Intel's release notes for Rapid Storage Technology (RST) 11.5 Alpha version reveal that they have plans to add TRIM support for RAID 0 arrays in the next version of RST. Windows 7 and Intel's RST have supported TRIM for quite a while, but the support has always excluded RAID 0 arrays. We don't know when the RST version with TRIM will arrive but given that the Alpha version dates back to August 5th, a newer version with TRIM should be expected sooner than later.

The benefits of TRIM are obvious because the write performance of an SSD will degrade in the long run without TRIM (or good garbage collection). Here is a quick brief on what TRIM is and what it does. TRIM is a simple command that allows the OS to inform the SSD controller what files are no longer in use (i.e. have been deleted). NAND flash doesn't allow individual pages to be erased; only a block can be erased. This causes problems because without TRIM, the OS just marks the deleted files as empty space, meaning that the actual data is not erased from the drive. When you run out of free blocks, you first have to read the whole block to cache before you can erase and then re-write the block. That means instead of a simple write, the SSD has to do a read, and erase, and then a write, which is why the write speed in degraded mode is much slower. For more detailed explanation on TRIM, take a look at our The SSD Anthology article.

For users who run SSDs in RAID 0, this is great news. While RAID 0 always introduces reliability concerns, the lack of TRIM is another obstacle for many. High capacity SSDs still cost a hefty premium, and putting two smaller SSDs in RAID 0 can save you a few bucks, plus you get increased read and write speeds.

Source: Intel via StorageReview

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  • inoshiro - Wednesday, January 25, 2012 - link

    Would you agree that TRIM cannot be used in the following situations:
    1. Server virtualization environment: For instance, we install VMware ESXi on a host, and a couple of virtual servers in it. Since TRIM works on deleted files, and files here are VMware virtual disks, the TRIM doesn't help when guest OS deletes files, until the whole virtual disk is deleted.

    2. SSD in a Database Server: Again the same, the data in databases is deleted, but the DB datafiles rarely. As long as no file is deleted, TRIM doesn't fire.

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