| Author |
Message |
Shane
Guest
|
 Posted:
Wed Sep 21, 2005 8:51 am Post subject:
Booting from SAN or local? |
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|
Hi,
We currently have 3 2-node clusters connected via a fibre switch to our SAN.
Our boot disks also boot the server from the SAN.
My question to the group is: What is the preferred method of booting. My
opinion is it would be local with a mirrored disk seeing as booting up off
the SAN is really slow.
Does having the system disk on the SAN slow things down in a SQL and file
sharing cluster environment?
Any ideas would be great as I think doing the disks local would have
performance advantage but I would need to produce something to management.
Cheers
Shane |
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John Toner [MVP]
Guest
|
| Posted:
Wed Sep 21, 2005 4:51 pm Post subject:
Re: Booting from SAN or local? |
|
|
In my experience, it's always better and easier to boot off local mirrored
disks rather than booting from SAN. If you must boot from SAN, you should
always use a local disk for your pagefiles...I'd guess this would be where
things might slow down for you if you've got swap space on a SAN disk.
If you don't have page files on the SAN and the boot disk on your SAN still
seems to slow things down, you might want to look into your SAN as this
should not be the case.
Regards,
John
"Shane" <Shane@discussions.microsoft.com> wrote in message
news:5C85DCB4-77B4-424D-B7E6-78D3F844805C@microsoft.com...
| Quote: | Hi,
We currently have 3 2-node clusters connected via a fibre switch to our
SAN.
Our boot disks also boot the server from the SAN.
My question to the group is: What is the preferred method of booting. My
opinion is it would be local with a mirrored disk seeing as booting up off
the SAN is really slow.
Does having the system disk on the SAN slow things down in a SQL and file
sharing cluster environment?
Any ideas would be great as I think doing the disks local would have
performance advantage but I would need to produce something to management.
Cheers
Shane |
|
|
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|
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Russ Kaufmann [MVP]
Guest
|
| Posted:
Wed Sep 21, 2005 4:51 pm Post subject:
Re: Booting from SAN or local? |
|
|
"Shane" <Shane@discussions.microsoft.com> wrote in message
news:5C85DCB4-77B4-424D-B7E6-78D3F844805C@microsoft.com...
| Quote: | Hi,
We currently have 3 2-node clusters connected via a fibre switch to our
SAN.
Our boot disks also boot the server from the SAN.
My question to the group is: What is the preferred method of booting. My
opinion is it would be local with a mirrored disk seeing as booting up off
the SAN is really slow.
|
The cost of internal disks is considerably cheaper than the cost of SAN
disks, too, so I agree.
I would use a mirrored disk set for the operating system and a single small
disk (no need for redundancy) for the pagefile.
--
Russ Kaufmann
MVP - Windows Server - Clustering
http://www.clusterhelp.com - Cluster Website
http://msmvps.com/clusterhelp - New Blog
http://spaces.msn.com/members/russkaufmann - Old Blog |
|
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|
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Matt Povey
Guest
|
| Posted:
Thu Sep 22, 2005 12:50 pm Post subject:
RE: Booting from SAN or local? |
|
|
Shane,
I disagree with the other guys here. While I see their points, there are
specific situations where using boot from SAN for Windows servers is
extrememly beneficial.
In particular, if you're operating in one of the following environments,
it's very helpful :
1) Rapid deployment \ blade environments - SAN boot volumes can be
re-assigned \ copied dynamically within the SAN fabric aiding fast deployment
and recovery from localised hardware failures
2) DR. By synchronously replicating a boot volume across sites, you can
massively simplify your DR process though the use of cold standby server.
Answers to your other questions below :
"Shane" wrote:
| Quote: | My question to the group is: What is the preferred method of booting. My
opinion is it would be local with a mirrored disk seeing as booting up off
the SAN is really slow.
|
You really shouldn't be seeing any performance problems booting from SAN. If
performance from your data volumes is adequate but the boot disk is poor I'd
look at the BIOS currently installed on your HBA. Is your environment
qualified end to end by your SAN vendor?
