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AVG DISK QUEUE LENGTH is very high when run sys.dm_db_index_physic
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Iter
Dec 13, 2009, 8:36:01 PM12/13/09
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Hi Guys,
I have question regarding AVG DISK QUEUE LENGTH that is very high and was
almost 400-600 when run select from sys.dm_db_index_physical_stats view to
get fragmentation info my DBs. I have known that AVG DISK QUEUE LENGTH should
be below 2. But why it was hundreds? Can someone let me know why? Thanks in
advance.
I have question regarding AVG DISK QUEUE LENGTH that is very high and was
almost 400-600 when run select from sys.dm_db_index_physical_stats view to
get fragmentation info my DBs. I have known that AVG DISK QUEUE LENGTH should
be below 2. But why it was hundreds? Can someone let me know why? Thanks in
advance.
Uri Dimant
Dec 14, 2009, 4:20:09 AM12/14/09
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Iter
I ran it n SQL Server 2005 and do not see that column, am I missing
something?
I ran it n SQL Server 2005 and do not see that column, am I missing
something?
"Iter" <It...@discussions.microsoft.com> wrote in message
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Andrew J. Kelly
Dec 14, 2009, 8:21:04 AM12/14/09
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getting the physical stats for an index is I/O intensive and you most likely
have to read it from disk. So I would expect high disk Q lengths during this
operation. But it depends on the hardware configuration and how large the
index is as to how much physical I/O gets affected. If it is that high for
extended periods of time you probably could use more disks in your array.
have to read it from disk. So I would expect high disk Q lengths during this
operation. But it depends on the hardware configuration and how large the
index is as to how much physical I/O gets affected. If it is that high for
extended periods of time you probably could use more disks in your array.
--
Andrew J. Kelly SQL MVP
Solid Quality Mentors
"Iter" <It...@discussions.microsoft.com> wrote in message
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Iter
Dec 14, 2009, 10:06:01 AM12/14/09
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Hi Uri,
Phisical disk: AVG DISK QUEUE LENGTH is counter in the performance monitor.
I got very high, such as 400 or 500 when I ran select * from
sys.dm_db_index_physical_stats().
Phisical disk: AVG DISK QUEUE LENGTH is counter in the performance monitor.
I got very high, such as 400 or 500 when I ran select * from
sys.dm_db_index_physical_stats().
Andrew,
It went back to normal bellow 2 when that statement finished. But it was
extremely high, and execution time for that statement took longer, such as 25
minutes for 70G db and 200 tabkes. so I am fraid it had IO issue.
Thanks.
"Andrew J. Kelly" wrote:
> .
>
Uri Dimant
Dec 15, 2009, 8:17:04 AM12/15/09
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Ah I see, I hoped you specified a database/table/index scope when you ran
this dmv because it is pretty costly
this dmv because it is pretty costly
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