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Cache size RRS feed

  • Question

  • We would like to use Steady State in an educational center for senior citizens. We wonder if the maximum cache size of 40GB will be large enough to contain all temporary changes during our six week's course period for 5 user groups. In our course there is no heavy file handling.

     

    After the six weeks course period we would like to return to the initial state by wiping out all changes.

     

    Is a noticeable slow-down of the performance of the computers to be expected?

     

     

    Tuesday, May 13, 2008 8:43 AM

Answers

  •  

    Could you let me know the usual operations on those computers so that we can check if 40GB is large enough? Meanwhile, the performance is based on several factors, such as hardware, operating systems. Please let me know the hardware and software environment and we can evaluate whether it may affect the computers' performance. But also please be assured that we do not need very powerful computer to enable the function.  

     

    Wednesday, May 14, 2008 2:54 AM
    Moderator
  •  

    For such scenario, I consider the cache size is enough for those users.

    Thursday, May 15, 2008 2:37 AM
    Moderator
  • Hi,

     

    SteadyState will show a warning message when the cache is 70% full, so if that's the cause of the reboot the user should have seen a warning.  The reboot won't occur until the cache is 85% full.

     

    Another possibility is that the computer is not being shut down cleanly.  If the shutdown is dirty, Windows Disk Protection will revert to discard mode.

     

    Thanks,

    Rob Elmer

    Development Lead

    Windows SteadyState

    Saturday, November 29, 2008 4:18 AM
  • Also, the 40GB maximum only applies to the size of the cache file that we automatically create.  The administrator is free to increase the size after Windows Disk Protection is installed.

     

    -Rob

    Saturday, November 29, 2008 4:21 AM
  • Thank you Rob for your answers.

     

    I checked the system log again carefully and I discovered indeed a mention that the computer had been shut down incorrectly and that WDP had switched to 'discard'. I think we switched off the current by accident.

     

    Still I think it is a pity, that SS is not robust in this respect.

     

    According to the manual the (absolute) maximum of the cache is 40 GB.  So, this is not quite true. I managed to increase the Vista-cache a bit, but not the XP-cache. Apparentely the absolute maximum is still 50% of the free space. This can leave a large free space, that cannot be used to increase the size of the cache.

     

    Wout

    Monday, December 1, 2008 2:09 PM
  • Hi,

    We're considering changes to this behavior of reverting to discard mode for a future version--you're not the only one with this request. 

    You're correct, the maximum cache size is 50% of the free disk space.  The reason that this limit is in place is that in order for the cache to be useful, there must be real free space on the disk too.  Imagine a disk with 100GB free space.  If you were to enable Windows Disk Protection and use an 80GB cache, then WDP would create a 80GB file on the disk which would leave you with 20GB of free space.  This means that you are limited to writing just 20GB of new data to the cache because you would then be left with 0 bytes of free disk space (even though the cache file itself is just 25% full).  Setting a limit of 50% provides the optimal balance between cache size and free space.

    Thanks,
    Rob Elmer
    Development Lead
    Windows SteadyState
    Tuesday, December 2, 2008 6:28 AM

All replies

  •  

    Could you let me know the usual operations on those computers so that we can check if 40GB is large enough? Meanwhile, the performance is based on several factors, such as hardware, operating systems. Please let me know the hardware and software environment and we can evaluate whether it may affect the computers' performance. But also please be assured that we do not need very powerful computer to enable the function.  

     

    Wednesday, May 14, 2008 2:54 AM
    Moderator
  • During the six week's period a maximum of 9 courses will take place (6 weeks x 2.5 hours). These are mainly basic and advanced courses. Basic course: working with the mouse, opening the start menu, making a folder, some simple word processing with Wordpad, working with Paint. Advanced course: using Internet Explorer, visiting websites and making some Favourites. Downloading and installing a simple program. Emailing with Outlook Express. As said: no heavy file handling.

