Determine Disk Block Size ?

I have a SQL Server 2000 Enterprise database that processes 300
transactions/sec, approximately 300 users, and 250 GB in size. How can I
determine the the appropriate disk block size that should be on my system.
Thanks,
Unless you have an overriding reason, go with the hardware manufacturer's
recommendations. These are typically the default settings. Changing the
NTFS block size usually has no measurable effect on system performance.
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com
I support the Professional Association for SQL Server
www.sqlpass.org
"Joe K." <Joe K.@.discussions.microsoft.com> wrote in message
news:B77A9710-86AA-4319-B539-6F65D91E5ECA@.microsoft.com...
> I have a SQL Server 2000 Enterprise database that processes 300
> transactions/sec, approximately 300 users, and 250 GB in size. How can I
> determine the the appropriate disk block size that should be on my system.
> Thanks,
>
|||Hi
Rather make sure that your drives are configured correctly.
Make sure your logs on RAID-10, and preferably your data on a separate
RAID-10 volume. RAID-5 hurts more than it helps.
As Geoff said, block size is not important, but getting maximum IO
throughput is.
Regards
Mike Epprecht, Microsoft SQL Server MVP
Zurich, Switzerland
IM: mike@.epprecht.net
MVP Program: http://www.microsoft.com/mvp
Blog: http://www.msmvps.com/epprecht/
"Geoff N. Hiten" <SRDBA@.Careerbuilder.com> wrote in message
news:uhfJBgXBFHA.2180@.TK2MSFTNGP12.phx.gbl...[vbcol=seagreen]
> Unless you have an overriding reason, go with the hardware manufacturer's
> recommendations. These are typically the default settings. Changing the
> NTFS block size usually has no measurable effect on system performance.
> --
> Geoff N. Hiten
> Microsoft SQL Server MVP
> Senior Database Administrator
> Careerbuilder.com
> I support the Professional Association for SQL Server
> www.sqlpass.org
> "Joe K." <Joe K.@.discussions.microsoft.com> wrote in message
> news:B77A9710-86AA-4319-B539-6F65D91E5ECA@.microsoft.com...
I[vbcol=seagreen]
system.
>
|||Hi
Rather make sure that your drives are configured correctly.
Make sure your logs on RAID-10, and preferably your data on a separate
RAID-10 volume. RAID-5 hurts more than it helps.
As Geoff said, block size is not important, but getting maximum IO
throughput is.
Regards
Mike Epprecht, Microsoft SQL Server MVP
Zurich, Switzerland
IM: mike@.epprecht.net
MVP Program: http://www.microsoft.com/mvp
Blog: http://www.msmvps.com/epprecht/
"Geoff N. Hiten" <SRDBA@.Careerbuilder.com> wrote in message
news:uhfJBgXBFHA.2180@.TK2MSFTNGP12.phx.gbl...[vbcol=seagreen]
> Unless you have an overriding reason, go with the hardware manufacturer's
> recommendations. These are typically the default settings. Changing the
> NTFS block size usually has no measurable effect on system performance.
> --
> Geoff N. Hiten
> Microsoft SQL Server MVP
> Senior Database Administrator
> Careerbuilder.com
> I support the Professional Association for SQL Server
> www.sqlpass.org
> "Joe K." <Joe K.@.discussions.microsoft.com> wrote in message
> news:B77A9710-86AA-4319-B539-6F65D91E5ECA@.microsoft.com...
I[vbcol=seagreen]
system.
>
|||Not that I disagree with the RAID-10 argument, I don't; however, I do
disagree with your comments about NTFS Cluster Sizes (a.k.a., block size).
The MS SQL Server Operations Manual makes a recommendation of using 64-KB
cluster sizes. We have done so with a dramatic total disk I/O throughput.
It makes sense. SQL Server reads and writes data in 8KB data pages, but
issues Scatter-Gather I/O requests in 4 or more Extents (8 x 8KB pages)
simultaneously. If your block sizes are on these 8KB boundaries, SQL Server
Disk I/O requests can be more efficient.
Your biggest disk throughput bottleneck is total number of I/O Operations a
single spindle can handle. You're throughput will be based on type of
access, sequential versus random, and the size of each request. Optimizing
the request sizes coupled with a fixed maximum number of I/O Ops, should
make your system as efficient as possible.
Nevertheless, and along the same lines as the RAID arguments already
presented, this is also suggested from the Operations Manual: more smaller
disks are more efficient than fewer larger disks. This would come into play
in the 0 part of the RAID-10 argument. Striping allows more physical
spindles to fulfill requests, each one capable of servicing a theoretical
maximum number of I/O Ops. Furthermore, more files per Filegroup will spawn
additional disk threads per request. This coupled with number of disks can
greatly improve throughput.
