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Possible to increase swap size for existing UFS-based drive slice?

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Operating Systems Solaris Possible to increase swap size for existing UFS-based drive slice?
# 8  
Old 04-25-2013
Quote:
Originally Posted by jlliagre
It should take seconds if you have Solaris 10 update 8 or newer. Might take minutes or even an hour if you have an older Solaris release (see https://blogs.oracle.com/sistare/ent...d_fast_memstat )

So according to prstat, you have 16 GB of memory. Do you feel there is still a problem to solve ?
I'm running mdb now...Guess I have the older updates....it's taking a while.

How do you figure that I have 16GB of memory from the prstat output.

I'm just wondering if the low swap size (516.xx MB) will the zones be able to use the whole installed 16 GB of memory?
And if I were to increase via the use of swap file, I only need to touch the global zone right?

Thanks again!
# 9  
Old 04-25-2013
Quote:
Originally Posted by JT-KGY
How do you figure that I have 16GB of memory from the prstat output.
zone3 is using 2432M which is reported as 15% of the memory.

2432/15*100=16213
Quote:
I'm just wondering if the low swap size (516.xx MB) will the zones be able to use the whole installed 16 GB of memory?
The risk is high part of your RAM will be unusable because of virtual memory reservation.
You swap area is likely too small given the RAM size.
Quote:
And if I were to increase via the use of swap file, I only need to touch the global zone right?
Yes, the swap area is to be handled by the global zone.
# 10  
Old 04-25-2013
mdb result came back....

Code:
# echo ::memstat | mdb -k

Page Summary                Pages                MB  %Tot
------------     ----------------  ----------------  ----
Kernel                    1221615              9543   58%
Anon                       536894              4194   26%
Exec and libs               25471               198    1%
Page cache                   1259                 9    0%
Free (cachelist)             6015                46    0%
Free (freelist)            300019              2343   14%

Total                     2091273             16338
Physical                  2045044             15976

Not sure how to read it though......


And if I were to add swap file to my system... should I shut down my containers in order to do so?


Also although my global zone is running UFS... it has a large ZFS that all the containers run on... would you recommend that I create the swap file on the ZFS or UFS filesystem?


Thank you!
# 11  
Old 04-25-2013
Quote:
Originally Posted by JT-KGY
mdb result came back....

[code]Not sure how to read it though......
You have your 16 GB visible and around half of it is used a ZFS cache, which is fine. You still have RAM available so nothing to worry here.
Quote:
And if I were to add swap file to my system... should I shut down my containers in order to do so?
No, you can add and remove swap on a live system.
Quote:
Also although my global zone is running UFS... it has a large ZFS that all the containers run on... would you recommend that I create the swap file on the ZFS or UFS filesystem?
You might have no choice but to use UFS.

I suspect swap volumes not to be supported on a RAID-Z pool. At least I never saw such a configuration. Same issue with swap files that are likely still unsupported on ZFS.
# 12  
Old 04-25-2013
Thanks jlliagre!

How do you figure that half of it is ZFS cache?
Is it the ZFS ARC cache that I kept reading about?

I also ran kstat and got this
Code:
# kstat zfs:0:arcstats:size | grep size | awk '{printf "%2dMB\n",  $2/1024/1024+0.5}'
6587MB

Looks like it's using 6.5GB in ZFS cache....

Is this normal.... or should I be using
zfs_arc_max and zfs_arc_min to limit how much cache ZFS can use...

And having that the Oracle 8i is running off the ZFS volume... what is better? more available memory
or more ZFS cache... (Sorry.. I know this is a bit OT)


Quote:
Originally Posted by jlliagre
You have your 16 GB visible and around half of it is used a ZFS cache, which is fine. You still have RAM available so nothing to worry here.
# 13  
Old 04-25-2013
Quote:
Originally Posted by JT-KGY
Thanks jlliagre!

How do you figure that half of it is ZFS cache?
Because a kernel doesn't use 9.5 GB so the ZFS ARC is likely using a large part of it.
Current Solaris ::memstat separate the ZFS releated memory from the rest of kernel usage.
Quote:
Is it the ZFS ARC cache that I kept reading about?
Indeed.
Quote:
I also ran kstat and got this
Code:
# kstat zfs:0:arcstats:size | grep size | awk '{printf "%2dMB\n",  $2/1024/1024+0.5}'
6587MB

Looks like it's using 6.5GB in ZFS cache....

Is this normal.... or should I be using
zfs_arc_max and zfs_arc_min to limit how much cache ZFS can use...
There is no point limiting the cache size (outside very specific cases).
Quote:
And having that the Oracle 8i is running off the ZFS volume... what is better? more available memory
or more ZFS cache... (Sorry.. I know this is a bit OT)
Unused memory is wasted memory. More of the memory is used for cache, better the performance.
# 14  
Old 04-26-2013
Quote:
Originally Posted by jlliagre
Because a kernel doesn't use 9.5 GB so the ZFS ARC is likely using a large part of it.
Current Solaris ::memstat separate the ZFS releated memory from the rest of kernel usage.
Indeed.There is no point limiting the cache size (outside very specific cases).

Unused memory is wasted memory. More of the memory is used for cache, better the performance.

Well... the whole point of my investigation is to find out if I can coax out more
performance out of my current setup. I like to have the oracle zone (zone3)
use more memory to improve performance....

Also ZFS does tend to slow down dramatically after the system has been up
for a while... to the point that login onto the shell would take some 10
seconds... any access to the disk takes longer to respond..etc.

Is there any way to refresh the ZFS cache?

Thank you jlliagre!
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