     

    Each period also at least one more advanced course will be given: Word, Excel, Photo editing.

     

    We intend to buy new computers (good quality basic computers) and create dual boot systems: XP and Vista. Consequently there is no hard disk limit; we shall order hard disks as large as needed.

    Wednesday, May 14, 2008 7:18 PM
  •  

    For such scenario, I consider the cache size is enough for those users.

    Thursday, May 15, 2008 2:37 AM
    Moderator
  • Hi,

     

    We now installed a sample computer with XP SP3 and Vista Bus SP1, with Steady State and 5 users + 1 administrator. The cache size is the maximum of 40GB for each OS.

     

    As said, the computers are used for courses for seniors that take six weeks. The load is very low, because it concerns just basic computer use and internet&email. We set SS to 'Retain Changes Temporarily' for a period of 6 weeks and we have used the computer now for two course periods, but only the XP part.

     

    However,

     

    The  first period, SS cleaned all changes after a period of 4 weeks. The only reason we can imagine is that the cache was full.

     

    I put then System Restore OFF, because that takes a lot of space.

     

    The second period, SS cleaned all changes already after 3 1/2 weeks, again, we suppose, for the same reason.

     

    The logs, I put on a seperate partition, give no clue on what has happened. I cannot find a specific SS log either.

     

    We cannot imagine where over 30GB temporary files come from. The load from the users is very low. Automatic Updates is switched off in any case.

     

    Next time I will put our virus scanner to 'update manually' to prevent the cache to be filled with virus definitions; I hope this will help.

     

    It is very annoying, that we cannot keep changes during the whole period of 6 weeks. Can anybody give us some advice. Would it be possible, that there is a bug in SS, that causes it to clean prematurily?

     

    Thanks,

     

    Wout

     

     

    Friday, November 28, 2008 11:59 AM
  • Hi,

     

    SteadyState will show a warning message when the cache is 70% full, so if that's the cause of the reboot the user should have seen a warning.  The reboot won't occur until the cache is 85% full.

     

    Another possibility is that the computer is not being shut down cleanly.  If the shutdown is dirty, Windows Disk Protection will revert to discard mode.

     

    Thanks,

    Rob Elmer

    Development Lead

    Windows SteadyState

    Saturday, November 29, 2008 4:18 AM
  • Also, the 40GB maximum only applies to the size of the cache file that we automatically create.  The administrator is free to increase the size after Windows Disk Protection is installed.

     

    -Rob

    Saturday, November 29, 2008 4:21 AM
  • Thank you Rob for your answers.

     

    I checked the system log again carefully and I discovered indeed a mention that the computer had been shut down incorrectly and that WDP had switched to 'discard'. I think we switched off the current by accident.

     

    Still I think it is a pity, that SS is not robust in this respect.

     

    According to the manual the (absolute) maximum of the cache is 40 GB.  So, this is not quite true. I managed to increase the Vista-cache a bit, but not the XP-cache. Apparentely the absolute maximum is still 50% of the free space. This can leave a large free space, that cannot be used to increase the size of the cache.

     

    Wout

    Monday, December 1, 2008 2:09 PM
  • Hi,

    We're considering changes to this behavior of reverting to discard mode for a future version--you're not the only one with this request. 

    You're correct, the maximum cache size is 50% of the free disk space.  The reason that this limit is in place is that in order for the cache to be useful, there must be real free space on the disk too.  Imagine a disk with 100GB free space.  If you were to enable Windows Disk Protection and use an 80GB cache, then WDP would create a 80GB file on the disk which would leave you with 20GB of free space.  This means that you are limited to writing just 20GB of new data to the cache because you would then be left with 0 bytes of free disk space (even though the cache file itself is just 25% full).  Setting a limit of 50% provides the optimal balance between cache size and free space.

    Thanks,
    Rob Elmer
    Development Lead
    Windows SteadyState
    Tuesday, December 2, 2008 6:28 AM