RE: Prevent ASM from using any hugepages
- From: <Christopher.Taylor2@xxxxxxxxxxxx>
- To: <mwf@xxxxxxxx>, <Mark.Bobak@xxxxxxxxxxxx>
- Date: Fri, 17 May 2013 16:34:08 -0500
Interesting ideas all of them. Thankfully ASM didn't use many so I'm not going
to worry about it any more. It was just suprising based on what I had read,
and of course I'm greedy when it comes to memory.
Thanks again for the input.
Chris
-----Original Message-----
From: Mark W. Farnham [mailto:mwf@xxxxxxxx]
Sent: Friday, May 17, 2013 4:30 PM
To: Mark.Bobak@xxxxxxxxxxxx; Taylor Christopher - Nashville
Cc: oracle-l@xxxxxxxxxxxxx; ora_kclosson@xxxxxxxxx
Subject: RE: Prevent ASM from using any hugepages
I suppose you could startup mount the databases to have them suck up all the
allocated hugepages, start ASM, and then go back and alter the databases open.
(non-root kludge - but I don't see why it wouldn't work - NOT tested, I guess
you might have to use a file system pfile.)
I suppose you could have your boot sequence alter the permissions so ASM
couldn't access the hugepages and then after ASM is started but before you
start the databases, and reset the permissions so the databases can use the
hugepages. (That would require root, right? Or I suppose ASM and databases
could be different users, but that seems like a pain to me.)
So those are just ideas to try.
mwf
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Bobak, Mark
Sent: Friday, May 17, 2013 3:49 PM
To: Christopher.Taylor2@xxxxxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx; ora_kclosson@xxxxxxxxx
Subject: RE: Prevent ASM from using any hugepages
Sorry, forgot that MEMORY_TARGET is not available in 10g
I don't have any 10gRAC anymore, and very few 10g databases at all, so, I'm
also not sure if 10g has "use_large_pages" parameter? If so, set it to FALSE.
(Possible values are FALSE, TRUE, and ONLY.) But, if I recall correctly, that
parameter is not in 10g....
Guess it's not possible, in 10g, to use hugepages, but *not* for ASM?
-Mark
-----Original Message-----
From: Christopher.Taylor2@xxxxxxxxxxxx
[mailto:Christopher.Taylor2@xxxxxxxxxxxx]
Sent: Friday, May 17, 2013 3:42 PM
To: Bobak, Mark
Cc: oracle-l@xxxxxxxxxxxxx; ora_kclosson@xxxxxxxxx
Subject: RE: Prevent ASM from using any hugepages
You can't set sga_target in 10g ASM and I knew ASM used AMM in form or fashion
- so it was confusing me that it was reserving any hugepage entries.
-----Original Message-----
From: Bobak, Mark [mailto:Mark.Bobak@xxxxxxxxxxxx]
Sent: Friday, May 17, 2013 2:39 PM
To: Taylor Christopher - Nashville; odenysenko@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx; ora_kclosson@xxxxxxxxx
Subject: RE: Prevent ASM from using any hugepages
Chris,
Just use AMM (MEMORY_TARGET) for ASM, and it *can't* use hugepages. That's the
default set up, anyhow. So, just install ASM and forget it, and it won't touch
any hugepages.
That's how I have all my boxes set up.
I have to add:
Just got back from GLOC, had some discussions about hugepages with a few folks.
Still surprises me how many people don't bother with hugepages!
My three rules about hugepages are as follows:
1.) If you're not using hugepages, you're doing it wrong. Period. (Yes, ok,
for very tiny databases and low loads, it may not be worth the time.
But, what if that database gets busier over time? Just get used to doing it on
all your databases.)
2.) #1 doesn't apply to ASM instances.
3.) 'alter system set use_large_pages = ONLY;' is your friend.
-Mark
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Christopher.Taylor2@xxxxxxxxxxxx
Sent: Friday, May 17, 2013 3:13 PM
To: odenysenko@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx; ora_kclosson@xxxxxxxxx
Subject: RE: Prevent ASM from using any hugepages
I'd have to defer to other experts on whether it makes much difference to have
ASM in hugepages. From what I've read, there's really not much reason to have
asm using any hugepages.
Chris
From: Oleksandr Denysenko [mailto:odenysenko@xxxxxxxxx]
Sent: Friday, May 17, 2013 2:09 PM
To: Taylor Christopher - Nashville
Cc: oracle-l@xxxxxxxxxxxxx; ora_kclosson@xxxxxxxxx
Subject: RE: Prevent ASM from using any hugepages
Taylor,
ASM uses memory anyway so why not give hugepages to it ?
I see at least one benefit - if there will be paging on the system your ASM's
SGA will not be paged out.
Oleksandr Denysenko
17.05.2013 21:56 ÐÏÌØÚÏ×ÁÔÅÌØ
<Christopher.Taylor2@xxxxxxxxxxxx<mailto:Christopher.Taylor2@xxxxxxxxxxxx>>
ÎÁÐÉÓÁÌ:
The reason for this question was nitpicky - ASM is using about 14 hugepages
when it starts up which isn't much. Just kind of annoyed me - probably due to
lack of sleep lol
Chris
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>
[mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>]
On Behalf Of
Christopher.Taylor2@xxxxxxxxxxxx<mailto:Christopher.Taylor2@xxxxxxxxxxxx>
Sent: Friday, May 17, 2013 11:29 AM
To: oracle-l@xxxxxxxxxxxxx<mailto:oracle-l@xxxxxxxxxxxxx>
Subject: Prevent ASM from using any hugepages
Guys/Gals,
I'm in the process of configuring hugepages in 10.2.0.4 RAC.
Since ASM starts up first, how I do prevent it from using any of the hugepages?
Regards!
Chris Taylor
Oracle DBA
Parallon IT&S
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