SBS hangs or restarts with low free disk space or fragmentation (259421)

SYMPTOMS

Computers running Small Business Server 4.0, 4.0a, or 4.5 may exhibit one or more of the following symptoms:

The computer stops responding (hangs) unexpectedly, infrequently, or at random intervals.
The computer hangs, or automatically restarts (often without error messages in the event logs).
The computer randomly hangs or automatically restarts (often without error messages being written to the event logs).
The computer repeatedly hangs or automatically restarts at predictable intervals (often without error messages being written to the event logs).
The computer or services start up or shut down slowly.
Loading or saving files is slow or does not work.
Computer startup does not finish successfully; the computer hangs or is restarted.
There is less than 10 percent available drive space.
There are unusual, intermittent, or persistent printing/fax/spooler problems.
There are delays or slowdowns.
There are serious backup problems.
There are other seemingly random and hard to diagnose computer instabilities.

CAUSE

These symptoms can occur if there is significant file fragmentation or not enough available disk space. File fragmentation or a lack of sufficient disk space can cause the following conditions:

A lack of contiguous or useable file storage space.
The inability of the Master File Table to dynamically increase its allocated space or to use existing allocated space as file storage space, including the necessary directory pointers.
The inability of temporary files or folders or log files to dynamically increase at startup or during computer operation (including the paging file, temporary files, and temporary folders).
The Master File Table reserved space is filled with file fragments that are larger than 4KB in size.
There is widespread file corruption or corruption of specific computer-level files, such as registry files, event logs, or cache files.
There are erroneous error messages such as "File not found or is missing" caused by time-outs during attempts to load or save a file.
Corrupted startup files are not loaded properly after a restart.

By design, Small Business Server 4.0 and 4.0a are installed on a 2GB primary partition with drive C as both the boot and computer partition. This partition is initially formatted with the FAT file system and converted to the NTFS file system during installation. With average data and user profile levels, the boot/computer partition is likely to be filled past its useable capacity.

If you attempt an upgrade to Small Business Server 4.5 without moving any files off of drive C, the required 1.3 GB of free disk space is probably not available. The unsuccessful upgrade attempt may use up even more space on the drive, leading to further fragmentation.

If you applied the upgrade after moving or deleting sufficient files or programs, even if the upgrade was successful, it most likely left the partition in a fragmented state and without useable file storage space for any meaningful future use of the server, regardless of the available free disk space.

The cause and effects of problems relating to fragmentation and filled drives are exacerbated as the formatted sector size increases (especially at 4KB and larger). For most administrators, the formatted sector size for a partition is not of concern during partition creation. Any computer that has changes to drive geometry, including the formatted sector sizes, after installation (including the use of third-party utilities to make these low-level changes) is not supported by Microsoft because of the potential impact and severity of possible incompatibilities with standard Windows NT formats.

In addition, on computers with larger formatted sector sizes, the ability to successfully back up, migrate, repair or even apply emergency disaster recovery techniques by using procedures such as defragmentation may be substantially if not totally eliminated.

RESOLUTION

When a drive or partition fills completely (or to the point that the Master File Table is used for file space for files larger than 4KB in size), the only permanent solution is to make a complete backup of the drive or partition, and then repartition and format all partitions on the physical disk. Then, restore the computer to its prior state from the backup, or reinstall the operating system and programs, and then restore the data from tape.

For computers that are running very slowly, or that need to be stabilized or returned to working order after a crash, temporary workarounds or short-term fixes may include some or all of the following items:

Move the Temp folder to another drive.
Move data folders and/or files to another drive.
Delete unneeded browser, proxy, Microsoft Internet Information Server (IIS), and other cache files. (Archive them first if needed.)
Archive, move, or delete unneeded Memory.dmp and User.dmp files.
Archive, reset or delete log files.NOTE: Take care not to delete Microsoft Exchange log files unless you make copies or backups because they may be needed for recovery of the Exchange store.
Stop or disable any unnecessary processes, especially those that create or add to traces, log files, databases, or captures of data streams.
Stop or disable any unnecessary logging or caching features or programs or system processes.
Temporarily turn off or disable any virus checking, both by software and hardware (BIOS).
Move the Pagefile.sys file to another drive.NOTE: if the paging file is absent on the computer partition, or is less than existing RAM in size, a memory dump file will not be written to disk in the event of a computer crash.
If you cannot move the paging file, match the maximum and minimum size to reduce file fragmentation (this does not affect the internal structures of the file because data within it is not written contiguously by design).
After you create as much free space as possible, run a file defragmentation program to consolidate fragmented files and random blocks of file storage marked for storage use as contiguous blocks of free space.

