Verifying and seting file system cache parameters

I have a Solaris 10 system that has 64Gb of memory that is running a Sybase database with raw devices. Based on the output of "echo ::memstat | mdb -k" it looks like I have about 5Gb of memory being chewed up by filesystem caching which is really not a big deal for us. Can anyone point me to the way for changing the default filesystem caching parameters so I can free up some of this memory?
EDIT: One last thing is that we're using VxVM for this system with all non-system filesystems being VxFS. That's basically just our dump and tempdb filesystems.
# echo ::memstat | mdb -k
Page Summary Pages MB %Tot
Kernel 424258 3314 5%
Anon 7004059 54719 85%
Exec and libs 21785 170 0%
Page cache 57433 448 1%
Free (cachelist) 664030 5187 8%
Free (freelist) 48494 378 1%
Total 8220059 64219
Physical 8189297 63978
Edited by: trouphaz on May 10, 2010 12:49 PM

So, the memory listed under Free (cachelist) is also useable by applications? I thought that stuff was dedicated to the filesystem cache, which is really unnecessary for our system. Almost all IO on this system is through raw devices and the rest is on VxFS filesystems.

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Warming up File System Cache for BDB Performance

Hi,
We are using BDB DPL - JE package for our application.
With our current machine configuration, we have
1) 64 GB RAM
2) 40-50 GB -- Berkley DB Data Size
To warm up File System Cache, we cat the .jdb files to /dev/null (To minimize the disk access)
e.g
// Read all jdb files in the directory
p = Runtime.getRuntime().exec("cat " + dirPath + "*.jdb >/dev/null 2>&1");
Our application checks if new data is available every 15 minutes, If new Data is available then it clears all old reference and loads new data along with Cat *.jdb > /dev/null
I would like to know that if something like this can be done to improve the BDB Read performance, if not is there any better method to Warm Up File System Cache ?
Thanks,

We've done a lot of performance testing with how to best utilize memory to maximize BDB performance.
You'll get the best and most predictable performance by having everything in the DB cache. If the on-disk size of 40-50GB that you mention includes the default 50% utilization, then it should be able to fit. I probably wouldn't use a JVM larger than 56GB and a database cache percentage larger than 80%. But this depends a lot on the size of the keys and values in the database. The larger the keys and values, the closer the DB cache size will be to the on disk size. The preload option that Charles points out can pull everything into the cache to get to peak performance as soon as possible, but depending on your disk subsystem this still might take 30+ minutes.
If everything does not fit in the DB cache, then your best bet is to devote as much memory as possible to the file system cache. You'll still need a large enough database cache to store the internal nodes of the btree databases. For our application and a dataset of this size, this would mean a JVM of about 5GB and a database cache percentage around 50%.
I would also experiment with using CacheMode.EVICT_LN or even CacheMode.EVICT_BIN to reduce the presure on the garbage collector. If you have something in the file system cache, you'll get reasonably fast access to it (maybe 25-50% as fast as if it's in the database cache whereas pulling it from disk is 1-5% as fast), so unless you have very high locality between requests you might not want to put it into the database cache. What we found was that data was pulled in from disk, put into the DB cache, stayed there long enough to be promoted during GC to the old generation, and then it was evicted from the DB cache. This long-lived garbage put a lot of strain on the garbage collector, and led to very high stop-the-world GC times. If your application doesn't have latency requirements, then this might not matter as much to you. By setting the cache mode for a database to CacheMode.EVICT_LN, you effectively tell BDB to not to put the value or (leaf node = LN) into the cache.
Relying on the file system cache is more unpredictable unless you control everything else that happens on the system since it's easy for parts of the BDB database to get evicted. To keep this from happening, I would recommend reading the files more frequently than every 15 minutes. If the files are in the file system cache, then cat'ing them should be fast. (During one test we ran, "cat *.jdb > /dev/null" took 1 minute when the files were on disk, but only 8 seconds when they were in the file system cache.) And if the files are not all in the file system cache, then you want to get them there sooner rather than later. By the way, if you're using Linux, then you can use "echo 1 > /proc/sys/vm/drop_caches" to clear out the file system cache. This might come in handy during testing. Something else to watch out for with ZFS on Solaris is that sequentially reading a large file might not pull it into the file system cache. To prevent the cache from being polluted, it assumes that sequentially reading through a large file doesn't imply that you're going to do a lot of random reads in that file later, so "cat *.jdb > /dev/null" might not pull the files into the ZFS cache.
That sums up our experience with using the file system cache for BDB data, but I don't know how much of it will translate to your application.