Sincerely,
Anthony Thomas

"Mike Epprecht (SQL MVP)" <mike@.epprecht.net> wrote in message
news:uY2FhGsBFHA.3840@.tk2msftngp13.phx.gbl...
Hi
Rather make sure that your drives are configured correctly.
Make sure your logs on RAID-10, and preferably your data on a separate
RAID-10 volume. RAID-5 hurts more than it helps.
As Geoff said, block size is not important, but getting maximum IO
throughput is.
Regards
Mike Epprecht, Microsoft SQL Server MVP
Zurich, Switzerland
IM: mike@.epprecht.net
MVP Program: http://www.microsoft.com/mvp
Blog: http://www.msmvps.com/epprecht/
"Geoff N. Hiten" <SRDBA@.Careerbuilder.com> wrote in message
news:uhfJBgXBFHA.2180@.TK2MSFTNGP12.phx.gbl...[vbcol=seagreen]
> Unless you have an overriding reason, go with the hardware manufacturer's
> recommendations. These are typically the default settings. Changing the
> NTFS block size usually has no measurable effect on system performance.
> --
> Geoff N. Hiten
> Microsoft SQL Server MVP
> Senior Database Administrator
> Careerbuilder.com
> I support the Professional Association for SQL Server
> www.sqlpass.org
> "Joe K." <Joe K.@.discussions.microsoft.com> wrote in message
> news:B77A9710-86AA-4319-B539-6F65D91E5ECA@.microsoft.com...
I[vbcol=seagreen]
system.
>
|||An I agree with your comments except for the last one:[vbcol=seagreen]
Furthermore, more files per Filegroup will spawn
additional disk threads per request.
<<
That was true with 7.0 but is not necessarily true with SQL2000. In 2000
Sql Server can spawn multiple threads to read a single file as well. So
just having multiple files does not mean it will be more effecient or spawn
more threads than a single file.
Andrew J. Kelly SQL MVP
"Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
news:ep16rw1BFHA.3592@.TK2MSFTNGP09.phx.gbl...
> Not that I disagree with the RAID-10 argument, I don't; however, I do
> disagree with your comments about NTFS Cluster Sizes (a.k.a., block size).
> The MS SQL Server Operations Manual makes a recommendation of using 64-KB
> cluster sizes. We have done so with a dramatic total disk I/O throughput.
> It makes sense. SQL Server reads and writes data in 8KB data pages, but
> issues Scatter-Gather I/O requests in 4 or more Extents (8 x 8KB pages)
> simultaneously. If your block sizes are on these 8KB boundaries, SQL
> Server
> Disk I/O requests can be more efficient.
> Your biggest disk throughput bottleneck is total number of I/O Operations
> a
> single spindle can handle. You're throughput will be based on type of
> access, sequential versus random, and the size of each request.
> Optimizing
> the request sizes coupled with a fixed maximum number of I/O Ops, should
> make your system as efficient as possible.
> Nevertheless, and along the same lines as the RAID arguments already
> presented, this is also suggested from the Operations Manual: more smaller
> disks are more efficient than fewer larger disks. This would come into
> play
> in the 0 part of the RAID-10 argument. Striping allows more physical
> spindles to fulfill requests, each one capable of servicing a theoretical
> maximum number of I/O Ops. Furthermore, more files per Filegroup will
> spawn
> additional disk threads per request. This coupled with number of disks
> can
> greatly improve throughput.
> Sincerely,
>
> Anthony Thomas
>
> --
> "Mike Epprecht (SQL MVP)" <mike@.epprecht.net> wrote in message
> news:uY2FhGsBFHA.3840@.tk2msftngp13.phx.gbl...
> Hi
> Rather make sure that your drives are configured correctly.
> Make sure your logs on RAID-10, and preferably your data on a separate
> RAID-10 volume. RAID-5 hurts more than it helps.
> As Geoff said, block size is not important, but getting maximum IO
> throughput is.
> Regards
> --
> Mike Epprecht, Microsoft SQL Server MVP
> Zurich, Switzerland
> IM: mike@.epprecht.net
> MVP Program: http://www.microsoft.com/mvp
> Blog: http://www.msmvps.com/epprecht/
> "Geoff N. Hiten" <SRDBA@.Careerbuilder.com> wrote in message
> news:uhfJBgXBFHA.2180@.TK2MSFTNGP12.phx.gbl...
> I
> system.
>
|||I just read that SS2K SE spawns Read Ahead requests in 4xExtents, 128 KB
chunks, and spawns a thread per data file in each Filegroup. It also
mentioned that EE can exceed the number of concurrent extents per request
and managed the thread spawning more efficiently. But, damn if I can't
remember where I came across the information.
Anthony Thomas

"Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
news:uNjLEV5BFHA.2180@.TK2MSFTNGP10.phx.gbl...
