Wednesday, March 7, 2012

Memory problem related to DBCC CHECKDB

I have been monitoring my SQL server and noticing abrupt drops in Available
Memory -- happening about once a week.
I could not figure out what was causing this until I discovered that the low
memory condition corresponded to the exact time that I run a weekly DBCC CH
ECKDB command on a database.
Scenario:
1. Available Memory starts at about 1000MB (this is normal)
2. Run DBCC CHECKDB on a particular database (only occurs on this one).
3. Available Memory suddently drops to less than 200MB free!
4. The Memory is never freed up until I re-start SQL Server.
Has anyone ever seen this problem before?
Thanks,
DanIt is by Design.
SQL Server will not relinquish memory once allocated, unless there is a requ
est from the OS
--
HTH
Satish Balusa
Corillian Corp.
"Dan Carollo" <dan.carollo@.verizon.net> wrote in message news:uw$X%23mS5DHA.
2764@.TK2MSFTNGP09.phx.gbl...
I have been monitoring my SQL server and noticing abrupt drops in Available
Memory -- happening about once a week.
I could not figure out what was causing this until I discovered that the low
memory condition corresponded to the exact time that I run a weekly DBCC CH
ECKDB command on a database.
Scenario:
1. Available Memory starts at about 1000MB (this is normal)
2. Run DBCC CHECKDB on a particular database (only occurs on this one).
3. Available Memory suddently drops to less than 200MB free!
4. The Memory is never freed up until I re-start SQL Server.
Has anyone ever seen this problem before?
Thanks,
Dan|||Dan,
What is wrong with this?
If you still have available memory ... your performance is not hurting.
Most of this memory is most likely in buffer cache.
-Lars
"Dan Carollo" <dan.carollo@.verizon.net> wrote in message news:uw$X%23mS5DHA.
2764@.TK2MSFTNGP09.phx.gbl...
I have been monitoring my SQL server and noticing abrupt drops in Available
Memory -- happening about once a week.
I could not figure out what was causing this until I discovered that the low
memory condition corresponded to the exact time that I run a weekly DBCC CH
ECKDB command on a database.
Scenario:
1. Available Memory starts at about 1000MB (this is normal)
2. Run DBCC CHECKDB on a particular database (only occurs on this one).
3. Available Memory suddently drops to less than 200MB free!
4. The Memory is never freed up until I re-start SQL Server.
Has anyone ever seen this problem before?
Thanks,
Dan|||Further to what other replies have said, it is buffer pool memory. DBCC CHEC
KDB reads every allocated page in the database using parallel threads and si
gnificant readahead and so the buffer pool grows to accomodate this.
As long as you're not short of memory, there's no big deal.
--
Paul Randal
Dev Lead, Microsoft SQL Server Storage Engine
This posting is provided "AS IS" with no warranties, and confers no rights.
"Dan Carollo" <dan.carollo@.verizon.net> wrote in message news:uw$X#mS5DHA.27
64@.TK2MSFTNGP09.phx.gbl...
I have been monitoring my SQL server and noticing abrupt drops in Available
Memory -- happening about once a week.
I could not figure out what was causing this until I discovered that the low
memory condition corresponded to the exact time that I run a weekly DBCC CH
ECKDB command on a database.
Scenario:
1. Available Memory starts at about 1000MB (this is normal)
2. Run DBCC CHECKDB on a particular database (only occurs on this one).
3. Available Memory suddently drops to less than 200MB free!
4. The Memory is never freed up until I re-start SQL Server.
Has anyone ever seen this problem before?
Thanks,
Dan

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