888k Error in ULS Logs for File System Cache

Hello,
We have a SharePoint 2010 farm in a three-tier architecture with multiple WFEs and APP servers.
Roughly once a week we will have a number of WFEs seize up and jump to 100% CPU usage. Usually they come in pairs; two servers will jump to 100% at the same time while all the other servers are fine in the 20% - 50% range.
Corresponding to the 100% CPU spike, the following appear in the ULS logs:
"File system cache monitor encoutered error, flushing in memory cache: System.IO.InternalBufferOverflowException: Too many changes at once in directory:C:\ProgramData\Microsoft\SharePoint\Config\<GUID>\."
When these appear, the ULS logs will show hundreds back-to-back flooding the logs.
I have yet to figure out how to stop these and bring the CPU usage down while the incident is happening, and how to prevent them in the future.
While the incident is happening, I have tried clearing the configuration cache, shutting the timer jobs down on each server, deleting all the files but config.ini in the folder listed above, changing config.ini to 1, and restarting the timer. The CPU will
drop momentarily during this process, but as soon as all the timer jobs are restarted the CPUs jump back to 100% on the same servers.
This week as part of my weekly maintenance I thought I'd be proactive and clear the cache even though the behavior wasn't happening, and all CPUs were normal. As soon as I finished, the CPU on two servers that were previously fine jumped to 100% and wouldn't
come down. Needless to say, users complain of latency when servers are at 100% CPU.
So I am frustrated. The only thing I have found that works when the CPUs jump to 100% with these errors are a reboot. Nothing else, including IISReset and stopping/starting the admin and timer job services work. Being Production systems, reboots during the
middle of the day are bad.
Any ideas? I have scoured the Internet resources on this error and have come up relatively empty-handed. All the articles reference clearing the configuration cache, which, in my instance, does not get rid of these issues, and can even trigger them.
Thanks,
Joseph Irvine

Take a look at http://support.microsoft.com/kb/952167 for the list of recommended exclusions per Microsoft.
Trevor Seward
Follow or contact me at...
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This post is my own opinion and does not necessarily reflect the opinion or view of Microsoft, its employees, or other MVPs.

File system cache on APO for ATP

Hi, aces,
Do you have any recommendation percentage of file system cache on AIX for APO/ATP environment? My system was configured to be 20% min -80% max. But I am not sure if this is good for APO/ATP.
I suspect the file system cache takes a lot of memory and leaves less memory for APO work processes.
Regards,
Dwight

sar will give you what you need....

Windows Embedded Standard File system cache

Hey I am new in Windows Embedded.
I am using Windows Embedded Standard XP, and looking for information regarding cache and file system in OS.
File Systems are designed to reduce the disk hits. File write operations does not write to disk immediately until we use the flush API. Flush API makes the system slower though. Os on the other hand keeps flushing the data in optimized way.
We need to know
1- how frequent windows embedded standard is flushing the data. ?
2- How much data it keeps in file system cache(Ram) before flushing ?
3- Can we change things mentioned in above two points by using code?

Ok Thank you very much .
How much data it keeps in file system cache(Ram) before flushing ? How much cache memory i have on ram
How we know this ?

