FMS Cache Sizing ToolVersion 1.2User Guide

FMS Cache Sizing ToolUser GuideVersion 1.2

Introduction

The FMS Cache Sizing Tool is a Microsoft Excel spreadsheet designed to assist in the proper sizing of the FMS Fast Cache of the File Management System (FMS) modules FMS Server Cache (FSC) and FMS Client Cache (FCC). The FSC is the FMS network server component used to route and distribute Teamcenter data files to and from the Teamcenter systems volumes and transient volumes. The FCC is the client component used to cache recently accessed data in user-specific client environments.

The FMS Fast Cache is used by the FSC and FCC to store segment data. This cache is frequently used in conjunction with a whole file cache, which stores complete files.

Sizing the FMS Fast Cache

The FMS Fast cache is configured with five values that determine the size of its internal tables. The size of the internal tables in turn determines the caches data capacity, efficiency, and memory consumption. These values are known as the five magic numbers of an FMS Fast Cache configuration. A summary of these five values appears in the table below.

TableFCC NameFSC Read Cache NameFSC Write Cache Name

Core data segmentsFCC_MaximumNumberOfSegmentsFSC_MaximumReadCacheSegments FSC_MaximumWriteCacheSegments

Extent filesFCC_MaxExtentFilesFSC_MaximumReadCacheExtentFIlesFSC_MaximumWriteCacheExtentFIles

Extent file size (each)FCC_MaxExtentFileSizeMegabytesFSC_MaximumReadCacheExtentFileSizeMegabytes FSC_MaximumWriteCacheExtentFileSizeMegabytes

File headersFCC_MaximumNumberOfFilePagesFSC_MaximumReadCacheFilePages FSC_MaximumWriteCacheFilePages

GUID hash table sizeFCC_HashBlockPagesFSC_ReadCacheHashBlockPages FSC_WriteCacheHashBlockPages

The key to sizing an FMS Fast Cache is finding a set of five values which:1. Provides the desired cache capacity.2. Consumes no more than the available or allowable amount of shared memory.3. Allows efficient operation.4. Is internally consistent.The FMS Cache Sizing Tool provides a mechanism for sizing FMS Fast Caches for FSC and FCC installations by calculating the five magic numbers, checking them against the criteria listed above, and assembling them into XML that can be copied from the form and pasted into real FMS configuration files.

History

The FMS Cache Sizing Tool was preceded by a similar tool called FMSCalc. The FMSCalc tool was initially created to analyze FMS segment cache configurations for consistency. However, it did not compute cache sizes directly. The user needed to input the five magic numbers, or use a separate calculation mechanism (e.g., one of three methods described in the Teamcenter System Admin Guide), and then use the tool to adjust the cache configuration to suit the particular needs of the context for which the cache was being configured.The FMSCalc tool also had several generations and versions, not all of which were equally accurate in their internal memory computations, configuration limits, and warning thresholds. None of the FMSCalc tools were placed in source control until May 2012, and none of them were ever officially maintained by the FMS team (which maintains the FMS segment cache code) but unfortunately, many of the versions remain in use by customers and/or members of the customer support team (including GTAC).

The new FMS Cache Sizing Tool has the following goals and purposes:1. To provide an easy-to-use forward computation, starting with the platform context and the desired cache size, for initializing, customizing, and tuning the five magic numbers.2. To provide a consistent and accurate mechanism for cache size calculations, that reduces / eliminates guesswork and configuration errors on the part of Teamcenter customers and our own support staff.3. To take both disk and memory consumption into consideration, as they relate to segment cache sizing on a real machine with real resource limitations.4. To better match the memory considerations of the (read and write) pair of FSC segment caches to the available FSC server process memory. That is, to configure the FSC read and write caches as a pair, rather than individually; these two caches run in the same JRE process, and share common process memory space.The FMS Cache Sizing Tool also provides accurate analysis pages, which resemble the functionality of the existing FMSCalc tool.The FMS Cache Sizing Tool is versioned, and will continue to be maintained by the FMS development team, and included as part of the FMS deliverable kit.

