weird memory usage on sql server

  • Hi Folks,

    I got this weird issue on sql server.

    I am running window 2008 r2 enterprise 64 bit with 8 gb of ram and running SQL Server 2008 10.0.4000 64 bit standard edition. The maxium server memory is set at 5 gbs. When I look at task manager the sql server process's working set barely gets anymore than this setting. This is a dedicated sql machine.

    Anyway occasionally the avialable memory on the machine gets below 200mb (97% usage). I am unsure why as the sql process working set has barely changed, at the low memory time. The rest of the processes in task manager shown would not make up more the 100-200 mbs. I am guessing it has something to do with the o.s. but using more than 2.5gb for the o.s. seems not right to me.

    I did a sql trace and looked at the logical reads. If the problem was caused by a particular query I would have thought that, when the query was finished the memory would be relieved. What I seem to be seeing is Memory does get relieved (back to about 1-1.5 gb avialable memory) but the trace shows no queries that has been run for the duration of the low memory period and also the queries do not show massive logical reads at the time the memory is relieved.

    Hope I make sense - please help!

  • Don't use Task Manager to check SQL's memory. It can be completely wrong.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • The issue is related to SQL SERVER Performance issue for sure

    Increasing memory is one of the best ways to improve SQL Server performance

    because more data can be cached in memory.

    You can check you memory usage by using storage management for SQL related tools also

  • djordan 4543 (12/18/2012)


    Hi Folks,

    I got this weird issue on sql server.

    I am running window 2008 r2 enterprise 64 bit with 8 gb of ram and running SQL Server 2008 10.0.4000 64 bit standard edition. The maxium server memory is set at 5 gbs. When I look at task manager the sql server process's working set barely gets anymore than this setting. This is a dedicated sql machine.

    Anyway occasionally the avialable memory on the machine gets below 200mb (97% usage). I am unsure why as the sql process working set has barely changed, at the low memory time. The rest of the processes in task manager shown would not make up more the 100-200 mbs. I am guessing it has something to do with the o.s. but using more than 2.5gb for the o.s. seems not right to me.

    I did a sql trace and looked at the logical reads. If the problem was caused by a particular query I would have thought that, when the query was finished the memory would be relieved. What I seem to be seeing is Memory does get relieved (back to about 1-1.5 gb avialable memory) but the trace shows no queries that has been run for the duration of the low memory period and also the queries do not show massive logical reads at the time the memory is relieved.

    Hope I make sense - please help!

    Hi,

    As a matter of interest, do you have SCOM monitoring your server? Also, has an anti-virus package been deployed on this server?

    Anna

  • You need to check anti-virus software or get the server guys involved if this is a VM

    Regards

  • thanks guys,

    would perfmon be betterfor checking this?

    SCOM is not monitoring this server (wish it was)

    Symantec endpoint protection is our av program there is a full scan every monday morning at 5am.

  • I have just been monitoring the all processes working set in performance monitor for a few hours. There has been a couple of times where memory has been upto 97% utilization but the working set memory does not seem to be budging.

    Is there anything else I can do to diagnose this?

  • Have you checked the "non buffer pool" memory how much being uhsed there ?

    -------Bhuvnesh----------
    I work only to learn Sql Server...though my company pays me for getting their stuff done;-)

  • thanks - I think I might be getting closer.. how do I check that?

  • djordan 4543 (12/18/2012)


    thanks - I think I might be getting closer.. how do I check that?