Difference between ASM Disk Group, ADVM Volume and ACFS File system

Q1. What is the difference between an ASM Disk Group and an ADVM Volume ?
To my mind, an ASM Disk Group is effectively a logical volume for Database files ( including FRA files ).
11gR2 seems to have introduced the concepts of ADVM volumes and ACFS File Systems.
An 11gR2 ASM Disk Group can contain :
ASM Disks
ADVM volumes
ACFS file systems
Q2. ADVM volumes appear to be dynamic volumes.
However is this therefore not effectively layering a logical volume ( the ADVM volume ) beneath an ASM Disk Group ( conceptually a logical volume as well ) ?
Worse still if you have left ASM Disk Group Redundancy to the hardware RAID / SAN level ( as Oracle recommend ), you could effectively have 3 layers of logical disk ? ( ASM on top of ADVM on top of RAID/SAN ) ?
Q3. if it is 2 layers of logical disk ( i.e. ASM on top of ADVM ), what makes this better than 2 layers using a 3rd party volume manager ( eg ASM on top of 3rd party LVM ) - something Oracle encourages against ?
Q4. ACFS File systems, seem to be clustered file systems for non database files including ORACLE_HOMEs, application exe's etc ( but NOT GRID_HOME, OS root, OCR's or Voting disks )
Can you create / modify ACFS file systems using ASM.
The oracle toplogy diagram for ASM in the 11gR2 ASM Admin guide, shows ACFS as part of ASM. I am not sure from this if ACFS is part of ASM or ASM sits on top of ACFS ?
Q5. Connected to Q4. there seems to be a number of different ways, ACFS file systems can be created ? Which of the below are valid methods ?
through ASM ?
through native OS file system creation ?
through OEM ?
through acfsutil ?
my head is exploding
Any help and clarification greatly appreciated
Jim

Q1 - ADVM volume is a type of special file created in the ASM DG. Once created, it creates a block device on the OS itself that can be used just like any other block device. http://docs.oracle.com/cd/E16655_01/server.121/e17612/asmfilesystem.htm#OSTMG30000
Q2 - the asm disk group is a disk group, not really a logical volume. It combines attributes of both when used for database purposes, as the database and certain other applications know how to talk "ASM" protocol. However, you won't find any general purpose applications that can do so. In addition, some customers prefer to deal directly with file systems and volume devices, which ADVM is made to do. In your way of thinking, you could have 3 layers of logical disk, but each of them provides different attributes and characteristics. This is not a bad thing though, as each has a slightly different focus - os file system\device, database specific, and storage centric.
Q3 - ADVM is specifically developed to extend the characteristics of ASM for use by general OS applications. It understands the database performance characteristics and is tuned to work well in that situation. Because it is developed in house, it takes advantage of the ASM design model. Additionally, rather than having to contact multiple vendors for support, your support is limited to calling Oracle, a one-stop shop.
Q4 - You can create and modify ACFS file systems using command line tools and ASMCA. Creating and modifying logical volumes happens through SQL(ASM), asmcmd, and ASMCA. EM can also be used for both items. ACFS sits on top of ADVM, which is a file in an ASM disk group. ACFS is aware of the characteristics of ASM\ADVM volumes, and tunes it's IO to make best use of those characteristics.
Q5 - several ways:
1) Connect to ASM with SQL, use 'alter diskgroup add volume' as Mihael points out. This creates an ADVM volume. Then, format the volume using 'mkfs' (*nix) or acfsformat (windows).
2) Use ASMCA - A gui to create a volume and format a file system. Probably the easiest if your head is exploding.
3) Use 'asmcmd' to create a volume, and 'mkfs' to format the ACFS file system.
Here is information on ASMCA, with examples:
http://docs.oracle.com/cd/E16655_01/server.121/e17612/asmca_acfs.htm#OSTMG94348
Information on command line tools, with examples:
Basic Steps to Manage Oracle ACFS Systems

File system cache performance

hi.
i was wondering if anyone could offer any insight into how to
assess the performance of the file system cache. I am interested
in things like hit rate (which % of pages read are coming from the
cache instead of from disk), the amount of data read from the cache
over a time span, etc.
outside of the ::memstat dcmd for mdb, i cannot seem to find a whole lot about this topic.
thanks.

sar will give you what you need....

