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01-04-2012 11:15 PM
01-04-2012 11:15 PM
How to disable the filesystem cache on HP-UX 11i V1
Hi,
We have got an reply from SAP to disable the filesystem cache on /sapdb/SID/sapdata1, /sapdb/SID/sapdata2 .... /sapdb/SID/sapdata10 file system. As system is doing quite a lot of memory swapping (paging).
Please let me know if swap utilization on system is high will have performance issues?
Thanks,
Narendra
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01-05-2012 03:32 AM
01-05-2012 03:32 AM
Re: How to disable the filesystem cache on HP-UX 11i V1
High swap utilsation is a factor impacting the performance. However detailed analysis is need to find actual exact cause of performance degradation..
Pls send the swapinfo output
#swapinfo -tam
Pradeep
I am an HP Employee
A quick resolution to technical issues for your HP Enterprise products is just a click away HP Support Center Knowledge-base
See Self Help Post for more details
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01-05-2012 10:13 PM
01-05-2012 10:13 PM
Re: How to disable the filesystem cache on HP-UX 11i V1
Hi Pradeep,
Please find the swapinfo output as below,
server07:[/]# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4096 912 3184 22% 0 - 1 /dev/vg00/lvol2
dev 4000 909 3091 23% 0 - 1 /dev/vg00/lvswap1
dev 8192 911 7281 11% 0 - 1 /dev/vgmaxfs/lvswap2
dev 8192 915 7277 11% 0 - 1 /dev/vgmaxfs/lvswap3
dev 4080 914 3166 22% 0 - 1 /dev/vgmaxfs/lvswap4
dev 8192 914 7278 11% 0 - 1 /dev/vgmaxfs/lvswap5
dev 8192 920 7272 11% 0 - 1 /dev/vgmaxfs/lvswap6
dev 8192 916 7276 11% 0 - 1 /dev/vgmaxfs/lvswap7
dev 8192 915 7277 11% 0 - 1 /dev/vgmaxfs/lvswap8
reserve - 29270 -29270
memory 25498 2878 22620 11%
total 86826 40374 46452 46% - 0 -
Thanks,
Narendra
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- swapinfo
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01-06-2012 01:00 AM
01-06-2012 01:00 AM
Re: How to disable the filesystem cache on HP-UX 11i V1
from the output, the swap usage is only 22% average.. If you still face any performance issue detailed analysis is need. I would recommend you to contact HP support for in depth analysis.
Pradeep
I am an HP Employee
A quick resolution to technical issues for your HP Enterprise products is just a click away HP Support Center Knowledge-base
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01-06-2012 08:34 AM - edited 01-06-2012 08:35 AM
01-06-2012 08:34 AM - edited 01-06-2012 08:35 AM
Re: How to disable the buffer cache on HP-UX 11.11?
>We have got an reply from SAP to disable the filesystem cache on /sapdb/SID/sapdata1 ...
You can only disable/reduce the buffer cache on the whole system.
What are the values of dbc_max_pct(5) & dbc_min_pct(5)?
>if swap utilization on system is high will have performance issues?
Doing paging is never a good thing. What does "vmstat 5 5" show? (And look at the "po" column.)
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01-06-2012 09:43 AM
01-06-2012 09:43 AM
Re: How to disable the filesystem cache on HP-UX 11i V1
> We have got an reply from SAP to disable the
> filesystem cache on /sapdb/SID/sapdata1,
> /sapdb/SID/sapdata2 .... /sapdb/SID/sapdata10
> file system. As system is doing quite a lot of memory
> swapping (paging).
Are you certain SAP wants all filesystem cache disabled on this system or just for these SAP filesystems? My guess is they're really suggesting you disable caching for the SAP filesystems, not the entire system. That would mean mounting these filesystems using either Direct I/O or Concurrent I/O. Both of those VxFS mount options would effectively bypass the filesystem cache just for those filesystems.
Can you confirm with SAP if they're recommending disabling all caching or are they suggesting you use Direct/Concurrent I/O for these SAP filesystems?
Dave
[Any personal opinions expressed are mine, and not official statements on behalf of Hewlett Packard Enterprise]
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01-09-2012 01:57 AM
01-09-2012 01:57 AM
Re: How to disable the buffer cache on HP-UX 11.11?