Without recommending any specific third-party product, examples of this type of software include Executive Software Diskeeper and Symantec Norton SpeedDisk.

A 30 day, no-charge trial copy of Diskeeper 5.0 (the current version as of 4/4/2000) is available for download at:

http://www.diskeeper.com

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.

The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

WARNING: Before using any program for file defragmentation on any version of Microsoft BackOffice Small Business Server, verify that it is designed specifically to work with Small Business Server. At minimum, it must be designed for the NTFS file system running on Microsoft Windows NT Server 4.0 or later.

Do not use any defragmentation software that is included with or designed specifically for Microsoft Windows 95 or Microsoft Windows 98 to defragment any version of SBS Server or data corruption and/or data loss could occur.

MORE INFORMATION

Registry hives, log files, and databases (such as the Exchange .edb files) may be the most fragmented files on the drive. Corruption of event log files, IIS metabase, and proxy cache files can also exhibit many of these symptoms.

It is easier (and the potential for data loss is less) if you try to "recover" a server before final failure than to wait until the server hangs repeatedly, crashes, or simply cannot start services at startup.

Best practices for maintaining the stability of installations of Microsoft Windows NT 4.0 Server (including all versions of Small Business Server) state that the server should never have less than 20 percent of total partition size as available free space, especially on the boot/computer partition if they are the same drive (for example, drive C).

With more than 20 percent available free disk space, plan a long-term strategy for increasing the free space on the partition. This may include planning a migration or computer rebuild with a larger boot/computer partition, or otherwise increasing hard disk space resources. At this point problems may start to occur, many of which are random and can be hard to diagnose or troubleshoot.

With between 10 and 20 percent available free disk space, initiate temporary measures to ensure server stability by moving programs, data, or computer files (such as the paging file or temporary folders) and eliminating or reducing file fragmentation.

With less than 10 percent free disk space, carry out emergency disaster prevention actions and recovery preparation techniques on the server immediately. This is especially critical if the action indicated is due in part to an absence of or lack of adherence to a previously developed maintenance plan or disaster prevention preparation program. With less than 10 percent available partition free space, problems increase in frequency and severity to the point that they may compromise the stability of the server and data loss and/or total loss of the server may be a real possibility.

With less than 5 percent free disk space, the computer could reach an unrecoverable state and special attention to loss prevention and computer backup of mission critical data should be a primary objective. In the case of a final effort to recover an already crashed server (deleting non-critical or temporary files, programs, or data that is saved on tape), sufficient free space must exist for a file fragmentation program to run.

Do not attempt to install a defragmentation program on a drive with less than 5 percent free space. In this state (the defragmentation program is not already installed), the options available include:

Boot to a parallel installation of Windows NT 4.0 in which the program has been installed, and run it from there.
Run the program from another server on the network if a network version is installed and the Small Business Server server network connection is functional.
Install the program on an existing drive or partition with sufficient free space, or add a new disk on which it can be installed.
As a last resort only, remove the drive and place it in another Windows NT 4.0 Server-based computer on which the defragmentation program is installed and run it from there. Observe safety practices such as completely shutting down the computer and turning off or unplugging the power source before any hardware changes are made.

WARNING: Especially with SCSI drives, take the drive with the existing controller and cables attached to the drive to eliminate changes in drive geometry and translation that can cause data corruption and/or data loss when drives are moved between different controllers or SCSI bus types.

Small Business Server 4.0 to 4.5 Upgrades

If the Small Business Server server has never been defragmented, and it has more than 10 percent of the total partition size as available free space, removing files from the Temp folder and Microsoft Internet Explorer cache and then running a file defragmentation utility may significantly stabilize the computer and reduce backup and file transfer problems.

If the Small Business Server server has not yet been upgraded to Small Business Server 4.5, consider an upgrade as part of a rebuild strategy. This provides a "fresh start" to architecture design (especially items relating to partition sizing and layout). Hardware upgrades can often be implemented as part of a rebuild and migration plan with little if any incremental downtime.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

228980 Upgrading from Small Business Server 4.0 to Small Business Server 4.5 when migrating from one computer to another