PrerequisitesThe FMS Cache Sizing Tool is a Microsoft Excel 2010 spreadsheet intended to run on Microsoft Windows platforms. You will need Microsoft Excel (a part of the Microsoft Office suite of products) to use this tool.

Layout Overview

Input AreasInput areas are generally on the left side of each FMS Cache Sizing Tool page, and are identifiable by GREEN highlighting: The platform selector control has a bold green border.

All other input fields have a green tinted background with a bold green border.

Output AreaAt the bottom of each form is an output area containing the XML cache configuration.The XML output fields have a yellow tinted background and bold yellow border.

More Subtle Highlights Memory allocation and consumption values have a peach background.

Cache data size calculations and considerations have a pale blue background.

Some cache size data (not always visible) appear in pale blue text. On the calculation pages, the five magic numbers have a pale yellow background.

Errors, Warnings, and NoticesSome cells contain text that is only displayed when the cache configuration contains errors (inconsistent values), warnings (inefficiencies), or notices (positive features). These cells also have triangular markers pointing to the input or intermediate calculation to which they are related. Errors are displayed in RED TEXT. If you see errors on your form, you have at least one bad input or inconsistent value, which should be corrected before attempting to use the XML output (which may disappear). We will discuss below how to respond to cache configuration errors.

Warnings are displayed in ORANGE TEXT. If you see warnings on your form, there should be considered before using the XML configuration. The cache is usually functional, but warnings typically tell you about cache inefficiencies that may occur with this configuration; others just inform you that certain limits have been reached.

Notices are displayed in GREEN TEXT. These cells point out positive, desirable features of the cache configuration. You want to see as many green notices as possible, within the constraints of available memory and disk space.

Memory and Disk Consumption CalculationsEvery FMS Cache Sizing Tool page calculates the amount of memory and disk consumed by each of the data files in the current cache configuration, in both MB (megabyte) and GB (gigabyte) units. In general, the gigabyte values are more useful for large caches, and the megabyte values are more useful for smaller caches. For convenience, the FMS Cache Sizing Tool displays both.

Cache data is stored in two places: the segment file (fms.seg) and the extent files (fms*.ext). The core segment file contains fast, fully memory-resident segment data. The shared memory footprint and the size of this file grow and shrink with the number of core data segments. The extent files also contain segment data. The number of extent files and the size of each extent file are configurable. As these files are not fully memory-resident, access to the data in these files is not as fast as access to the core segment file. The other half of that tradeoff is that the shared memory footprint is much less affected by the size and number of extent files. The sum of the size of the segment file and all extent files is the total data capacity of the segment cache, and is subtotaled in a value called All Data (Ext+Seg). The metafile (fms.mf) is where the file headers are stored. It grows and shrinks with the number of file pages. There is one file header per file page. Like the segment file, the metafile is fully memory resident at all times, and contributes directly to the shared memory footprint. The metafile size is often the single most limiting factor when it comes to memory constraints. The hash file (fms.hsh) is where the GUID hash table is stored. It grows and shrinks with the number of hash pages. There are 128 hash entries per hash page. Like the segment file and the metafile, the hash file is fully memory resident at all times, and contributes directly to the shared memory footprint. Fortunately, the memory footprint of the hash table is much smaller than that of the metafile.The sum of the data space (segment and extent files), metafile, and hash file constitute the total memory or disk consumption of a segment cache.Memory consumption is a critical sizing parameter, particularly in 32-bit and FCC client environments, which have a 2GB total process memory limit. Memory can also be a limitation on 64-bit systems, especially if there is a limited amount of RAM available.