    --Bpool stats

    select (bpool_committed * 8192)/ (1024*1024) as bpool_committed_mb

    , (cast(bpool_commit_target as bigint) * 8192) / (1024*1024) as bpool_target_mb,

    (bpool_visible * 8192) / (1024*1024) as bpool_visible_mb

    from sys.dm_os_sys_info

    go

    -- Get me physical RAM installed

    -- and size of user VAS

    select physical_memory_in_bytes/(1024*1024) as phys_mem_mb,

    virtual_memory_in_bytes/(1024*1024) as user_virtual_address_space_size

    from sys.dm_os_sys_info

    go

    --

    -- Get me other information about system memory

    --

    select total_physical_memory_kb/(1024) as phys_mem_mb,

    available_physical_memory_kb/(1024) as avail_phys_mem_mb,

    system_cache_kb/(1024) as sys_cache_mb,

    (kernel_paged_pool_kb+kernel_nonpaged_pool_kb)/(1024) as kernel_pool_mb,

    total_page_file_kb/(1024) as total_virtual_memory_mb,

    available_page_file_kb/(1024) as available_virtual_memory_mb,

    system_memory_state_desc

    from sys.dm_os_sys_memory

    go

    -- Get me memory information about SQLSERVR.EXE process

    -- GetMemoryProcessInfo() API used for this

    -- physical_memory_in_use_kb

    select physical_memory_in_use_kb/(1024) as sql_physmem_inuse_mb,

    locked_page_allocations_kb/(1024) as awe_memory_mb,

    total_virtual_address_space_kb/(1024) as max_vas_mb,

    virtual_address_space_committed_kb/(1024) as sql_committed_mb,

    memory_utilization_percentage as working_set_percentage,

    virtual_address_space_available_kb/(1024) as vas_available_mb,

    process_physical_memory_low as is_there_external_pressure,

    process_virtual_memory_low as is_there_vas_pressure

    from sys.dm_os_process_memory

    go

    select * from sys.dm_os_ring_buffers

    where ring_buffer_type like 'RING_BUFFER_RESOURCE%'

    go

    select memory_node_id as node, virtual_address_space_reserved_kb/(1024) as VAS_reserved_mb,

    virtual_address_space_committed_kb/(1024) as virtual_committed_mb,

    locked_page_allocations_kb/(1024) as locked_pages_mb,

    single_pages_kb/(1024) as single_pages_mb,

    multi_pages_kb/(1024) as multi_pages_mb,

    shared_memory_committed_kb/(1024) as shared_memory_mb

    from sys.dm_os_memory_nodes

    where memory_node_id != 64

    go

    with vasummary(Size,reserved,free) as ( select size = vadump.size,

    reserved = SUM(case(convert(int, vadump.base) ^ 0) when 0 then 0 else 1 end),

    free = SUM(case(convert(int, vadump.base) ^ 0x0) when 0 then 1 else 0 end)

    from

    (select CONVERT(varbinary, sum(region_size_in_bytes)) as size,

    region_allocation_base_address as base

    from sys.dm_os_virtual_address_dump

    where region_allocation_base_address <> 0x0

    group by region_allocation_base_address

    UNION(

    select CONVERT(varbinary, region_size_in_bytes),

    region_allocation_base_address

    from sys.dm_os_virtual_address_dump

    where region_allocation_base_address = 0x0)

    )

    as vadump

    group by size)

    select * from vasummary

    go

    -- Get me all clerks that take some memory

    --

    select * from sys.dm_os_memory_clerks

    where (single_pages_kb > 0) or (multi_pages_kb > 0)

    or (virtual_memory_committed_kb > 0)

    go

    -- Get me stolen pages

    --

    select (SUM(single_pages_kb)*1024)/8192 as total_stolen_pages

    from sys.dm_os_memory_clerks

    go

    -- Breakdown clerks with stolen pages

    select type, name, sum((single_pages_kb*1024)/8192) as stolen_pages

    from sys.dm_os_memory_clerks

    where single_pages_kb > 0

    group by type, name

    order by stolen_pages desc

    go

    -- Get me the total amount of memory consumed by multi_page consumers

    --

    select SUM(multi_pages_kb)/1024 as total_multi_pages_mb

    from sys.dm_os_memory_clerks

    go

    -- What about multi_page consumers

    --

    select type, name, sum(multi_pages_kb)/1024 as multi_pages_mb

    from sys.dm_os_memory_clerks

    where multi_pages_kb > 0

    group by type, name

    order by multi_pages_mb desc

    go

    -- Let's now get the total consumption of virtual allocator

    --

    select SUM(virtual_memory_committed_kb)/1024 as total_virtual_mem_mb

    from sys.dm_os_memory_clerks

    go

    -- Breakdown the clerks who use virtual allocator

    --

    select type, name, sum(virtual_memory_committed_kb)/1024 as virtual_mem_mb

    from sys.dm_os_memory_clerks

    where virtual_memory_committed_kb > 0

    group by type, name

    order by virtual_mem_mb desc

    go

    -- Is anyone using AWE allocator?

    --

    select SUM(awe_allocated_kb)/1024 as total_awe_allocated_mb

    from sys.dm_os_memory_clerks

    go

    -- Who is the AWE user?

