID 6 or RAID ADG is the SLOWEST RAID as far as performance is
concerned. With RAID 10 you still open yourself up to vulnerability when a
drive fails on your stripeset which causes your stripeset to fail. Since
it is mirrored you are fine unless you have a failure on your mirrored
stripeset. Personally, I don't like to use RAID 0 at anytime because it
has no resiliency when it comes to disk failures. I would rather have the
RAID 5 at a minimum for any single disk LUN and then use RAID 1 for additional
redundancy. But generally I work with companies that are willing to spend
the money for that configuration along with having controllers with the maximum
read/write cache to compensate for the speed.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=843192619-05062007></SPAN></FONT> </DIV><BR>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> Jeremy Fowler
[mailto:jeremy.f76@gmail.com] <BR><B>Sent:</B> Tuesday, June 05, 2007 2:17
PM<BR><B>To:</B> Phil Thayer<BR><B>Cc:</B> kclug@kclug.org<BR><B>Subject:</B>
Re: SATA PT2<BR></FONT><BR></DIV>
<DIV></DIV>RAID 0 is a striped set, no parity.<BR>RAID 1 is a mirrored
set.<BR><BR>So RAID60 would be two RAID 6 arrays striped
together.<BR><BR>RAID61 would be two mirrored RAID 6 arrays... I could see
maybe why you would strip two RAID 6 arrays to increase performance, but that
would be incredibly costly and I would say complete overkill. If you
need redundancy and speed is a high priority, you might as well do RAID10, a
stripped set of mirrored drives. However, if you a have a limited number of
drives and needed the most storage size by reducing the ratio of parity drives
and disk I/O performance isn't too important then RAID 5/6 is your answer.
<BR><BR>
<DIV><SPAN class=gmail_quote>On 6/5/07, <B class=gmail_sendername>Phil
Thayer</B> <<A
href="mailto:phil.thayer@vitalsite.com">phil.thayer@vitalsite.com</A>>
wrote:</SPAN>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">If
you do that you need to make sure that the controller will support<BR>RAID 6
or RAID ADG. This is simply a RAID 5 with an additional
parity<BR>disk implemented. This reduces the risk of failure of
the entire RAID<BR>if a single disk fails. The RAID will simply
function as if it were a<BR>RAID 5 until the failed disk is physically
replaced and the RAID 6 or<BR>RAID ADG is rebuilt.<BR><BR>As an alternative,
if you have a controller that does not have RAID 6 or <BR>RAID ADG, then you
can use RAID 5 with a spare disk set aside for use as<BR>a spareset in case
of a failure. This does not eliminate the risk in<BR>case of a
single disk failure but it reduces it to the time required to <BR>rebuild
the RAID using the spareset as opposed to the time it takes to<BR>physically
replace a drive in a degraded RAID 5. If you suffer a second<BR>disk drive
failure during the time that the RAID 5 is rebuilding after <BR>the first
disk drive failure, then you will loose your entire RAID.<BR><BR>The
ultimate high availability configuration would be RAID
60+. This<BR>would be two RAID 6 with their own sparesets
assigned, mirrored to each <BR>other. However, be prepared to
loose a larger percentage of your raw<BR>disk drive space. You
will loose the equivalent of:<BR><BR>Two disk drives for each RAID 6
used<BR>Two disk drives for each RAID 6 for redundant sparesets <BR>One raid
6 with the mirroring<BR><BR>I really don't expect that you would build
something like that for a<BR>home server but I figured I would throw all
that out there just in case<BR>you had more money that you know what to do
with and want to make sure <BR>the data on your server is safe from
failure.<BR><BR>Phil<BR><BR>> -----Original Message-----<BR>> From: <A
href="mailto:kclug-bounces@kclug.org">kclug-bounces@kclug.org</A><BR>>
[mailto:<A href="mailto:kclug-bounces@kclug.org">
kclug-bounces@kclug.org</A>] On Behalf Of Luke-Jr<BR>> Sent: Tuesday,
June 05, 2007 9:20 AM<BR>> To: <A
href="mailto:kclug@kclug.org">kclug@kclug.org</A><BR>> Subject: Re: SATA
PT2<BR>><BR>> On Tuesday 05 June 2007 09:11, Phil Thayer wrote:
<BR>> > Not to mention that with the recent SATA drive sizes to
get<BR>> 1TB of SATA<BR>> > would only take 2
drive. However, if you want to use a<BR>>
multi-channel<BR>> > SATA controller with raid you will want to use
smaller <BR>> drives (like 4 x<BR>> > 300 or 8 X 250) so you don't
loose too much capacity to parity.<BR>><BR>> With 8 drives, I'd
probably want to make 2 parity for a<BR>> server... As unlikely<BR>>
as it is for 2 drives to fail at once, that chance does <BR>> increase
with # of<BR>> drives.<BR>>
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