I was hoping that someone could point me to some good documentation on
selecting an optimum RAID configuration. While performing heavy updates
during upgrades - I've noticed dramatic performance difference between RAID
1 and RAID 5 for the transaction log.
It seems that it is less important for the data files themselves (RAID 5
doesn't seem to hurt that much).
Does this make sense where the RAID Configuration for the T-Log is more
important than the Data?
If someone could shed some light on this or point me to some good
documantation - I would greatly appreciate it.
Thanks in advanceRaid 5 performs very poorly on writes as does hp/compaq's ADG (Advanced data
guarding).
If your database is mainly reads then raid 5 is ok for the datafiles.
Also consider that if a disk fails and the array is having to construct a
phantom disk on the fly then the performance of your system will probably
make it unusable.
It's worth pulling a disk on a system before it goes live and practice the
recovery.
Personally I use a raid 10 array of 4 disks for my log (and raid 10 arrays
for my data too). A mirror pair may do for your log.
Paul
"TJT" <TJT@.nospam.com> wrote in message
news:uDWYpug5FHA.1248@.TK2MSFTNGP14.phx.gbl...
>I was hoping that someone could point me to some good documentation on
> selecting an optimum RAID configuration. While performing heavy updates
> during upgrades - I've noticed dramatic performance difference between
> RAID
> 1 and RAID 5 for the transaction log.
> It seems that it is less important for the data files themselves (RAID 5
> doesn't seem to hurt that much).
> Does this make sense where the RAID Configuration for the T-Log is more
> important than the Data?
> If someone could shed some light on this or point me to some good
> documantation - I would greatly appreciate it.
> Thanks in advance
>|||This is a multi-part message in MIME format.
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I've always found this website to be a good RAID level overview (even
though it's a vendor website):
http://www.acnc.com/raid.html
It's not very detailed, just brief pros & cons and how the RAID level is
constructed, but it's good info nonetheless.
--
*mike hodgson*
blog: http://sqlnerd.blogspot.com
TJT wrote:
>I was hoping that someone could point me to some good documentation on
>selecting an optimum RAID configuration. While performing heavy updates
>during upgrades - I've noticed dramatic performance difference between RAID
>1 and RAID 5 for the transaction log.
>It seems that it is less important for the data files themselves (RAID 5
>doesn't seem to hurt that much).
>Does this make sense where the RAID Configuration for the T-Log is more
>important than the Data?
>If someone could shed some light on this or point me to some good
>documantation - I would greatly appreciate it.
>Thanks in advance
>
>
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<tt>I've always found this website to be a good RAID level overview
(even though it's a vendor website):<br>
<a class="moz-txt-link-freetext" href="http://links.10026.com/?link=http://www.acnc.com/raid.html</a><br>">http://www.acnc.com/raid.html">http://www.acnc.com/raid.html</a><br>
<br>
It's not very detailed, just brief pros & cons and how the RAID
level is constructed, but it's good info nonetheless.<br>
</tt>
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<p><span lang="en-au"><font face="Tahoma" size="2">--<br>
</font></span> <b><span lang="en-au"><font face="Tahoma" size="2">mike
hodgson</font></span></b><span lang="en-au"><br>
<font face="Tahoma" size="2">blog:</font><font face="Tahoma" size="2"> <a
href="http://links.10026.com/?link=http://sqlnerd.blogspot.com</a></font></span>">http://sqlnerd.blogspot.com">http://sqlnerd.blogspot.com</a></font></span>
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<br>
<br>
TJT wrote:
<blockquote cite="miduDWYpug5FHA.1248@.TK2MSFTNGP14.phx.gbl" type="cite">
<pre wrap="">I was hoping that someone could point me to some good documentation on
selecting an optimum RAID configuration. While performing heavy updates
during upgrades - I've noticed dramatic performance difference between RAID
1 and RAID 5 for the transaction log.
It seems that it is less important for the data files themselves (RAID 5
doesn't seem to hurt that much).
Does this make sense where the RAID Configuration for the T-Log is more
important than the Data?
If someone could shed some light on this or point me to some good
documantation - I would greatly appreciate it.
Thanks in advance
</pre>
</blockquote>
</body>
</html>
--060704050306020201010502--|||RAID5 is terrible for heavily updated data, and the Transaction Log is the
prototypical worst case. Go for RAID 1. For database files/filegroups it
really depends on the update load. In general the feeling has been that
RAID 10 (aka 1+0) is better for databases since you get maximum performance
and availability. But if you have lightly updated tables then RAID 5 is
going to be OK.
If I remember correctly Kalen Delaney's "Inside SQL Server 2000" book has a
good discussion about this.
--
Hal Berenson, President
PredictableIT, LLC
www.predictableit.com
"Mike Hodgson" <mike.hodgson@.mallesons.nospam.com> wrote in message
news:e6mn%23ll5FHA.1276@.TK2MSFTNGP09.phx.gbl...
> I've always found this website to be a good RAID level overview (even
> though it's a vendor website):
> http://www.acnc.com/raid.html
> It's not very detailed, just brief pros & cons and how the RAID level is
> constructed, but it's good info nonetheless.
> --
> *mike hodgson*
> blog: http://sqlnerd.blogspot.com
>
> TJT wrote:
>>I was hoping that someone could point me to some good documentation on
>>selecting an optimum RAID configuration. While performing heavy updates
>>during upgrades - I've noticed dramatic performance difference between
>>RAID
>>1 and RAID 5 for the transaction log.
>>It seems that it is less important for the data files themselves (RAID 5
>>doesn't seem to hurt that much).
>>Does this make sense where the RAID Configuration for the T-Log is more
>>important than the Data?
>>If someone could shed some light on this or point me to some good
>>documantation - I would greatly appreciate it.
>>Thanks in advance
>>
>>
>
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