How to use the FMS Cache Sizing Tool

For sizing FCC or FSC caches:1. SELECT THE RIGHT PAGESelect the page that calculates the type of cache you want to size. The \FSCServerCalc/ page is the page which configures the FSC read and write caches (as a pair), from scratch. The \FCCClientCalc/ page is the page which configures the FCC segment cache, from scratch. Use the \OldHP_FSC/ and \OldHP_FCC/ pages only for cache configuration on Hewlett-Packard (HP-UX) systems prior to Teamcenter 8.1. For Teamcenter 8.1 and later, you can use the regular \FSCServerCalc/ and \FCCClientCalc/ pages.2. SELECT THE PLATFORM AND BITWIDTHSelect the appropriate platform and bit width value. (Use Unix for MacOS as well as Unix platforms.)NOTE: In order to be functional as a 64-bit process, the following requirements must all be met:a. The process must be running on a machine with 64-bit hardware.b. The process must be running on a 64-bit operating system.c. The software running in the process must have been compiled with a 64-bit instruction set. Java programs, in particular, need to be running in a Java Runtime Environment (JRE) that was compiled in 64-bit mode.All other processes are 32-bit processes.3. SET THE STARTING VALUES NEW in version 1.2: If you are using the version of the FMS Cache Sizing Tool with macros enabled, all the recommended input values, except for the cache sizes, will be updated for you whenever the platform / bitwidth selection changes. So change the platform / bitwidth first; then all you need to enter is the cache sizes.

The left-hand column contains recommended starting values for all of the inputs except the platform and the target cache size. These values may need to be tuned later, but please start with the recommended values when configuring a cache from scratch. Just type the green value in the input box to its right. For example,where you see this:

You would type 768 in the Memory (MB) this cache input field (which currently displays the value 1122).Please observe that the target values given as input are subject to change, due to rounding and internal cache limits, when the cache is initially sized. If you want to force a particular configuration change (for example, a hash ratio less than 1:1), you can use the analysis pages rather than the size calculation pages. but its probably best not to do this, as the resulting cache will be inefficient at best, and possibly non-functional in the end.

NOTE: Updating starting values from a prior configuration may place the form in some awkward transitional states. The advice here is to not worry about errors or warnings on the form until after all input values have been entered.

