Functions of the TFM configured for LSISAS 2208 RAID controller cards

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The TFM configured for LSISAS 2208 RAID controller cards is used to protect data in case of power failures. If this function is not required, you do not need to configure the TFM. LSISAS 2208 RAID controller cards will work properly without the TFM.
The working principles of the TFM are as follows:
During a power failure, data in the cache of an LSISAS 2208 RAID controller card is synchronized to the TFM, and supercapacitors are used to power the synchronization process. The TFM supports data recovery in various power failure scenarios.

Other related questions:
Memory function of RAID controller card
1. If the LSISAS2208/LSISAS3108 RAID controller card is configured with a battery or supercapacitor, data is written into the cache first. When the data volume in the cache reaches its limit, data is written into hard disks in sequence, greatly improving the access speed of small files. Cache is volatile storage. If it does not have a battery or supercapacitor, its data will be lost when the server is powered off. This may cause data inconsistency. For example, when a data record is written into the database, the RAID controller card stores the data record in cache first. However, at that time, the data record has not been written onto hard disks. If the server is powered off at that time, the data record will be lost and cannot be found in the database when required. The database keeps searching for the data endlessly. In extreme conditions, the database may crash. The battery or supercapacitor can prevent data loss in power failures. When a server is powered off unexpectedly, the batter or supercapacitor provides power to the RAID controller card. 2. If the LSISAS2208/LSISAS3108 RAID controller card does not have a battery or supercapacitor, data is directly written into hard disks.

Adding a disk to a RAID array
You can add a disk to a RAID array as follows: 1. If the LSISAS2208 or LSISAS3108 RAID controller card is used, you can add a new disk to a RAID array online. For details about how to expand the virtual disk (VD) capacity online, see HUAWEI Server RAID Controller Card User Guide 09. 2. If the LSISAS2308 or LSISAS3008 RAID controller card is used, you cannot add a disk to a RAID array through online capacity expansion and cannot expand the VD capacity online. 3. If softRAID is used, you cannot add a disk to a RAID array online or expand the VD capacity online.

Whether RAID 5 is supported by the LSISAS2208 RAID controller card
The LSISAS2208 RAID controller card supports RAID 5.

Method of configuring hot spares
After hard drives of a server are configured into RAID arrays, hot spares are usually configured to improve security and reduce the impact of hard disk faults on services.
For details about how to configure hot spares, visit the following link: http://support.huawei.com/enterprise/docinforeader.action?contentId=DOC1000004186&idPath=7919749|9856522|21782478|21149952|21152124

Configuring RAID card
Manuals: For details about how to configure the RAID card and precautions, see http://support.huawei.com/enterprise/en/doc/DOC1000004186?idPath=7919749|9856522|21782478|19955021|19961397. Videos: LSI SAS2208 RAID Controller Card Configuration http://support.huawei.com/huaweiconnect/enterprise/thread-243427.html LSI SAS2308 RAID Controller Card Configuration http://support.huawei.com/huaweiconnect/enterprise/thread-243441.html LSI SAS3008 RAID Controller Card Configuration http://support.huawei.com/huaweiconnect/enterprise/thread-281743.html LSI SAS3108 RAID Controller Card Configuration http://support.huawei.com/huaweiconnect/enterprise/thread-281765.html

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