You really shouldn't have your page file on SAN attached disk although this
is really for availability\reliability reasons rather than performance
(although it's a waste of SAN resources to have the page file there).
| Quote: |
Does having the system disk on the SAN slow things down in a SQL and file
sharing cluster environment?
|
It certainly shouldn't do. Once booted, a Windows server with sufficient RAM
doesn't really touch the boot disk. Even if it did, access to SAN attached
disk should be as fast and low latency as DAS. Note that sync rep, SAN based
mirrors , snaphots etc. can have an effect on performance.
The clusters I've got booting from SAN (file, print and Exchange all in AAAP
conf.) all perform just fine.
| Quote: | Any ideas would be great as I think doing the disks local would have
performance advantage but I would need to produce something to management.
|
There's no reason to think that you'll get a useful performance advantage
from DAS (depending on the configuration of your SAN of course) and you'll
likely lose significant functionality by switching to local disk.
You should read the following :
http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/clustering/storbp.mspx
http://support.microsoft.com/default.aspx?scid=kb;en-us;305547
http://support.microsoft.com/kb/309186/EN-US/
http://support.microsoft.com/kb/301647/
http://support.microsoft.com/default.aspx?scid=kb;en-us;304415
Good luck,
Matt Povey |
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|
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Russ Kaufmann [MVP]
Guest
|
| Posted:
Thu Sep 22, 2005 8:50 pm Post subject:
Re: Booting from SAN or local? |
|
|
"Matt Povey" <Matt Povey@discussions.microsoft.com> wrote in message
news:384D6D50-CF92-48B8-A2F8-48C61AC8EA33@microsoft.com...
| Quote: | 1) Rapid deployment \ blade environments - SAN boot volumes can be
re-assigned \ copied dynamically within the SAN fabric aiding fast
deployment
and recovery from localised hardware failures
|
That is a nice bit of functionality, but does not result in performance
increases unless the blades are using slow drives.
| Quote: | 2) DR. By synchronously replicating a boot volume across sites, you can
massively simplify your DR process though the use of cold standby server.
|
An excellent point if you have geographically disperse SANs that are
configured to synch. I agree that it is a great benefit.
| Quote: | My question to the group is: What is the preferred method of booting.
My
opinion is it would be local with a mirrored disk seeing as booting up
off
the SAN is really slow.
You really shouldn't be seeing any performance problems booting from SAN.
If
performance from your data volumes is adequate but the boot disk is poor
I'd
look at the BIOS currently installed on your HBA. Is your environment
qualified end to end by your SAN vendor?
|
If you look at this regarding strict I/O performance and data transfer,
which is capable of delivering uncached data quicker? I would counter that
the SAN throughput, even using multipathing, will be slower than using local
disk connecting using a local bus.
| Quote: | You really shouldn't have your page file on SAN attached disk although
this
is really for availability\reliability reasons rather than performance
(although it's a waste of SAN resources to have the page file there).
|
Again, this is also a performance issue. Page file swaps will be much
quicker across a local bus than across the SAN fabric.
| Quote: | Does having the system disk on the SAN slow things down in a SQL and file
sharing cluster environment?
It certainly shouldn't do. Once booted, a Windows server with sufficient
RAM
doesn't really touch the boot disk. Even if it did, access to SAN attached
disk should be as fast and low latency as DAS. Note that sync rep, SAN
based
mirrors , snaphots etc. can have an effect on performance.
|
SANs utilize extremely high amounts of RAM for caching, so in most "read"
cases, cache hits more than make up for the lesser transfer rates. In most
cases, with file and SQL access, you will see other bottlenecks to high
performance.
| Quote: | Any ideas would be great as I think doing the disks local would have
performance advantage but I would need to produce something to
management.
There's no reason to think that you'll get a useful performance advantage
from DAS (depending on the configuration of your SAN of course) and you'll
likely lose significant functionality by switching to local disk.
|
I disagree with Matt on this one. DAS is capable of much greater transfer
rates than SAN attached drives.
