RAID configuration for medium-sized file server

[Eshita The Techie]

I have read in an article that "If a server with high storage capacity will be established, it is useful to have a RAID 5 configuration to use. The use of three hard drives provides a useful capacity of two disks". I am not able to understand this.!? So posted here, so that I can get some help from you members, like always. I was looking out for RAID configuration for medium-sized file server in article and I found above quotes. Hope that you will provide some more information. Please.. I am waiting for your replies..

[Nurhan]

If a server with high storage capacity will be established, it is useful to have a RAID 5 configuration to use. The use of three hard drives provides a useful capacity of two disks.

The remaining space (parity data) is used to recover the data on a hard drive failure. NetWare, for example, usually needs a separate boot drive, since all system files are typically loaded at boot time and no need to load this normal during operation frequently. The three disks typically fit into a medium-sized server case with a belt drive and a CD/DVD-ROM. Since RAID 5, the replacement of a failed disk during operation support, a frame system for use with a separate active terminator for SCSI hard disks. The tape drive and the CD / DVD-ROM can be connected to either the RAID controller, or for better data throughput to a separate, low-SCSI adapter.

[Abraham.J]

More Usable capacity may be a file server and the operational phase will be added by using an "online expansion" of the RAID system is carried out. In order to achieve this, the mechanics, including electronics (corresponding storage backplane) already in the server may be present. The "Online expansion" of a RAID system integrates the new hard disk to the existing disk array, reorganizes the data and parity information and makes the additional storage for the operating system and therefore available to the user. One should interconnect with the online expansion, but do not overdo it and about too many disks into one large array. If you instead configure additional RAID arrays, it generally receives a better data throughput - even on the same controller. With about five drives in an array is obtained typically the best data throughput.

[Radames]

The standard RAID -5 configuration can be further enhanced by a 3-channel controller is used and each of the three hard disks -5 system to a separate SCSI channel is connected to the RAID. This allows the controller to address all disks simultaneously, making the system even faster. An additional advantage is that SCSI channels are now also redundant, so even if a complete SCSI channel fails (cable, connector or scheduling problems), lost only one hard disk redundant RAID-5 arrays.

[Elijah2010]

More security and better data throughput can be achieved by connecting the disks to a 3-channel controller. In this configuration, the disk array to each independent SCSI channels are connected. In the case of a cable defect, it can happen that two disks are lost, but because they belong to different RAID arrays, each array is available. To get even more security, an additional hard drive as a hot spare drive can be added, which then is available as a replacement drive, and immediately replace a failed drive. The RAID controller will start the repair of redundant arrays not instantaneous, so the system remains only for a very short period in a non-redundant state.

[Liliana]

If the replacement drive is defined as a pool of hot spare drive, they can both replace a failed drive in RAID 5 array and one of the two mirrored boot disks. In such a configuration is a 3-channel RAID controller, the optimal choice. Since only six drives are used, it is possible to accommodate them directly in the server chassis. Is this a problem, an external housing are used. In this case, the disks can still be distributed via the SCSI channels to the best possible redundancy and speed to get. In both configurations, it is advisable to use separate, active terminators for the SCSI bus. When 3-channel configuration, more capacity is needed at a, one can simply three more hard drives and add them to a new RAID 5 system interconnect. The operating system will see three logical drives, the boot drive (RAID 1), the data drive (RAID 5) and another data drive (RAID 5). If not enough space in the server, it must use an additional external housing. If it becomes necessary to remain the boot drive and the hot spare drive inside the server. In this configuration, the controller is no longer at the end of the SCSI bus and must not therefore be terminated.