    --

    select type, name, sum(awe_allocated_kb)/1024 as awe_allocated_mb

    from sys.dm_os_memory_clerks

    where awe_allocated_kb > 0

    group by type, name

    order by awe_allocated_mb desc

    go

    -- What is the total memory used by the clerks?

    --

    select (sum(multi_pages_kb)+

    SUM(virtual_memory_committed_kb)+

    SUM(awe_allocated_kb))/1024

    from sys.dm_os_memory_clerks

    go

    --

    -- Does this sync up with what the node thinks?

    --

    select SUM(virtual_address_space_committed_kb)/1024 as total_node_virtual_memory_mb,

    SUM(locked_page_allocations_kb)/1024 as total_awe_memory_mb,

    SUM(single_pages_kb)/1024 as total_single_pages_mb,

    SUM(multi_pages_kb)/1024 as total_multi_pages_mb

    from sys.dm_os_memory_nodes

    where memory_node_id != 64

    go

    --

    -- Total memory used by SQL Server through SQLOS memory nodes

    -- including DAC node

    -- What takes up the rest of the space?

    select (SUM(virtual_address_space_committed_kb)+

    SUM(locked_page_allocations_kb)+

    SUM(multi_pages_kb))/1024 as total_sql_memusage_mb

    from sys.dm_os_memory_nodes

    go

    --

    -- Who are the biggest cache stores?

    select name, type, (SUM(single_pages_kb)+SUM(multi_pages_kb))/1024

    as cache_size_mb

    from sys.dm_os_memory_cache_counters

    where type like 'CACHESTORE%'

    group by name, type

    order by cache_size_mb desc

    go

    --

    -- Who are the biggest user stores?

    select name, type, (SUM(single_pages_kb)+SUM(multi_pages_kb))/1024

    as cache_size_mb

    from sys.dm_os_memory_cache_counters

    where type like 'USERSTORE%'

    group by name, type

    order by cache_size_mb desc

    go

    --

    -- Who are the biggest object stores?

    select name, type, (SUM(single_pages_kb)+SUM(multi_pages_kb))/1024

    as cache_size_mb

    from sys.dm_os_memory_clerks

    where type like 'OBJECTSTORE%'

    group by name, type

    order by cache_size_mb desc

    go

    select mc.type, mo.type from sys.dm_os_memory_clerks mc

    join sys.dm_os_memory_objects mo

    on mc.page_allocator_address = mo.page_allocator_address

    group by mc.type, mo.type

    order by mc.type, mo.type

    go

    -------Bhuvnesh----------
    I work only to learn Sql Server...though my company pays me for getting their stuff done;-)

  • thanks - i'll c what I can do with that.

  • Just to reiterate here...

    GilaMonster (12/18/2012)


    Don't use Task Manager to check SQL's memory. It can be completely wrong.

    Use Perfmon with either the SQL Server memory counters and/or the process-specific counters.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • yep used perfmon memory.avialable_memory and process.workingset for all the processes - did not see anything useful from that.

    (i.e nothing spike in the working sets when avilable memory reduced dramatically).

    I thought I might setup some monitoring with those dmvs bhuvnesh sent through.. gonna try now!

    dj

  • with the script provided - is there anything in particular to look for . I ran the script during high memory usage and low memory usage and I don't see anything of any particular concern (I don't profess to understand everything the script is doing though).

    I thought perhap sql plans in the memory clerks may have been high (comparing values between high memory times and low memory times) but I appeared to be wrong here.

  • djordan 4543 (1/7/2013)


    with the script provided - is there anything in particular to look for . I ran the script during high memory usage and low memory usage and I don't see anything of any particular concern (I don't profess to understand everything the script is doing though).

    i qam sorry there is no straight forward bread for this. you need to see the result of each query carefully and before result see "the commented line above of every query"

    then you need to dig into the issues.

    Are you still seeing continous memory usage ( any particular time period or pattern)? have you seen the sql error log ? or even the system log ?

    Have you seen the tempdb usage ? do you have dedicated or separate disk for it ?

    and any kind of IO high usage ?

    see this link for memory http://blogs.msdn.com/b/karthick_pk/archive/2012/06/15/troubleshooting-sql-server-memory.aspx

    -------Bhuvnesh----------
    I work only to learn Sql Server...though my company pays me for getting their stuff done;-)

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