--
Russ Kaufmann
MVP - Windows Server - Clustering
http://www.clusterhelp.com - Cluster Website
http://msmvps.com/clusterhelp - New Blog
http://spaces.msn.com/members/russkaufmann - Old Blog |
|
| Back to top |
|
|
Ryan Sokolowski [MVP - Av
Guest
|
| Posted:
Wed Sep 28, 2005 12:50 am Post subject:
Re: Booting from SAN or local? |
|
|
I'll add this point also. Make sure you're using the correct (read:
STORPORT) drivers for your HBAs and ensure they're configured properly
(firmware, settings, etc.). Work with your storage vendor if you wish /
must.
Since the system disks are SAN-based, everything now depends on the
performance of your Fibre Channel zoning, HBAs, drivers, physical layer
(cabling), etc....
--
Ryan Sokolowski
MVP - Windows Server - Clustering
MCSE, CCNA, CCDA, BCFP
Avanade
http://www.Avanade.com
"A troubleshooter's best tool is the Event Viewer and understanding the
events and messages contained therein."
This posting is provided "AS IS" with no warranties, and confers no rights.
"Russ Kaufmann [MVP]" <russ@exchangemct.com> wrote in message
news:%23sh18S6vFHA.1988@TK2MSFTNGP10.phx.gbl...
| Quote: | "Matt Povey" <Matt Povey@discussions.microsoft.com> wrote in message
news:384D6D50-CF92-48B8-A2F8-48C61AC8EA33@microsoft.com...
1) Rapid deployment \ blade environments - SAN boot volumes can be
re-assigned \ copied dynamically within the SAN fabric aiding fast
deployment
and recovery from localised hardware failures
That is a nice bit of functionality, but does not result in performance
increases unless the blades are using slow drives.
2) DR. By synchronously replicating a boot volume across sites, you can
massively simplify your DR process though the use of cold standby server.
An excellent point if you have geographically disperse SANs that are
configured to synch. I agree that it is a great benefit.
My question to the group is: What is the preferred method of booting.
My
opinion is it would be local with a mirrored disk seeing as booting up
off
the SAN is really slow.
You really shouldn't be seeing any performance problems booting from SAN.
If
performance from your data volumes is adequate but the boot disk is poor
I'd
look at the BIOS currently installed on your HBA. Is your environment
qualified end to end by your SAN vendor?
If you look at this regarding strict I/O performance and data transfer,
which is capable of delivering uncached data quicker? I would counter that
the SAN throughput, even using multipathing, will be slower than using
local disk connecting using a local bus.
You really shouldn't have your page file on SAN attached disk although
this
is really for availability\reliability reasons rather than performance
(although it's a waste of SAN resources to have the page file there).
Again, this is also a performance issue. Page file swaps will be much
quicker across a local bus than across the SAN fabric.
Does having the system disk on the SAN slow things down in a SQL and
file
sharing cluster environment?
It certainly shouldn't do. Once booted, a Windows server with sufficient
RAM
doesn't really touch the boot disk. Even if it did, access to SAN
attached
disk should be as fast and low latency as DAS. Note that sync rep, SAN
based
mirrors , snaphots etc. can have an effect on performance.
SANs utilize extremely high amounts of RAM for caching, so in most "read"
cases, cache hits more than make up for the lesser transfer rates. In most
cases, with file and SQL access, you will see other bottlenecks to high
performance.
Any ideas would be great as I think doing the disks local would have
performance advantage but I would need to produce something to
management.
There's no reason to think that you'll get a useful performance advantage
from DAS (depending on the configuration of your SAN of course) and
you'll
likely lose significant functionality by switching to local disk.
I disagree with Matt on this one. DAS is capable of much greater transfer
rates than SAN attached drives.
--
Russ Kaufmann
MVP - Windows Server - Clustering
http://www.clusterhelp.com - Cluster Website
http://msmvps.com/clusterhelp - New Blog
http://spaces.msn.com/members/russkaufmann - Old Blog
|
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|
| Back to top |
|
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Chuck Timon [MSFT]
Guest
|
| Posted:
Wed Sep 28, 2005 8:51 pm Post subject:
Re: Booting from SAN or local? |
|
|
Be sure you review
http://support.microsoft.com/default.aspx?scid=kb;[LN];305547 and understand
that booting from a SAN must be supported by the hardware vendor or
Microsoft will not support it.