AIX File system caching

Dear Experts,
How to disable file system caching in aix environment?
Thanks in advance.
Regards,
Rudi

> How to disable file system caching in aix environment?
This depends on the filesystem used.
Check http://stix.id.au/wiki/Tuning_the_AIX_file_caches
Markus

New zone and inherited file system mount point error

Hi - would anyone be able to help with the following error please. I've tried to create a new zone that has the following inherited file system:
inherit-pkg-dir:
dir: /usr/local/var/lib/sudo
But when I try to install it fails with:
root@tdukunxtest03:~ 532$ zoneadm -z tdukwbprepz01 install
A ZFS file system has been created for this zone.
Preparing to install zone <tdukwbprepz01>.
ERROR: cannot create zone <tdukwbprepz01> inherited file system mount point </export/zones/tdukwbprepz01/root/usr/local/var/lib>
ERROR: cannot setup zone <tdukwbprepz01> inherited and configured file systems
ERROR: cannot setup zone <tdukwbprepz01> file systems inherited and configured from the global zone
ERROR: cannot create zone boot environment <tdukwbprepz01>
I've added this because unknown to me when I installed sudo from sunfreeware in the global it requires access to /usr/local/var/lib/sudo - sudo itself installs in /usr/local. And when I try to run any sudo commands in the new zone it gave this:
sudo ls
Password:
sudo: Can't open /usr/local/var/lib/sudo/tdgrunj/8: Read-only file system
Thanks - Julian.

Think I've just found the answer to my problem, I'd already inherited /usr ..... and as sudo from freeware installs in /usr/local I guess this is never going to work. I can only think to try the sudo version of the Solaris companion DVD or whatever it's called.

Oracle cache and File System cache

on the checkpoint, oracle cache will be written to disk. But, If an oracle database is over file system datafile, it likely that the data are still leave in FileSystem cache. I don't know how could oracle keep data consistency.

Thanks for your feedback. I am almost clear about this issue now, except one point need to be confirmed: do you mean that on linux or unix, if required, we can set "direct to disk" from OS level, but for windows, it's default "direct to disk", we do not need to set it manually.
And I have a further question: If a database is stored on a SAN disk, say, a volume from disk array, the disk array could take snapshot for a disk on block level, we need to implement online backup of database. The steps are: alter tablespace begin backup, alter system suspend, take a snapshot of the volume which store all database files, including datafiles, redo logs, archived redo logs, controll file, service parameter file, network parameter files, password file. Do you think this backup is integrity or not. please note, we do not flush the fs cache before all these steps. Let's assume the SAN cache could be flushed automatically. Can I think it's integrity because the redo writes are synchronous.

Missing Recovery Partition and Unrecognized File Systems

So, a long time ago I accidentally deleted my recovery partition and have recently been trying to fix it so that I can upgrade my OS to Mavericks. After browsing around here I found the Recovery Partition Creator 3.7 and used it to create a new recovery partition. Using the diskutil list command everything seemed to be fine and it looked like the partition was successfully created so I tried reinstalling OS X Lion by holding command R at startup. Doing so brought up the internet recovery menu and I selected reinstall Lion which was still unsuccessful because "a recovery partition could not be created". So, I decided to check in disk utility to see what might be wrong and I used the disk utility debug command in order to access disk utility's debug menu and show all the hidden partitions. Now, looking at these partitions I see two hidden partitions: disk0s1 which is an EFI partition, and disk0s3 which is the Apple Boot Partition that was created by Recovery Partition Creator 3.7. After verifying the partitions, disk utility is telling me that both my EFI and apple boot partitions have unrecognized file systems, my Macintosh HD partition is fine. At this point I do not know what to do.
Below are photos of the diskutil list and of what disk utility is showing me for the two hidden partitions.
For reference I am running OSX Lion 10.7.5 (11G63) on a early 2011 13 inch Macbook Pro (Base Model).
Bootrom version: MBP81.0047.B27
SMC Version: 1.68f99
Thank you all in advance for your help, feel free to ask me any questions.