An I agree with your comments except for the last one:[vbcol=seagreen]
Furthermore, more files per Filegroup will spawn
additional disk threads per request.
<<
That was true with 7.0 but is not necessarily true with SQL2000. In 2000
Sql Server can spawn multiple threads to read a single file as well. So
just having multiple files does not mean it will be more effecient or spawn
more threads than a single file.
Andrew J. Kelly SQL MVP
"Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
news:ep16rw1BFHA.3592@.TK2MSFTNGP09.phx.gbl...
> Not that I disagree with the RAID-10 argument, I don't; however, I do
> disagree with your comments about NTFS Cluster Sizes (a.k.a., block size).
> The MS SQL Server Operations Manual makes a recommendation of using 64-KB
> cluster sizes. We have done so with a dramatic total disk I/O throughput.
> It makes sense. SQL Server reads and writes data in 8KB data pages, but
> issues Scatter-Gather I/O requests in 4 or more Extents (8 x 8KB pages)
> simultaneously. If your block sizes are on these 8KB boundaries, SQL
> Server
> Disk I/O requests can be more efficient.
> Your biggest disk throughput bottleneck is total number of I/O Operations
> a
> single spindle can handle. You're throughput will be based on type of
> access, sequential versus random, and the size of each request.
> Optimizing
> the request sizes coupled with a fixed maximum number of I/O Ops, should
> make your system as efficient as possible.
> Nevertheless, and along the same lines as the RAID arguments already
> presented, this is also suggested from the Operations Manual: more smaller
> disks are more efficient than fewer larger disks. This would come into
> play
> in the 0 part of the RAID-10 argument. Striping allows more physical
> spindles to fulfill requests, each one capable of servicing a theoretical
> maximum number of I/O Ops. Furthermore, more files per Filegroup will
> spawn
> additional disk threads per request. This coupled with number of disks
> can
> greatly improve throughput.
> Sincerely,
>
> Anthony Thomas
>
> --
> "Mike Epprecht (SQL MVP)" <mike@.epprecht.net> wrote in message
> news:uY2FhGsBFHA.3840@.tk2msftngp13.phx.gbl...
> Hi
> Rather make sure that your drives are configured correctly.
> Make sure your logs on RAID-10, and preferably your data on a separate
> RAID-10 volume. RAID-5 hurts more than it helps.
> As Geoff said, block size is not important, but getting maximum IO
> throughput is.
> Regards
> --
> Mike Epprecht, Microsoft SQL Server MVP
> Zurich, Switzerland
> IM: mike@.epprecht.net
> MVP Program: http://www.microsoft.com/mvp
> Blog: http://www.msmvps.com/epprecht/
> "Geoff N. Hiten" <SRDBA@.Careerbuilder.com> wrote in message
> news:uhfJBgXBFHA.2180@.TK2MSFTNGP12.phx.gbl...
> I
> system.
>
|||Not sure which document that came from either. The read ahead is actually
dynamic in the size of each read ahead request based somewhat on how
fragmented the data is. It can be 8K or 128K, it just depends on if it is
possible to do so or not. Most of the documentation for 2000 is wrong in
that it may state you need multiple files to spawn multiple threads. That
is definitely not the case and this is supposed to be fixed in the 2005
docs. Yes it can spawn a thread of each file but it is not limited to a
single thread per file. Even with a single file it is possible to spawn
multiple threads to read the same file. Here is what looks like a very
interesting article on IO in 2000. I haven't had a chance to read it yet
(hope to in the next few days) but it looks very promising.
http://www.microsoft.com/technet/pro...lIObasics.mspx
Andrew J. Kelly SQL MVP
"Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
news:u8xc256BFHA.1564@.TK2MSFTNGP09.phx.gbl...
>I just read that SS2K SE spawns Read Ahead requests in 4xExtents, 128 KB
> chunks, and spawns a thread per data file in each Filegroup. It also
> mentioned that EE can exceed the number of concurrent extents per request
> and managed the thread spawning more efficiently. But, damn if I can't
> remember where I came across the information.
> Anthony Thomas
>
> --
> "Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
> news:uNjLEV5BFHA.2180@.TK2MSFTNGP10.phx.gbl...
> An I agree with your comments except for the last one:
> Furthermore, more files per Filegroup will spawn
> additional disk threads per request.
> <<
> That was true with 7.0 but is not necessarily true with SQL2000. In 2000
> Sql Server can spawn multiple threads to read a single file as well. So
> just having multiple files does not mean it will be more effecient or
> spawn
> more threads than a single file.
>
> --
> Andrew J. Kelly SQL MVP
>
> "Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
> news:ep16rw1BFHA.3592@.TK2MSFTNGP09.phx.gbl...
