SSDs can only read and write data a limited number of times. When an SSD drive has parts of a drive wear out, the drive becomes less efficient and fails to work well. This is due to the way traditional hard drives store data. When an old school mechanical drive deletes data, it simply marks that file as "deleted" and does not destroy that data until something new needs to be written. An SSD on the other hand actually has to erase data before it can write new data. This is slow due to the speed at which the erase rewrite command can take place and because if each particular block (unit of storage) is not full, the drive has to move the partially full chunk of data, erase the block, and then write the new data.
Over time, all of this writing and rewriting makes your SSD becomes a mess of broken up files. These files and the constant writes and rewrites lead to physical wear of the memory of the drive. The TRIM command moves the data around and prevents excessive wear to the drive and tries to prevent the file fragmentation and constant file movement to make new space. This is why it is important to know if your operating system and SSD support the TRIM command.
Thankfully if you are a Windows 7 user, you have TRIM built in and it should work automatically if your SSD supports the command. If you use any operating system previous to Windows 7, your SSD and system performance will degrade over time and it is recommended to upgrade to Windows 7. Macs are a different story...
If you are a Mac OS X user, you are out of luck. No versions of Snow Leopard support Trim unless you buy a new MacBook Pro that includes an SSD. Hopefully the next version of OS X (releasing this summer) will support TRIM for hard drive upgrades. If you are willing to risk it, there are unsupported patches to enable TRIM, but we advise against it unless your willing to risk your data. At this point, it seems prudent to wait on updating a Mac to an SSD until OS X Lion is released this summer.
Obviously this is far from a very technical explanation of TRIM and how SSD's operate. But, if you want to know more, check below for the related links.
- TUAW's Article:
- Verify TRIM Command is Active in Windows:
- Anthony's Take on SSD Drives:
- SSD Capacity Vs. Performance: