RAID and Transaction Logs Involved in Replication

I began documenting recommended RAID configurations for our environment. Typically I encourage using RAID 1 for T-Logs since log writes are sequential. But then I started to wonder about how replication impacts T-Logs. According to BOL:

"The Log Reader Agent monitors the transaction log of each database configured for transactional replication and copies the transactions marked for replication from the transaction log into the distribution database."

This being the case, doesn't that indicate the disk spindles will be repositioned when the Log Reader Agent reads the logs and copies the data to the Distribution database? If so, is RAID 1 still the best option?

Please let me know your thoughts.

Thanks, DaveThe impact of whatever RAID you use is very little as far as the efficency of transaction log, as long as you keep it simple and small enough. In a replication environment, transaction logs will not get dumped until the Log Reader loads the marked transactions onto the Distribution database. When you have large numbers of IOs, like over 35 millions commands within 5 hours, in our company. The Log Reader works extremely well in RAID 5. But the bottleneck is in Distribution database because all transactions get in there in a big hurry and cannot be distributed fast enough.

Wish this helps! Good luck.|||Someone in another forum pointed out that typically the Log Reader runs continuously. As a result the impact on the disk spindles should be small since only a couple of data pages are involved in the I/O. The only potential issue I see is when "Sync with Backup" is turned on. When on, the Log Reader Agent only sends T-Log data to the distribution database after a T-Log backup has been performed. In our environment this occurs every two hours. Depending upon the amount of transactions being processed, this has the potential to impact performance during the time the Log Reader is copying data from the T-Log and inserting it into the Distribution database. I suspect in most environments having the Log on a RAID 1, where the database is involved in replication, would not noticeably impact performance.

Thanks, Dave

Raid 10 and SQL

Are there any significant performance issues between running raid 5 verses
raid 10
with equal hardware configurations?. Thanks for being there to help, you
people have been life-savers.
Hi
Check out SQL Server 2000 Performance Tuning Technical Reference ISBN
0-7356-1270-6
There is a performance gain from Raid 10, this has to be taken into the
context of the system as a whole and what loads it will be under.
John
"coenzyme" wrote:

> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>
|||Yes for sure..
Only think i can say that cost is high with RAID 10 but for performance it's
great..
"coenzyme" wrote:

> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>
|||in most cases, yes.
I think I have read articles that suggest anything over 10% Writes you
should get off of RAID 5
Greg Jackson
PDX, Oregon
|||We found that RAID10 was over twice as fast when used for our database dump
volume as compared to RAID5. Not to mention that RAID10 is significantly
more tolerant of disk failures.
Mike Kruchten
"coenzyme" <coenzyme@.discussions.microsoft.com> wrote in message
news:74B28604-FE4A-4553-B134-269A3E6FBD1F@.microsoft.com...
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>
|||Check out what this site has to say about Raid 5:
http://www.baarf.com/
Andrew J. Kelly SQL MVP
"coenzyme" <coenzyme@.discussions.microsoft.com> wrote in message
news:74B28604-FE4A-4553-B134-269A3E6FBD1F@.microsoft.com...
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>

Raid 10 and SQL

Are there any significant performance issues between running raid 5 verses
raid 10
with equal hardware configurations?. Thanks for being there to help, you
people have been life-savers.Yes for sure..
Only think i can say that cost is high with RAID 10 but for performance it's
great..
"coenzyme" wrote:
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>|||Hi
Check out SQL Server 2000 Performance Tuning Technical Reference ISBN
0-7356-1270-6
There is a performance gain from Raid 10, this has to be taken into the
context of the system as a whole and what loads it will be under.
John
"coenzyme" wrote:
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>|||in most cases, yes.
I think I have read articles that suggest anything over 10% Writes you
should get off of RAID 5
Greg Jackson
PDX, Oregon|||We found that RAID10 was over twice as fast when used for our database dump
volume as compared to RAID5. Not to mention that RAID10 is significantly
more tolerant of disk failures.
Mike Kruchten
"coenzyme" <coenzyme@.discussions.microsoft.com> wrote in message
news:74B28604-FE4A-4553-B134-269A3E6FBD1F@.microsoft.com...
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>|||Check out what this site has to say about Raid 5:
http://www.baarf.com/
--
Andrew J. Kelly SQL MVP
"coenzyme" <coenzyme@.discussions.microsoft.com> wrote in message
news:74B28604-FE4A-4553-B134-269A3E6FBD1F@.microsoft.com...
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>

Raid 10 and SQL

Are there any significant performance issues between running raid 5 verses
raid 10
with equal hardware configurations?. Thanks for being there to help, you
people have been life-savers.Hi
Check out SQL Server 2000 Performance Tuning Technical Reference ISBN
0-7356-1270-6
There is a performance gain from Raid 10, this has to be taken into the
context of the system as a whole and what loads it will be under.
John
"coenzyme" wrote:

> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>|||Yes for sure..
Only think i can say that cost is high with RAID 10 but for performance it's
great..
"coenzyme" wrote:

> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>|||in most cases, yes.
I think I have read articles that suggest anything over 10% Writes you
should get off of RAID 5
Greg Jackson
PDX, Oregon|||We found that RAID10 was over twice as fast when used for our database dump
volume as compared to RAID5. Not to mention that RAID10 is significantly
more tolerant of disk failures.
Mike Kruchten
"coenzyme" <coenzyme@.discussions.microsoft.com> wrote in message
news:74B28604-FE4A-4553-B134-269A3E6FBD1F@.microsoft.com...
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>|||Check out what this site has to say about Raid 5:
http://www.baarf.com/
Andrew J. Kelly SQL MVP
"coenzyme" <coenzyme@.discussions.microsoft.com> wrote in message
news:74B28604-FE4A-4553-B134-269A3E6FBD1F@.microsoft.com...
> Are there any significant performance issues between running raid 5 verses
> raid 10
> with equal hardware configurations?. Thanks for being there to help, you
> people have been life-savers.
>

Raid 1+0 Configuration (0+1?)

I'm a relative newcomer to harddisk configurations, so bear with me. I
just have some questions about the way Raid 1+0 works. It's a
possibility that what I really want is Raid 0+1, but we'll figure that
out.
The way I understand that Raid 1+0 works is that you can have several
Raid 1 pairs joined together in a Raid 0 array. It looks like this:
Disk Disk Disk Disk
| | | |
R1 - R0 - R1 - R0 - R1 - R0 - R1
| | | |
Disk Disk Disk Disk
I have a few questions about this. The first question I have is: What
does this look like to Windows? I'm hoping that it appears as one
large volume that I can partition as I please. What I'd really like is
a logical configuration of 3 drives using the 4 disks: 1 drive for the
OS, 1 drive for the log files, and 1 drive for the data files. The
data drive would use 2 disks. Something like this:
C: D: E:
| |--| |
Disk Disk Disk Disk
| | | |
R1 - R0 - R1 - R0 - R1 - R0 - R1
| | | |
Disk Disk Disk Disk
Is this do-able from a Raid 1+0 configuration? Or do I need a Raid 0+1
configuration like this:
C: D: E:
| |--| |
Disk - R0 - Disk - R0 - Disk - R0 - Disk
|--|--|
R1
|--|--|
Disk - R0 - Disk - R0 - Disk - R0 - Disk
Also, what happens when a drive fails in the 1+0 array? Do reads and
writes still continue with the redundant drive, so that everything is
transparent to the user? When the drive is replaced, is there a huge
performance hit when the drive is being rebuilt?
Thanks in advance for all replies!
-Etan
Keep in mind that if you have one large RAID array it will remain one large
raid array to Windows. You do not receive any benefit in partitioning the
one large array (other than the logical breakdown of where things are).
If you had one RAID array that you could use for the OS
and one RAID array that you could use for tempdb
and one RAID array that that you could use for the data files
and one RAID array that you could use for the log files
You might get better performance over one large raid array because the
different controllers and disks within each array could be doing different
things at the same time.
Keith
"Etan" <aaawalrus@.yahoo.com> wrote in message
news:1106070523.937785.276140@.z14g2000cwz.googlegr oups.com...
> I'm a relative newcomer to harddisk configurations, so bear with me. I
> just have some questions about the way Raid 1+0 works. It's a
> possibility that what I really want is Raid 0+1, but we'll figure that
> out.
> The way I understand that Raid 1+0 works is that you can have several
> Raid 1 pairs joined together in a Raid 0 array. It looks like this:
> Disk Disk Disk Disk
> | | | |
> R1 - R0 - R1 - R0 - R1 - R0 - R1
> | | | |
> Disk Disk Disk Disk
> I have a few questions about this. The first question I have is: What
> does this look like to Windows? I'm hoping that it appears as one
> large volume that I can partition as I please. What I'd really like is
> a logical configuration of 3 drives using the 4 disks: 1 drive for the
> OS, 1 drive for the log files, and 1 drive for the data files. The
> data drive would use 2 disks. Something like this:
> C: D: E:
> | |--| |
> Disk Disk Disk Disk
> | | | |
> R1 - R0 - R1 - R0 - R1 - R0 - R1
> | | | |
> Disk Disk Disk Disk
>
> Is this do-able from a Raid 1+0 configuration? Or do I need a Raid 0+1
> configuration like this:
> C: D: E:
> | |--| |
> Disk - R0 - Disk - R0 - Disk - R0 - Disk
> |--|--|
> R1
> |--|--|
> Disk - R0 - Disk - R0 - Disk - R0 - Disk
>
> Also, what happens when a drive fails in the 1+0 array? Do reads and
> writes still continue with the redundant drive, so that everything is
> transparent to the user? When the drive is replaced, is there a huge
> performance hit when the drive is being rebuilt?
> Thanks in advance for all replies!
> -Etan
>
|||I agree with Keith in that there is little to no benefit to having multiple
logical drives aon a single drive array. You can accomplish the same thing
by simply placing each of those type files in their own folder. If you
partition the array 3 ways you run the risk of running out of space on
logical drive and having too much on another. There is no performance
benefit to doing what you stated and it gives the false impression that the
files may be on different physical drives.
Andrew J. Kelly SQL MVP
"Keith Kratochvil" <sqlguy.back2u@.comcast.net> wrote in message
news:OKxHv5Y$EHA.2552@.TK2MSFTNGP09.phx.gbl...
> Keep in mind that if you have one large RAID array it will remain one
> large
> raid array to Windows. You do not receive any benefit in partitioning the
> one large array (other than the logical breakdown of where things are).
> If you had one RAID array that you could use for the OS
> and one RAID array that you could use for tempdb
> and one RAID array that that you could use for the data files
> and one RAID array that you could use for the log files
> You might get better performance over one large raid array because the
> different controllers and disks within each array could be doing different
> things at the same time.
> --
> Keith
>
> "Etan" <aaawalrus@.yahoo.com> wrote in message
> news:1106070523.937785.276140@.z14g2000cwz.googlegr oups.com...
>
sql

Raid 1+0 Configuration (0+1?)

I'm a relative newcomer to harddisk configurations, so bear with me. I
just have some questions about the way Raid 1+0 works. It's a
possibility that what I really want is Raid 0+1, but we'll figure that
out.
The way I understand that Raid 1+0 works is that you can have several
Raid 1 pairs joined together in a Raid 0 array. It looks like this:
Disk Disk Disk Disk
| | | |
R1 - R0 - R1 - R0 - R1 - R0 - R1
| | | |
Disk Disk Disk Disk
I have a few questions about this. The first question I have is: What
does this look like to Windows? I'm hoping that it appears as one
large volume that I can partition as I please. What I'd really like is
a logical configuration of 3 drives using the 4 disks: 1 drive for the
OS, 1 drive for the log files, and 1 drive for the data files. The
data drive would use 2 disks. Something like this:
C: D: E:
| |--| |
Disk Disk Disk Disk
| | | |
R1 - R0 - R1 - R0 - R1 - R0 - R1
| | | |
Disk Disk Disk Disk
Is this do-able from a Raid 1+0 configuration? Or do I need a Raid 0+1
configuration like this:
C: D: E:
| |--| |
Disk - R0 - Disk - R0 - Disk - R0 - Disk
|--|--|
R1
|--|--|
Disk - R0 - Disk - R0 - Disk - R0 - Disk
Also, what happens when a drive fails in the 1+0 array? Do reads and
writes still continue with the redundant drive, so that everything is
transparent to the user? When the drive is replaced, is there a huge
performance hit when the drive is being rebuilt?
Thanks in advance for all replies!
-EtanKeep in mind that if you have one large RAID array it will remain one large
raid array to Windows. You do not receive any benefit in partitioning the
one large array (other than the logical breakdown of where things are).
If you had one RAID array that you could use for the OS
and one RAID array that you could use for tempdb
and one RAID array that that you could use for the data files
and one RAID array that you could use for the log files
You might get better performance over one large raid array because the
different controllers and disks within each array could be doing different
things at the same time.
Keith
"Etan" <aaawalrus@.yahoo.com> wrote in message
news:1106070523.937785.276140@.z14g2000cwz.googlegroups.com...
> I'm a relative newcomer to harddisk configurations, so bear with me. I
> just have some questions about the way Raid 1+0 works. It's a
> possibility that what I really want is Raid 0+1, but we'll figure that
> out.
> The way I understand that Raid 1+0 works is that you can have several
> Raid 1 pairs joined together in a Raid 0 array. It looks like this:
> Disk Disk Disk Disk
> | | | |
> R1 - R0 - R1 - R0 - R1 - R0 - R1
> | | | |
> Disk Disk Disk Disk
> I have a few questions about this. The first question I have is: What
> does this look like to Windows? I'm hoping that it appears as one
> large volume that I can partition as I please. What I'd really like is
> a logical configuration of 3 drives using the 4 disks: 1 drive for the
> OS, 1 drive for the log files, and 1 drive for the data files. The
> data drive would use 2 disks. Something like this:
> C: D: E:
> | |--| |
> Disk Disk Disk Disk
> | | | |
> R1 - R0 - R1 - R0 - R1 - R0 - R1
> | | | |
> Disk Disk Disk Disk
>
> Is this do-able from a Raid 1+0 configuration? Or do I need a Raid 0+1
> configuration like this:
> C: D: E:
> | |--| |
> Disk - R0 - Disk - R0 - Disk - R0 - Disk
> |--|--|
> R1
> |--|--|
> Disk - R0 - Disk - R0 - Disk - R0 - Disk
>
> Also, what happens when a drive fails in the 1+0 array? Do reads and
> writes still continue with the redundant drive, so that everything is
> transparent to the user? When the drive is replaced, is there a huge
> performance hit when the drive is being rebuilt?
> Thanks in advance for all replies!
> -Etan
>|||I agree with Keith in that there is little to no benefit to having multiple
logical drives aon a single drive array. You can accomplish the same thing
by simply placing each of those type files in their own folder. If you
partition the array 3 ways you run the risk of running out of space on
logical drive and having too much on another. There is no performance
benefit to doing what you stated and it gives the false impression that the
files may be on different physical drives.
Andrew J. Kelly SQL MVP
"Keith Kratochvil" <sqlguy.back2u@.comcast.net> wrote in message
news:OKxHv5Y$EHA.2552@.TK2MSFTNGP09.phx.gbl...
> Keep in mind that if you have one large RAID array it will remain one
> large
> raid array to Windows. You do not receive any benefit in partitioning the
> one large array (other than the logical breakdown of where things are).
> If you had one RAID array that you could use for the OS
> and one RAID array that you could use for tempdb
> and one RAID array that that you could use for the data files
> and one RAID array that you could use for the log files
> You might get better performance over one large raid array because the
> different controllers and disks within each array could be doing different
> things at the same time.
> --
> Keith
>
> "Etan" <aaawalrus@.yahoo.com> wrote in message
> news:1106070523.937785.276140@.z14g2000cwz.googlegroups.com...
>

