LAN Server-Advanced consists of an SMB processor (386 SMB server) tightly coupled to a file system (the 386 HPFS). These components are designed and optimized for 386-compatible and above processors. LAN Server-Advanced provides an OS/2 file system driv er, running at system privilege, which requires minimal, if any, OS/2 services to satisfy network file I/O requests. Performance is enhanced by the use of Busmaster disk and network device drivers, which increase overlap of network and disk activity. LAN Server-Advanced uses read-ahead and write-behind logic, allowing network file I/O to occur at a rate that approaches network bandwidth when the data is fully cached or disk transfer rates when disk I/O is required.
The 386 HPFS provides access control information within each file. The access control information enables Local Security, provided with LAN Server-Advanced, to function consistently with remote access control. Local Security is the LAN Server component that allows a network administrator to secure the file system on the server workstation from local users. File I/O performance is enhanced because of a much larger cache capacity and more intelligent caching algorithms.
Server network buffers are passed to the server by the NETBIOS device driver. LAN Server-Advanced is optimized for 386 HPFS file I/O. Requests destined for non-HPFS resources such as the FAT file system, character devices, and named pipes are passed by LAN Server-Advanced to the Entry server, which is provided with LAN Server-Advanced. The requests are satisfied through OS/2 APIs.
The Advanced server processes the three typical file accesses much like the Entry server. The 386 HPFS file I/O requests may be sent with any of the three SMB protocol types discussed previously for the Entry server. For information on the Entry Server, see "LAN Server-Entry Design Overview" in topic 1.3. However, the Advanced server uses scatter/gather logic to enhance performance if it is supported by network and disk device drivers.
The following figure shows the components that may influence the performance of OS/2 LAN Servers (Advanced package) and OS/2 LAN Requesters. This figure also provides a reference for discussing individual performance-related elements.
System Architecture of the OS/2 Advanced Server and OS/2 LAN Requester
│
<─────────────Server────────────────────────>│<───────Requester─────────>
┌─────────────┐ │ ┌─────────────┐
│ Local │ │ │ Local │
│ application │ │ │ application │
└──────────┬──┘ │ └──────┬──────┘
┌────────────────────────┐ │ │ │
│ LAN Server 3.0 - Entry ├─────┐ │ │ │
├────────────┬───────────┤ │ │ │ │
│ Request │ Big │ ┌─┴─────┴──┐ │ ┌──────┴──────┐
│ buffers │ buffers │ │ OS/2 API │ │ │ OS/2 API │
└───┬────────┴───────────┘ └───┬──────┘ │ └──────┬──────┘
│ │ │ │ Application
│ │ │ │ privilege
────│────────────────────────────│───────────┼────────────│─────────────
│ │ │ │ System
│ │ │ │ privilege
│ ┌─────────────────────┴─┐ │ ┌──────┴──────┐
│ │ OS/2 kernel │ │ │ OS/2 kernel │
│ ├──────────┬────────────┤ │ ├─────────────┤
│ ┌─┤ IFS │ FAT │ │ │ IFS │
│ │ └──────┬───┴──────────┬─┘ │ └──────┬──────┘
┌───┴────┴──┐ │ │ │ ┌───────┴─────────┐
│ Redirector│ │ │ │ │ Redirector │
└─────┬─────┘ │ ┌────────┐ │ │ │ │
│ └──┤ File │ │ │ ├─────────┬───────┤
│ │ system │ │ │ │ Work │ Work │
│ │ driver │ │ │ │ buffers │ cache │
┌─────┴──────────┐ ├────────┤ │ │ └────┬────┴──┬────┘
│ LAN Server 3.0 ├───┤ 386 │ │ │ └──┬────┘
│ - Advanced │ │ HPFS │ │ │ │
│ SMB processor │ ├────────┤ │ │ │
├────────────────┤ │ HPFS │ │ │ │
│ Request buffers│ │ CACHE │ │ │ │
└─────┬──────────┘ └────┬───┘ │ │ │
┌─────┴──┐ ┌───┴──────┴┐ │ ┌──┴─────┐
│NETBIOS │ │Disk driver│ │ │NETBIOS │
│protocol│ ├───────────┤ │ │protocol│
│ driver │ │ DISKCACHE │ │ │ driver │
└───┬────┘ └────┬──────┘ │ └──┬─────┘
┌───┴───────────────┐ │ │ ┌────────┴──────────┐
│ Network adapter │ │ │ │ Network adapter │
│ driver │ │ │ │ driver │
├────────┬──────────┤ │ │ ├────────┬──────────┤
│Receive │ Transmit│ │ │ │Receive │ Transmit│
│buffers │ buffers │ │ │ │buffers │ buffers │
└────┬───┴────┬─────┘ │ │ └────┬───┴──┬───────┘
└───┬────┘ │ │ └───┬──┘ PS/2 Processor
─────────│─────────────────│─────────────────┼────────────│──────────────
┌──────┴────────┐ ┌──┴─────────┐ │ ┌────────┴──────────┐
│Network adapter│ │Disk adapter│ │ │ Network adapter │
│ card │ │ card │ │ │ card │
└───────────────┘ └────────────┘ │ └───────────────────┘
The next figure shows the components that may influence the performance of OS/2 LAN Servers (Advanced package) and DOS LAN Requesters. This figure also provides a reference for discussing individual performance-related elements.
