Lesson 02 – Other Features of SSDs and RAID


TRIM Support and Garbage Cleanup

SSDs can suffer from speed degradation over time. The cause of the slow down is the time it takes for the SSD to delete no longer needed data before writing new data. This progressive slow down has largely been eliminated through the use of garbage collection mechanisms built into modern SSDs. These mechanisms actively look for unneeded data on the SSD and delete it before the SSD needs to write new data.

Another way to help with garbage collection is to look for an SSD that supports TRIM. Most drives currently on the market do support TRIM. TRIM is a command built into Windows 7 that works with the SSD to improve garbage cleanup.
SSD Firmware Updates

Firmware is the software that performs low level operations on the SSD. Updates to an SSD’s firmware can improve speed, reliability and available space on the drive.{reg} When you shop for an SSD make sure the drive you choose is supported by the manufacturer with firmware updates.
Types of RAID and their uses

You might consider using RAID with two of more SSDs. RAID allows you to connect two or more HDDs or SSDs together so they appear as one drive in Windows. There are three kinds of RAID Arrays. RAID 0, 1 and 5.

RAID 0 combines the capacity of 2 or more drives into one large array. The speeds are combined as well so if you have 2 SSDs and the SSDs can read and write at 500MBps individually in a RAID 0 array this doubles the speed to 1000MBps. 3 SSDs in RAID 0 would perform at 1500MBps.

RAID 1 uses 2 drives and keeps the same data on both drives. This gives you a built in backup at all times. If one drive fails the other keeps running allowing you to replace the failed drive and restore the array. When reading from the drives the speed is doubled because the data is the same on both drives and can be read back from both. Since the same data is written to both drives the write speed is not doubled.

RAID 5 combines the best aspects of RAID 0 and 1. 3 or more drives are combined with 1 third of the drives space used as redundant or parity data. If one of the drives fails it can be replaced with a new drive and the remaining data on the other 2 drives is used to recreate the missing data and get the RAID 5 array back to a fully working state with no data loss.

RAID 0 is most commonly used with SSDs. It gives the most speed and space out of your SSDs. Consider this. If a 128GB SSD costs $230 and gives you read and write speeds around 500MBps you can instead get 2, 64GB SSDs for $115, combine them in a RAID 0 array and double the read and write speed to 1000MBps.

Since you would have your operating system and main programs on the RAID 0 array you need a way to back up and restore them in case of a drive failure. We will show you how to do this using free programs provide by hard drive makers in Lesson 4.

As of summer 2011 only select Intel motherboards support TRIM on RAID. Though the support for TRIM in RAID will no doubt expand in the future, in the mean time you will need SSDs with very good garbage collection to maintain performance.

In Lesson 3 we will show how to enable SATA or RAID mode in the motherboards BIOS and if you opt to use RAID, how to enter the RAID configuration utility and configure the array. Since there are many types of BIOS and RAID configuration utilities we will show a variety.