Hi Dennis,
Please find the values of dbc_max_pct & dbc_min_pct as below,
dbc_max_pct 8
dbc_min_pct 5
And also the output "vmstat 5 5" as below,
test07:[/]# vmstat 5 5
procs memory page faults cpu
r b w avm free re at pi po fr de sr in sy cs us sy id
16 1 0 8081789 176008 19 5 6 7 0 0 104 3622 36474 28244 30 18 52
16 1 0 8081789 175938 2 0 0 0 0 0 0 7554 97586 87950 38 53 9
20 1 0 8354691 175938 6 0 0 0 0 0 0 6519 110868 102216 21 69 10
20 1 0 8354691 175937 0 0 0 0 0 0 0 7116 107778 99496 33 57 10
16 5 0 7979738 175937 7 0 0 0 0 0 0 5571 118269 110818 23 73 4
Thanks,
Narendra
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01-09-2012 02:06 AM
01-09-2012 02:06 AM
Re: How to disable the filesystem cache on HP-UX 11i V1
Hi Dave,
SAP wants only SAP filesystems to bypass the filesystem cache. Please let me know how to bypass only the SAP filesystem cache for VxFS mounted filesystem. OS HP-UX 11i V1 (Base VERITAS Volume Manager Bundle 3.5 for HP-UX) with HP OnLineJFS 3.5 i.e. /sapdb/SID/sapdata1, /sapdb/SID/sapdata2 .... /sapdb/SID/sapdata10.
Please let me know what are advantage and dis-advantage of disabling the filesystem cache.
Thanks,
Narendra
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01-09-2012 03:59 AM
01-09-2012 03:59 AM
Re: How to disable the filesystem cache on HP-UX 11i V1
Hi Dave,
I checked an filesystem cache is disabled on the VxFS SAP filesystems as below;
server07:[/]# vxtunefs /dev/vgmaxdb/lvmaxdata1
Filesystem i/o parameters for /sapdb/SID/sapdata1
read_pref_io = 65536
read_nstream = 1
read_unit_io = 65536
write_pref_io = 65536
write_nstream = 1
write_unit_io = 65536
pref_strength = 10
buf_breakup_size = 131072
discovered_direct_iosz = 262144
max_direct_iosz = 1048576
default_indir_size = 8192
qio_cache_enable = 0
write_throttle = 0
max_diskq = 1048576
initial_extent_size = 1
max_seqio_extent_size = 2048
max_buf_data_size = 8192
hsm_write_prealloc = 0
read_ahead = 1
Please can you let me know how to enable the direct I/O on hp-ux VxFS filesystem? And also how to check if VxFS filesystem is already enabled for direct I/O?
Is this how we can enable the direct I/O for filesystem
- Use the following mount options in /etc/fstab: convosync=direct,mincache=direct,delaylog,nodatainlog
e.g.
/dev/vg01/lvol1 /test vxfs convosync=direct,mincache=direct,delaylog,nodatainlog 0 2
And also can I install the latest VxFS software i.e. VxFS 5.0.1 on HP-UX 11i V1 on PA-RISC server RP7400. Or any other VxFS version which supports Concurrent I/O (CIO). And also we have default VxFS (Base VERITAS Volume Manager Bundle 3.5 for HP-UX) with HP OnLineJFS 3.5). Do we have to purchase VERITAS VxFS other version than default which is available on HP-UX 11i V1 OS.
And also it looks like i can - For systems with >=40GB Memory set the buffercache/filecache to 1% of Physical Memory (since the cache is not used by direct I/O). e.g. dbc_max_pct=dbc_min_pct=1 (HP-UX 11.11/11.23) .
Thanks,
Narendra
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01-09-2012 12:57 PM
01-09-2012 12:57 PM
Re: How to disable the buffer cache on HP-UX 11.11?
>Please find the values of dbc_max_pct & dbc_min_pct as below,
>dbc_max_pct 8 dbc_min_pct 5
Your buffer cache seems small enough.
>And also the output "vmstat 5 5" as below,
procs memory page
r b w avm free re at pi po
16 1 0 8081789 176008 19 5 6 7
You have very few Page Outs, you aren't short on memory during this time period.