LSI RAID Controllers: Difference between revisions

=='''Older SAS controllers'''==

*ASUS PIKE 2008/IMR 8-port SAS2 6G RAID card

SAS2108 - DDR2 800Mhz, 8xSAS v2.0 3890MB/s, PCIe v2.0, PCIe 4x slot 1716MB/s, PCIe 8x slot 3433MB/s max throughput

'''LSI MegaRAID'''

*ASUS PIKE 2108 8-port SAS2 6G RAID card

'''LSI MegaRAID'''

*ASUS PIKE 2208 8-port SAS 6G HW RAID card

'''FEATURES'''

*X10SL7-F - 2x 4 port SAS internal 2x4 ports SAS, RAID 0, 1 and 10, no cache, no BBU

'''LSI MegaRAID'''

*Extreme11

'''LSI MegaRAID'''

*X9DRW-CTF31

*LSI SAS 9305-16e

*Supermicro AOM-S3216-L-2

*LSI SAS 9305-16i

*SuperMicro AOM-S3224-L

'''SAS3404''' PCIe 3.1, 12Gbs SAS,

*Fujitsu PRAID 680i

*LSI SAS 9600-8i8e

*LSI SAS 9670-24i

SAS1068, SAS2008, SAS2308 and (probably) SAS3008 have no cache hence the below does not apply

'''Read mode'''

The "Read mode" parameter can be used to influence cache behavior for read. A maximum of three options "No read ahead", "Read ahead" and "Adaptive" are available. No caching during read takes place in the case of "No read ahead". If a data block is requested, "Read ahead" causes further sequentially following data blocks to be already read from the hard disk to the cache of the controller just in case, and in the hope that they will be called for in subsequent requests. In the case of the "Adaptive" setting the controller itself attempts to determine whether a read-ahead makes sense or not.

'''Write mode'''

The setting options of the controller cache that control the handling of write requests are summarized under the term "Write mode". There are three options for setting the write cache: "Write-through", "Write-back" and "Always Write-back (independent of BBU state)". The "Write-through" option ensures that each write request from the controller is only reported back as completed when it has been acknowledged by the hard disk. With the "Write-back" and "Always Write-back" options the requests are cached in the controller cache and they are immediately acknowledged to the application as completed and only transferred to the hard disk later. This procedure enables optimal utilization of controller resources, faster succession of the write requests and therefore higher throughput. Any power failures can be bridged by means of an optional BBU, thus guaranteeing the integrity of the data in the controller cache. The "Always Write-back" option enables the write cache on a permanent basis; it is also used if the battery of the BBU is empty or if no BBU is installed, whereas the "Write-back" option automatically switches to "Write-through" as long as the controller cache is not battery-buffered.

'''Cache mode'''

The possible values here are "enabled" and "disabled". In most cases, the enabling of the hard disk cache entails an increase in throughput for write access. If the system is safeguarded by UPS, the enabling of the hard disk cache is recommended for performance reasons.

'''Batteries'''

'''MegaRAID LSIiBBU07'''

In the Box: MegaRAID LSIiBBU07, installation guide

'''MegaRAID LSIiBBU08'''

Part #: LSI00264

'''MegaRAID LSIiBBU09'''

Part #: LSI00279

'''Expanders'''

IBM ServeRAID Expansion Adapter 60Y0309

Astek A33606

'''Software/Hardware Feature Keys'''

ServeRAID M5000 Series Advance Feature Key 46M0930

ServeRAID M5000 Series Performance Accelerator Key 81Y4426

'''Alternate LSI SAS2xxx based controllers.'''

'''Areca''', a very good range of controllers, including up to 4GB of cache, they make  their own Firmware, not compatible with LSI MegaRAID.

'''3ware''', now owned by LSI, these controllers have their own firmware, not compatable with LSI's own MegaRAID range.