4. FIX ANY ERRORSOnce all the starting values are set, you look for the red ERRORs on the form first, and deal with those. A list of errors, and advice on how to handle them, appears here: INPUT ERROR This indicates that the form could not make sense of one or more of the inputs. One of them is incorrect out of range, negative, not a number, not a multiple of 16MB, or otherwise not acceptable. There should be another error displayed, typically in the left column, identifying which input is unacceptable. For example: MEM 256-1536This maximum amount of memory available to each process depends on the platform bitwidth, and the amount of RAM installed on the machine. This tool reserves some memory for typical FCC and FSC processes. The minimum allowable amount of memory allocated for each segment cache (e.g., on an FSC ser ver) is 256MB. CACHE SIZE > 0 For the purposes of this tool, the cache size (in megabytes) must be an integer value greater than zero. The maximum size of an FMS segment cache depends on the platform context and the amount of performance inefficiency that the user is willing to accept. SEG SIZE 1-2032For the purposes of this tool, segment file size must be at least one megabyte. The maximum size of the segment file depends on the platform context and the amount of memory available for segment data. EXT SIZE 16-2032The extent file size must be a multiple of 16 megabytes, between 16MB and a maximum value determined by the platform context. FILE RATIO 1-36This is the target ratio of the number of 16KB data segments in the cache to the number of file headers in the metafile. The minimum value is 1, and the maximum value is either 35 or 36, depending on the platform. HASH RATIO 1-10240This is the ratio of the number of file pages to the number of hash entries. (There are 128 hash entries per hash page.) OUT OF FILE PAGES. REDUCE CACHE SIZE. A cache of the requested size requires more file pages than the cache can support. The cache size must be reduced to bring the number of file pages down to a reasonable value. !! ERROR: OUT OF MEMORY !! THIS CACHE CONFIGURATION IS NOT USABLE. OUT OF MEMORY. REDUCE TARGET SEGMENT FILE SIZES, INCREASE TARGET FILE HEADER RATIOS, REDUCE TARGET HASH RATIOS, INCREASE CACHE MEMORY ALLOCATION.Either or both of these errors mean that there is not enough memory available to support this cache configuration. Memory can be conserved by a number of methods. We recommend considering memory conservation adjustments in this order:a. Reduce the target segment file size(s). This moves some of the segments into extent files, which use less memory.b. Increase the target file header ratio(s). This will have efficiency implications if most of the files in the cache store only a few 16KB segments of data in the cache. If the cache becomes starved for file headers, it will free the least recently accessed file, and its data segments, to make room for fresh data. This effectively reduces the size of the cache.c. FSC only: Make the read and write caches asymmetrical. (Typically, customers will make the write cache smaller than the read cache.) This can buy you additional memory for the more important read cache.d. Reduce the target hash ratio(s). This will decrease the efficiency of the cache because there will be a higher probability of hash collisions, and the collision chains will increase in size.e. Reduce the total cache size. If this becomes necessary, you are probably facing the reality that a cache of the intended size, if you did actually manage to shoehorn it into memory, would be so inefficient that it would be less useful or effective than a smaller cache, anyway. OUT OF HASH PAGES. REDUCE TARGET HASH RATIO. The cache cannot support the calculated or configured number of hash pages. Reducing the target hash ratio could free up some hash pages.If ERRORs are displayed on the page, the XML output may disappear and be replaced with a statement that there are errors on the page, that need to be corrected. This is intentional, (a deterrent to ignoring cache configuration errors, and creating support calls when the cache configuration does not work).5. TAKE NOTE OF ANY WARNINGS AND NOTICESOnce all of the red ERRORs have been addressed on the form, you should examine the orange WARNINGs. These cells make you aware of cache inefficiencies or potential problems that might be associated with the cache configuration as it stands.You can also note the notices, which indicate features configured to maximum performance. It is sometimes worthwhile to configure away a notice, if it also gets rid of a problematic or potentially problematic warning or error elsewhere on the form.A list of warnings, and advice on how to handle them, appears here: MAX EXT FILES (OK)(FSC only) This is just a notification that this cache uses the maximum number of extent files. The cache file size may have been increased to allow enough data in the cache. FILE HEADER RATIO INCREASED. NOTE: CACHE SIZE REDUCED WITH FILES

Example 2 (Out of memory on FSC)Consider a customer who wants an FSC read cache size of 1000 GB (1000 x 1024 = 1024000 MB), and an FSC write cache size of 500 GB (500 x 1024 = 512000 MB). The FSC is running on a 64-bit machine, running a Windows 7 64-bit operating system, with 8GB of RAM, and Teamcenter 8.3. The FSC cache would be configured as follows:1. Since this is an FSC configuration, starting with the cache size and working forward, select the \FSCServerCalc/ tab at the bottom left corner of the FMS Cache Sizing Tool spreadsheet.2. Since this customer is running Teamcenter 8.3, select as the platform. This is not a typo. Even though this is a 64-bit machine running a 64-bit operating system, Teamcenter 8.3 provides and runs in a 32-bit Java runtime environment (JRE). The least common denominator is the 32-bit JRE, which will limit the FSC to 2GB of total process memory.3. If you are not using the macro-enabled version of the FMS Cache Sizing Tool, or if you disabled the macros, enter the memory allocation value of 1536 into the Memory (MB) both fast caches input cell. Enter the other initial values from the leftmost column into the green input fields. Your form should now look like this:

