| Mapower MAP-TB32 Dual SATA RAID Enclosure
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Installation and Operation (continued):
SAFE-33 and SAFE-50 behave identically, but differ in the size of partitions constructed by the enclosure's controller. Both SAFE modes split each disk into two separate partitions, one of which is either 33 percent or 50 percent of the total space on the smaller of the two drives. It then constructs a RAID-1 volume from these partitions and a SPAN volume from the remaining partitions. For example, when choosing SAFE-33, two 300GB hard drives are each split into a 100GB partition and a 200GB partition. The two 100GB partitions are combined into a 100GB RAID-1 volume and the remaining 200GB partitions are combined into a 400GB JBOD volume. This gives you a reasonable compromise between the data mirroring of RAID-1 and the drive space of a SPAN volume. When I first read about the SAFE configurations I had hoped that the enclosure would use RAID-0 instead of SPAN, but benchmarks show this is not the case.
The different modes are selected via a system of jumpers on the enclosure's controller. Jumpers are a simple, effective, and inexpensive way to adjust configurations, but require good labeling. The image below shows the TB32CS jumper pins, and as you can see the information printed next to the pin header is vague. I would like to see Mapower either silk screen the different jumper configurations on the PCB next to the jumper pins or provide a label somewhere on the enclosure with the information. Currently the only source for this information is the manual, which if lost limits a user's ability to change modes.
The enclosure ships by default in the SPAN configuration. After installing the hard drives or reconfiguring the jumpers, the enclosure needs to be reset to initialize the desired mode. This is done by powering up the enclosure and depressing the small switch just to the right of the jumpers in the image above. In my review of this enclosure I needed to test every mode and occasionally found that it took multiple reset attempts to get the enclosure to initialize properly. Another issue I experienced during this phase was really more of a documentation problem than a hardware issue. When configuring the enclosure with a mode that utilizes RAID-1 (this includes the SAFE modes), it will begin a mirroring process that copies the contents of one partition or drive to the other. This operation can take an extremely long time if you have large hard drives or partitions. There will be a flashing LED on the front of the enclosure throughout this process. The enclosure is usable despite the mirroring process and flashing light, but the operation took several hours to complete with 250GB hard drives. It will be faster with the SAFE modes because they use smaller RAID-1 partitions. Mapower does mention the process will take place and that the length of time to completion is dependent on how much use the drive gets while the copying operation is in progress, but doesn't give you any idea that it can take hours. The manual provides documentation of the front LED behaviors and their meanings, but it is vague at best. I was unable to distinguish the difference between a flashing LED and a blinking LED, much less what the manual calls a Flashing LED that “will appear to be On”. I suspect most of the documentation issues are a function of language differences and could easily be remedied.
Once the enclosure is configured and initialized you need to connect it to your computer and begin the process of partitioning and formatting the volumes. This is accomplished in Windows via the Disk Management wizard. The manual briefly discusses this operation, but doesn't mention that with new hard drives, you may first need to initialize them in the Disk Management wizard in order to begin the partitioning and formatting process. This isn't difficult, but should be kept in mind.
There are a couple other items that need to be mentioned, First a reminder that while following the initialization procedure above you will lose any data on the disk, so make sure you back up your files before configuring the enclosure. Lastly, Mapower mentions only supporting Western Digital and Seagate disks. I can't say if other disks will work or not, but the fact that they specifically mention supported hard drives would lead me to believe there may be issues with drives from other manufacturers.
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