Just an update, I went ahead and installed Lion again over the existing TM restored installation using the Lion Update file and at least File Vault is working. Interestingly, I still do not have a Recover partition so obviously something new for Apple Support to learn.

APEX 2.1 and server file system interaction methods

Hello experts
I am building a web application using APEX 2.1 that would be used by a few hundred users as a secure and auditable portal to a word document file library.
The main use case is that an authenticated user will find links to documents he/she has been granted access of various levels (read only or read/write).
All the files are stored on the server file system.
I have a couple of questions:
1.some file" when placed in an HTML region source does not work. Is this normal ?
2.Will I have to import the entire file library (very large in size and number of files) into APEX so I can access them from APEX or can I simply use the simple anchor HTML tag above.
Many thanks. Zemus.
Edited by: zemus on Jun 4, 2009 1:25 PM
Edited by: zemus on Jun 4, 2009 1:26 PM
Edited by: zemus on Jun 4, 2009 1:27 PM

I think I answered your email. Also, you can have a look at these threads:
Re: How to display bfile in Apex report
Re: Linking to display an external file
Denes Kubicek
http://deneskubicek.blogspot.com/
http://www.opal-consulting.de/training
http://apex.oracle.com/pls/otn/f?p=31517:1
-------------------------------------------------------------------

File system and LR2 file system view summary

Hello,
Is there a way when navigating a directory via the Folders panel to click on the folder and get summary information about the contents of the folder both from a file system perspective as well as a Lightroom perspective?
file system perspective: number of physical files supported by LR2 in the folder
LR2 perspective: the number of files that have virtual copies, how many total virtual copies total, how many photos are in stacks, how many stacks, etc.
Thanks,
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               No, you can't specify an entire filesystem as something to cluster. I
          suggest using NFS or some shared filesystem and then running a cluster
          off of that.
                                   - Mike
          Michael Lenart wrote:
          >
          > yes
          > "Mike Benham" <[email protected]> wrote in message
          > news:[email protected]..
          > >
          > >
          > >
          > > I'm not sure if I understand what you're asking. How can you cluster a
          > > filesystem? It seems like you want to mount some filesystem via NFS and
          > > then access that from each instance of a server? Are you asking if
          > > Weblogic can perform the duty of NFS?
          > >
          > > - Mike
          > >
          > >
          > > Michael Lenart wrote:
          > > >
          > > > Can the file system be clustered?? For example, in the cluster level
          > > > property file can I have a file system with the name of XDrive and then
          > use
          > > > that file system in my components??

Please Advise on SAP and DB2 file system during installation

Dear Experts
SAP ERP 6.0 EHP5 ( AS ABAP and AS JAVA(EP))
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PRD server: 2*300GB HDD 2cpu/32gb ram
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1 TAPE DEVICE
these three server should to connected to storage
Its my first time to work on this kind of landscape with SAN
Request to please provide me filesytems and mountpoint with size. However i am going through standardinst document & trying to understand...
Regards
Raju

RAJU83 wrote:
> Request to please provide me filesytems and mountpoint with size. However i am going through standardinst document & trying to understand...
Better you continue with that and plan and document the file system and size strategy.
'SAP Sizing' is very important, utilize it - service.sap.com/sizing
After you understand the guides' advice and explore standard sizing, then share your queries with us.
This concept is very detailed one and really the 'subjective' one - depends case to case - customer to customer - ultimately the SIZING will help you - It can't be explained clearly in a discussion thread 'initially'
Thanks

Flash Player 9, Director MX, LocalConnection and the file system sandbox

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access. Previously I could use LocalConnection in a Flash Player 8
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I know that this is a rather general and abstract question:
put simply, does anyone know whether Flash Player 9 and Director MX
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ps to pre-empt over-enthusiastic respondees, yes I am aware
of other technologies such as AIR, Zinc etc, and no they're not a
viable option for my particular project.

Hi,
the following sourcecode is compiled with Flexbuilder 2 and
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best regards,
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Verifying and seting file system cache parameters

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