4. There is an ERROR on the form. Where the XML output would normally be displayed, the text reads Error(s) on form.There is an error by the write cache File Pages setting, reading OUT OF FILE PAGES. REDUCE CACHE SIZE. You will notice that the File Ratio (cell O27) is 36.04:1. This is greater than the maximum file ratio on Windows (36:1). The number of file pages, however, is less than the maximum (which for 32-bit Windows is 2097151). This is because the FMS Cache Sizing Tool calculations were told to force-fit this cache into 512MB of memory. So the next question becomes: Where can I conserve a little more memory? Lets look at the recommendations associates with this error message above (page 6), in that order.a. Reduce the target segment file size(s). Reducing this (cell B23) to 15 MB (just 1MB less) solves the problem. The amount of data in memory will be minimal, but the percent residency of this size of a cache is already miniscule, so this will make no measurable difference in performance.b. Increase the target file header ratio(s). If you experiment, you will find that increasing the target file header ratio, even raising it to the maximum of 36:1, has no effect on the cache sizing calculations. The problem is that the memory cramp has already forced the file ratio to be too large. So theres nothing to be gained there.c. FSC only: Make the read and write caches asymmetrical. The customer has already done this. The read cache is twice the size of the write cache.d. Reduce the target hash ratio(s). Setting this (cell B29) to about 9.77:1 or less solves the problem, too. You lose a notice doing this, but a hash ratio of 9.77:1 is pretty close to the recommended 10:1 ratio, and once again no measurable performance difference.e. Reduce the total cache size. If you follow this course of action, a little trial-and-error will tell you that reducing the write cache size (cell B21) to about 510048 MB (498 GB) or less will do the trick and the customer may be willing to live with that.The process of arriving at a decision of how (and whether) to reduce the cache size, the segment file size, or the hash ratio is somewhat discretionary at this point. In this particular case, I would probably choose to reduce the segment file size. If I had to squeeze too much more cache into memory, I would be tempted to consider a combination of all of the above methods.

5. Now lets look at the WARNINGs.a. Both caches displays the warnings: FILE HEADER RATIO INCREASED. and NOTE: CACHE SIZE REDUCED WITH FILES < 576 KB. We know that the file ratios are maxed out; we know that this is a memory thing, and we know that were already stretched to the limit.b. The XML output of this cache appears as follows. This can be pasted into the section of the customers fsc.xml configuration file.

Example 3 (FCC cache)Consider a customer who wants an FCC segment cache size of 256GB (256 x 1024 = 262144 MB). The FSC is running on a 32-bit machine, running a Solaris 32-bit operating system, with 4GB of RAM, and Teamcenter 8.1. The FCC cache would be configured as follows:1. Since this is an FCC configuration, starting with the cache size and working forward, select the \FCCClientCalc/ tab in the bottom tab row of the FMS Cache Sizing Tool spreadsheet.2. Select Unix32 as the platform.3. If you are not using the macro-enabled version of the FMS Cache Sizing Tool, or if you disabled the macros, enter the memory allocation value of 1792 MB into the Memory (MB) fast cache input cell. Enter the other initial values from the leftmost column into the green input fields. Your form should now look like this:

4. There are some new text messages displayed, but there are no ERRORs on the form. The XML output is displayed, but is not yet optimized.5. Looking at WARNINGs and NOTICEs. I will start with the upper left and work clockwise around the form.a. The cell above the Ext File Size reads LARGE EXT SIZE (DELAYS) This is not a desirable situation. In order to make an FCC segment cache this large, the extent files need to be bigger than 64MB. That means cache operation (and therefore FCC operation) may occasionally pause for however long it takes to create an empty 272 MB extent file. The customer needs to know that this will happen. If this is not acceptable, then the segment cache size must be reduced.b. The cell next to the File Pages reads: FILE HEADER RATIO INCREASED. Because it is so large, this segment cache is configured to use the maximum number of file pages allowable for a 32-bit cache. The segment caches file header ratio (target value 1:1 from green input cell B13) has been increased to 8.01:1 (displayed in intermediate calculation cell O13) to allow the requested number of segments to be defined in the cache. This is not necessarily a cache capacity problem, as long as the cache is used to store enough data from each file (GUID).c. The cell next to the File Ratio reads: NOTE: CACHE SIZE REDUCED WITH FILES