Raid 1+0 Configuration (0+1?)

I'm a relative newcomer to harddisk configurations, so bear with me. I
just have some questions about the way Raid 1+0 works. It's a
possibility that what I really want is Raid 0+1, but we'll figure that
out.
The way I understand that Raid 1+0 works is that you can have several
Raid 1 pairs joined together in a Raid 0 array. It looks like this:
Disk Disk Disk Disk
| | | |
R1 - R0 - R1 - R0 - R1 - R0 - R1
| | | |
Disk Disk Disk Disk
I have a few questions about this. The first question I have is: What
does this look like to Windows? I'm hoping that it appears as one
large volume that I can partition as I please. What I'd really like is
a logical configuration of 3 drives using the 4 disks: 1 drive for the
OS, 1 drive for the log files, and 1 drive for the data files. The
data drive would use 2 disks. Something like this:
C: D: E:
| |--| |
Disk Disk Disk Disk
| | | |
R1 - R0 - R1 - R0 - R1 - R0 - R1
| | | |
Disk Disk Disk Disk
Is this do-able from a Raid 1+0 configuration? Or do I need a Raid 0+1
configuration like this:
C: D: E:
| |--| |
Disk - R0 - Disk - R0 - Disk - R0 - Disk
|--|--|
R1
|--|--|
Disk - R0 - Disk - R0 - Disk - R0 - Disk
Also, what happens when a drive fails in the 1+0 array? Do reads and
writes still continue with the redundant drive, so that everything is
transparent to the user? When the drive is replaced, is there a huge
performance hit when the drive is being rebuilt?
Thanks in advance for all replies!
-EtanKeep in mind that if you have one large RAID array it will remain one large
raid array to Windows. You do not receive any benefit in partitioning the
one large array (other than the logical breakdown of where things are).
If you had one RAID array that you could use for the OS
and one RAID array that you could use for tempdb
and one RAID array that that you could use for the data files
and one RAID array that you could use for the log files
You might get better performance over one large raid array because the
different controllers and disks within each array could be doing different
things at the same time.
--
Keith
"Etan" <aaawalrus@.yahoo.com> wrote in message
news:1106070523.937785.276140@.z14g2000cwz.googlegroups.com...
> I'm a relative newcomer to harddisk configurations, so bear with me. I
> just have some questions about the way Raid 1+0 works. It's a
> possibility that what I really want is Raid 0+1, but we'll figure that
> out.
> The way I understand that Raid 1+0 works is that you can have several
> Raid 1 pairs joined together in a Raid 0 array. It looks like this:
> Disk Disk Disk Disk
> | | | |
> R1 - R0 - R1 - R0 - R1 - R0 - R1
> | | | |
> Disk Disk Disk Disk
> I have a few questions about this. The first question I have is: What
> does this look like to Windows? I'm hoping that it appears as one
> large volume that I can partition as I please. What I'd really like is
> a logical configuration of 3 drives using the 4 disks: 1 drive for the
> OS, 1 drive for the log files, and 1 drive for the data files. The
> data drive would use 2 disks. Something like this:
> C: D: E:
> | |--| |
> Disk Disk Disk Disk
> | | | |
> R1 - R0 - R1 - R0 - R1 - R0 - R1
> | | | |
> Disk Disk Disk Disk
>
> Is this do-able from a Raid 1+0 configuration? Or do I need a Raid 0+1
> configuration like this:
> C: D: E:
> | |--| |
> Disk - R0 - Disk - R0 - Disk - R0 - Disk