System Architecture of the OS/2 Advanced Server and DOS LAN Requester
<─────────────Server────────────────────────>│<───────Requester─────────>
┌─────────────┐ │ ┌────────────┬───────────┐
│ Local │ │ │ Local │Application│
│ application │ │ │application │ memory │
└──────────┬──┘ │ └──────────┬─┴───────────┘
┌────────────────────────┐ │ │ │
│ LAN Server 3.0 - Entry ├─────┐ │ │ │
├────────────┬───────────┤ │ │ │ │
│ Request │ Big │ ┌─┴─────┴──┐ │ ┌──────┴──────┐
│ buffers │ buffers │ │ OS/2 API │ │ │ DOS API │
└───┬────────┴───────────┘ └───┬──────┘ │ └──────┬──────┘
│ │ │ │
│ Application privilege │ │ │
────│────────────────────────────│───────────┤ │
│ System privilege │ │ │
│ │ │ │
│ ┌─────────────────────┴─┐ │ │
│ │ OS/2 kernel │ │ Interrupt 2F
│ ├──────────┬────────────┤ │ │
│ ┌─┤ IFS │ FAT │ │ │
│ │ └──────┬───┴──────────┬─┘ │ │
┌───┴────┴──┐ │ │ │ ┌───────┴─────────┐
│ Redirector│ │ │ │ │ Redirector │
└─────┬─────┘ │ ┌────────┐ │ │ │ │
│ └──┤ File │ │ │ ├─────────┬───────┤
│ │ system │ │ │ │ Network │ Big │
│ │ driver │ │ │ │ buffers │buffers│
┌─────┴──────────┐ ├────────┤ │ │ └────┬────┴──┬────┘
│ LAN Server 3.0 ├───┤ 386 │ │ │ └──┬────┘
│ - Advanced │ │ HPFS │ │ │ │
│ SMB processor │ ├────────┤ │ │ Interrupt 5C
├────────────────┤ │ HPFS │ │ │ │
│ Request buffers│ │CACHE386│ │ │ │
└─────┬──────────┘ └────┬───┘ │ │ ┌──┴─────┐
┌─────┴──┐ ┌───┴──────┴┐ │ │ │
│NETBIOS │ │Disk driver│ │ │NETBIOS │
│protocol│ ├───────────┤ │ │protocol│
│ driver │ │ DISKCACHE │ │ │ driver │
└───┬────┘ └────┬──────┘ │ └──┬─────┘
┌───┴───────────────┐ │ │ ┌────────┴──────────┐
│ Network adapter │ │ │ │ Network adapter │
│ driver │ │ │ │ driver │
├────────┬──────────┤ │ │ ├────────┬──────────┤
│Receive │ Transmit│ │ │ │Receive │ Transmit│
│buffers │ buffers │ │ │ │buffers │ buffers │
└────┬───┴────┬─────┘ │ │ └────┬───┴──┬───────┘
└───┬────┘ │ │ └───┬──┘ PS/2 Processor
─────────│─────────────────│─────────────────┼────────────│──────────────
┌──────┴────────┐ ┌──┴─────────┐ │ ┌────────┴──────────┐
│Network adapter│ │Disk adapter│ │ │ Network adapter │
│ card │ │ card │ │ │ card │
└───────────────┘ └────────────┘ │ └───────────────────┘
Sideband Feature
Sideband is a set of enhancements designed to improve the performance of small random reads and writes to files on LAN Server 3.0. These enhancements are contained in the DOS LAN Requester and OS/2 LAN Requester components, the Advanced server components, and the latest release of the LAN Adapter and Protocol Support components.
If it is determined that an excessive number of frames are being lost on a single session, Sideband will be disabled for that particular session. Sideband will stay disabled until the session is ended. If the user would like to re-enable Sideband, the session can be deleted and restarted by disconnecting and then reconnecting all connections to the server in question.