Example 4 (64-bit FSC server)Consider a customer who wants an FSC read cache size of 1000 GB (1000 x 1024 = 1024000 MB), and an FSC write cache size of 500 GB (500 x 1024 = 512000 MB). The FSC is running on a 64-bit machine, running a SUSE Linux 10.0 64-bit operating system, with 8GB of RAM, and Teamcenter 8.3. The FSC cache would be configured as follows:1. Since this is an FSC configuration, starting with the cache size and working forward, select the \FSCServerCalc/ tab at the bottom left corner of the FMS Cache Sizing Tool spreadsheet.2. Since this customer is running Teamcenter 8.3 on a SUSE Linux, select Unix64 as the platform.3. If you are not using the macro-enabled version of the FMS Cache Sizing Tool, or if you disabled the macros, enter the initial values from the leftmost column into the green input fields, and enter 7680 as the maximum memory for both fast caches. Your form should now look like this:

6. There are some new text messages displayed, but there are no ERRORs on the form. The XML output is displayed, but is not yet optimized.7. Looking at WARNINGs and NOTICEs.a. The cell next to each caches File Pages reads: FILE HEADER RATIO INCREASED. The file ratio of both caches is approximately 6.8:1. The FMS Cache Sizing Tool has calculated the number of File Pages and Hash Pages that will fit in the allocated memory, and raised the file header ratio to fit in an 8GB process memory area. No problem here.b. The cell next to each caches File Ratio reads: NOTE: CACHE SIZE REDUCED WITH FILES

Example 5 (Analysis, resizing a cache)A customer used the FMSCalc tool to size their 100MB FCC cache two years ago, and now they want to expand their client cache. They added extent files to the old configuration, but the cache still does not seem to grow beyond the original 100MB size, and it never creates extent files. Whats wrong?

Here are the settings they used two years ago:

The new settings are:

They are expecting a cache size of 1600MB + 100MB = 1700 MB.

Plugging these values into the \FCCClientAnalyzer/ page of the FMS Cache Sizing Tool, we see what has happened:BEFORE:

AFTER:

What has happened here is that the old FMSCalc utility operated at the max file ratio (36:1), meaning that there are zero excess file pages. When the customer added segments, thinking that they were increasing the size of the cache, they added no additional file pages to reference those new segments. So the maximum amount of data that this cache can reference is all in the segment file. When the cache needs to add more data, it has to free a file page, which in turn frees 36 segments in the segment file, which it then uses for the new data. The cache never needs to create an extent file. Thus the NOT ENOUGH FILE PAGES error displayed on the form. There are not enough file pages to reference the segments in the extent files. The file ratio is a whopping 611:1!

To properly resize this cache, lets use the \FCCClientCalc/ page of the FMS Cache Sizing tool. Entering the proper input parameters, then copying the recommended segment file size of 1023MB into Target Segment File Size field, the output is as follows:

and all three NOTICEs are retained.(You might note that the actual cache size is 1711 MB. If you change the segment file size to 1012MB, you will get a very similar cache configuration thats exactly 1700 MB in size.)The customer can get a 1700 MB segment cache, with only 43 small extent files, and 700MB of free memory space to boot!

Example 5 Whats the biggest segment cache possible, and what cache size is optimum for me?That depends on a lot of qualifying parameters. Does the cache need to be efficient? How much memory can this cache consume? Is this running on Windows or Unix? Is it running on a 64-bit machine?Lets assume an FSC server on a 64-bit machine with 1000GB (1024000 MB) of RAM available (well leave the other 24 GB of its 1TB memory for the OS and a RAC client). Go to the \FSCServerCalc/ page of the FMS Cache Sizing tool, and start entering parametersSelect 64-bit Windows, and give it 1024000 MB of memory. Even if you are using the macros, override the recommended values by entering a target segment file size of 1MB, target 33554416MB per extent file, a target file header ratio of 36:1, and a nominal target hash ratio of 1:1. For the write cache, enter a nominal value of 1MB for the cache size, 1MB for the segment file size, a target file header ratio of 36:1, and a nominal target hash ratio of 1:1. Then keep cranking up the size until the first time it errors. The largest cache I can make out of this is 1170494128 MB (1143060 GB thats 1116 TB of segment cache).