>
|||As always, thanks Andrew. Yes, I am well aware of having to "filter" read
information and make judgement calls on the sources reliability. The
article I read seemed respectable, though. If I come across it, I'll post a
"What's up" response.
Sincerely,
Anthony Thomas

"Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
news:ewn3Iz7BFHA.2260@.TK2MSFTNGP14.phx.gbl...
Not sure which document that came from either. The read ahead is actually
dynamic in the size of each read ahead request based somewhat on how
fragmented the data is. It can be 8K or 128K, it just depends on if it is
possible to do so or not. Most of the documentation for 2000 is wrong in
that it may state you need multiple files to spawn multiple threads. That
is definitely not the case and this is supposed to be fixed in the 2005
docs. Yes it can spawn a thread of each file but it is not limited to a
single thread per file. Even with a single file it is possible to spawn
multiple threads to read the same file. Here is what looks like a very
interesting article on IO in 2000. I haven't had a chance to read it yet
(hope to in the next few days) but it looks very promising.
http://www.microsoft.com/technet/pro...lIObasics.mspx
Andrew J. Kelly SQL MVP
"Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
news:u8xc256BFHA.1564@.TK2MSFTNGP09.phx.gbl...
>I just read that SS2K SE spawns Read Ahead requests in 4xExtents, 128 KB
> chunks, and spawns a thread per data file in each Filegroup. It also
> mentioned that EE can exceed the number of concurrent extents per request
> and managed the thread spawning more efficiently. But, damn if I can't
> remember where I came across the information.
> Anthony Thomas
>
> --
> "Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
> news:uNjLEV5BFHA.2180@.TK2MSFTNGP10.phx.gbl...
> An I agree with your comments except for the last one:
> Furthermore, more files per Filegroup will spawn
> additional disk threads per request.
> <<
> That was true with 7.0 but is not necessarily true with SQL2000. In 2000
> Sql Server can spawn multiple threads to read a single file as well. So
> just having multiple files does not mean it will be more effecient or
> spawn
> more threads than a single file.
>
> --
> Andrew J. Kelly SQL MVP
>
> "Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
> news:ep16rw1BFHA.3592@.TK2MSFTNGP09.phx.gbl...
>
|||Well, that doc confirmed at least part of what I read previously:
"SQL Server limits a single read-ahead request depth to 128 pages on most
editions. However, Microsoft SQL Server Enterprise Edition raises the limit
to 1,024 pages."
Sincerely,
Anthony Thomas

"Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
news:OIoyclBCFHA.3588@.TK2MSFTNGP11.phx.gbl...
As always, thanks Andrew. Yes, I am well aware of having to "filter" read
information and make judgement calls on the sources reliability. The
article I read seemed respectable, though. If I come across it, I'll post a
"What's up" response.
Sincerely,
Anthony Thomas

"Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
news:ewn3Iz7BFHA.2260@.TK2MSFTNGP14.phx.gbl...
Not sure which document that came from either. The read ahead is actually
dynamic in the size of each read ahead request based somewhat on how
fragmented the data is. It can be 8K or 128K, it just depends on if it is
possible to do so or not. Most of the documentation for 2000 is wrong in
that it may state you need multiple files to spawn multiple threads. That
is definitely not the case and this is supposed to be fixed in the 2005
docs. Yes it can spawn a thread of each file but it is not limited to a
single thread per file. Even with a single file it is possible to spawn
multiple threads to read the same file. Here is what looks like a very
interesting article on IO in 2000. I haven't had a chance to read it yet
(hope to in the next few days) but it looks very promising.
http://www.microsoft.com/technet/pro...lIObasics.mspx
Andrew J. Kelly SQL MVP
"Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
news:u8xc256BFHA.1564@.TK2MSFTNGP09.phx.gbl...
>I just read that SS2K SE spawns Read Ahead requests in 4xExtents, 128 KB
> chunks, and spawns a thread per data file in each Filegroup. It also
> mentioned that EE can exceed the number of concurrent extents per request
> and managed the thread spawning more efficiently. But, damn if I can't
> remember where I came across the information.
> Anthony Thomas
>
> --
> "Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
> news:uNjLEV5BFHA.2180@.TK2MSFTNGP10.phx.gbl...
> An I agree with your comments except for the last one:
> Furthermore, more files per Filegroup will spawn
> additional disk threads per request.
> <<
> That was true with 7.0 but is not necessarily true with SQL2000. In 2000
> Sql Server can spawn multiple threads to read a single file as well. So
> just having multiple files does not mean it will be more effecient or
> spawn
> more threads than a single file.
>
> --
> Andrew J. Kelly SQL MVP
>
> "Anthony Thomas" <ALThomas@.kc.rr.com> wrote in message
> news:ep16rw1BFHA.3592@.TK2MSFTNGP09.phx.gbl...
>