> |--|--|
> R1
> |--|--|
> Disk - R0 - Disk - R0 - Disk - R0 - Disk
>
> Also, what happens when a drive fails in the 1+0 array? Do reads and
> writes still continue with the redundant drive, so that everything is
> transparent to the user? When the drive is replaced, is there a huge
> performance hit when the drive is being rebuilt?
> Thanks in advance for all replies!
> -Etan
>|||I agree with Keith in that there is little to no benefit to having multiple
logical drives aon a single drive array. You can accomplish the same thing
by simply placing each of those type files in their own folder. If you
partition the array 3 ways you run the risk of running out of space on
logical drive and having too much on another. There is no performance
benefit to doing what you stated and it gives the false impression that the
files may be on different physical drives.
--
Andrew J. Kelly SQL MVP
"Keith Kratochvil" <sqlguy.back2u@.comcast.net> wrote in message
news:OKxHv5Y$EHA.2552@.TK2MSFTNGP09.phx.gbl...
> Keep in mind that if you have one large RAID array it will remain one
> large
> raid array to Windows. You do not receive any benefit in partitioning the
> one large array (other than the logical breakdown of where things are).
> If you had one RAID array that you could use for the OS
> and one RAID array that you could use for tempdb
> and one RAID array that that you could use for the data files
> and one RAID array that you could use for the log files
> You might get better performance over one large raid array because the
> different controllers and disks within each array could be doing different
> things at the same time.
> --
> Keith
>
> "Etan" <aaawalrus@.yahoo.com> wrote in message
> news:1106070523.937785.276140@.z14g2000cwz.googlegroups.com...
>> I'm a relative newcomer to harddisk configurations, so bear with me. I
>> just have some questions about the way Raid 1+0 works. It's a
>> possibility that what I really want is Raid 0+1, but we'll figure that
>> out.
>> The way I understand that Raid 1+0 works is that you can have several
>> Raid 1 pairs joined together in a Raid 0 array. It looks like this:
>> Disk Disk Disk Disk
>> | | | |
>> R1 - R0 - R1 - R0 - R1 - R0 - R1
>> | | | |
>> Disk Disk Disk Disk
>> I have a few questions about this. The first question I have is: What
>> does this look like to Windows? I'm hoping that it appears as one
>> large volume that I can partition as I please. What I'd really like is
>> a logical configuration of 3 drives using the 4 disks: 1 drive for the
>> OS, 1 drive for the log files, and 1 drive for the data files. The
>> data drive would use 2 disks. Something like this:
>> C: D: E:
>> | |--| |
>> Disk Disk Disk Disk
>> | | | |
>> R1 - R0 - R1 - R0 - R1 - R0 - R1
>> | | | |
>> Disk Disk Disk Disk
>>
>> Is this do-able from a Raid 1+0 configuration? Or do I need a Raid 0+1
>> configuration like this:
>> C: D: E:
>> | |--| |
>> Disk - R0 - Disk - R0 - Disk - R0 - Disk
>> |--|--|
>> R1
>> |--|--|
>> Disk - R0 - Disk - R0 - Disk - R0 - Disk
>>
>> Also, what happens when a drive fails in the 1+0 array? Do reads and
>> writes still continue with the redundant drive, so that everything is
>> transparent to the user? When the drive is replaced, is there a huge
>> performance hit when the drive is being rebuilt?
>> Thanks in advance for all replies!
>> -Etan
>