Is this ridiculous? Yes, probably. This cache consumes 1000 GB of shared memory, almost all of which is in huge extent files. It has the worst possible file ratio, the worst possible hash ratio, a very big extent file size, and it will probably perform very poorly under duress.Will it work? I have no idea. I dont have a machine with a TB of RAM to test it with. But if I did, I would think it would probably take more than 3MB of RAM for the OS to manage the other 1000GB of shared memory.

A little more realistic is the maximum recommended cache sizeLets assume an FSC on a 64-bit Windows machine with 8GB of RAM available per FSC process, and a nominal 128MB write cache. Go to the \FSCServerCalc/ page of the FMS Cache Sizing tool, and start entering parameters64-bit Windows, give it 7680 MB of memory (leaving 512 MB for the rest of the FSC process), a target segment file size of 16MB, target 33554416MB per extent file, a target file header ratio of 1:1, and a nominal target hash ratio of 1:1. Then keep cranking up the size until the first time it shows a FILE RATIO INCREASED warning for the read cache. The largest cache I can generate is 207360 MB (about 202 GB).

Will this cache work? I havent personally tested it, but it has an acceptable file ratio, hash ratio, and extent file size, and it will probably perform quite well.

At this point, the tool will keep upping the file ratio until it maxes out at 36.00. So keep cranking up the size until the first time it errors. The largest cache I can make out of this is 7913088 MB (about 7728 GB or 7.5 TB). After that, I run OUT OF MEMORY. Depending on the customers actual file sizes, whether they are using this segment cache in conjunction with a whole file cache, and how much of each file is requested in random access mode, the optimum file ratio will vary, but the optimum cache size for most customers will probably lie somewhere between 200 GB and 5 TB.

Example 6 Whats the biggest segment cache possible on a legacy HP system?This gets much more constrained. Legacy HP systems did not support extent files, so all of the cache data had to be in the segment file. This means the segment cache had to have 100% data residency. In fact, this is such a special case that we were asked to add special \OldHP_FSC/ and \OldHP_FCC/ pages to the FMS Cache Sizing Tool to deal with these special cases. These function very much like the other pages, but differ from the normal Unix use cases in that: The number of extent files is always zero (0). The extent file size is always 16MB. The target segment file size is always the same as the target cache size.As a result, there are only three inputs per cache: The cache size, the file ratio, and the hash ratio.

Selecting the \OldHP_FSC/ and \OldHP_FCC/ pages, setting the target file header ratio to 1:1 and the target hash ratio to 10:1, a little experimentation gives us almost immediate results. (There is not much to tweak.)

32-bit (RISC):In a 32-bit environment, assuming a file header ratio of 1:1 and a hash ratio of 10:1, the largest possible cache is 1023 MB (almost 1GB). The limitation here is that this is the largest segment file that the segment cache allows.On an FSC, a 1023MB write cache also leaves room for a 500MB write cache with the same file header ratio and hash ratio.

64-bit (HP-Itanium):In a 64-bit environment, we recommend a maximum memory consumption of 8GB per FSC. FSC: Select the \OldHP_FSC/ page8192 MB memory, less 512 MB for the FSC, leaves 7680 MB available for the segment cache. Enter 7680 as the target memory (MB) for both caches.Lets assume that we can live with a write cache that is 10% of the size of the read cache. This number could be 50%, or whatever the customer chooses as a suitable ratio. We will set the write cache size as proportional to the read cache size, and then only manipulate the read cache size. The write cache size is cell B21, and the read cache size is cell B7. In cell B21, enter the following formula in the spreadsheet:=ROUNDDOWN(B7*0.1,0)Notice that as soon as this formula is entered, the value in cell B21 becomes 10% (or 50%, or one-third, etc.) of the read cache size (cell B7), rounded down to the nearest whole number. For example, I had a value of 1023 in cell B7, and cell B21 now contains the value 102.If you enter a constant number here, the formula will cease to function.Now increase the value in cell B7 until you see warnings or errors. I can get cache sizes of about 6744/674 MB before the file pages start to cramp, and 6970/697 MB before the caches run out of memory altogether.

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