--
Chuck Timon, Jr.
Microsoft Corporation
CCS Beta Engineer
This posting is provided "AS IS" with no
warranties, and confers no rights.
"Ryan Sokolowski [MVP - Avanade]" <ryan@newsgroups.avanade.com> wrote in
message news:%23CtRmy6wFHA.1488@TK2MSFTNGP10.phx.gbl...
| Quote: | I'll add this point also. Make sure you're using the correct (read:
STORPORT) drivers for your HBAs and ensure they're configured properly
(firmware, settings, etc.). Work with your storage vendor if you wish /
must.
Since the system disks are SAN-based, everything now depends on the
performance of your Fibre Channel zoning, HBAs, drivers, physical layer
(cabling), etc....
--
Ryan Sokolowski
MVP - Windows Server - Clustering
MCSE, CCNA, CCDA, BCFP
Avanade
http://www.Avanade.com
"A troubleshooter's best tool is the Event Viewer and understanding the
events and messages contained therein."
This posting is provided "AS IS" with no warranties, and confers no
rights.
"Russ Kaufmann [MVP]" <russ@exchangemct.com> wrote in message
news:%23sh18S6vFHA.1988@TK2MSFTNGP10.phx.gbl...
"Matt Povey" <Matt Povey@discussions.microsoft.com> wrote in message
news:384D6D50-CF92-48B8-A2F8-48C61AC8EA33@microsoft.com...
1) Rapid deployment \ blade environments - SAN boot volumes can be
re-assigned \ copied dynamically within the SAN fabric aiding fast
deployment
and recovery from localised hardware failures
That is a nice bit of functionality, but does not result in performance
increases unless the blades are using slow drives.
2) DR. By synchronously replicating a boot volume across sites, you can
massively simplify your DR process though the use of cold standby
server.
An excellent point if you have geographically disperse SANs that are
configured to synch. I agree that it is a great benefit.
My question to the group is: What is the preferred method of booting.
My
opinion is it would be local with a mirrored disk seeing as booting up
off
the SAN is really slow.
You really shouldn't be seeing any performance problems booting from
SAN. If
performance from your data volumes is adequate but the boot disk is poor
I'd
look at the BIOS currently installed on your HBA. Is your environment
qualified end to end by your SAN vendor?
If you look at this regarding strict I/O performance and data transfer,
which is capable of delivering uncached data quicker? I would counter
that the SAN throughput, even using multipathing, will be slower than
using local disk connecting using a local bus.
You really shouldn't have your page file on SAN attached disk although
this
is really for availability\reliability reasons rather than performance
(although it's a waste of SAN resources to have the page file there).
Again, this is also a performance issue. Page file swaps will be much
quicker across a local bus than across the SAN fabric.
Does having the system disk on the SAN slow things down in a SQL and
file
sharing cluster environment?
It certainly shouldn't do. Once booted, a Windows server with sufficient
RAM
doesn't really touch the boot disk. Even if it did, access to SAN
attached
disk should be as fast and low latency as DAS. Note that sync rep, SAN
based
mirrors , snaphots etc. can have an effect on performance.
SANs utilize extremely high amounts of RAM for caching, so in most "read"
cases, cache hits more than make up for the lesser transfer rates. In
most cases, with file and SQL access, you will see other bottlenecks to
high performance.
Any ideas would be great as I think doing the disks local would have
performance advantage but I would need to produce something to
management.
There's no reason to think that you'll get a useful performance
advantage
from DAS (depending on the configuration of your SAN of course) and
you'll
likely lose significant functionality by switching to local disk.
I disagree with Matt on this one. DAS is capable of much greater transfer
rates than SAN attached drives.
--
Russ Kaufmann
MVP - Windows Server - Clustering
http://www.clusterhelp.com - Cluster Website
http://msmvps.com/clusterhelp - New Blog
http://spaces.msn.com/members/russkaufmann - Old Blog
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