![]() TRIM is an essential part of keeping your SSD performance up (see this article for details) and it has been very beneficial for Windows 7 users. Another benefit of the TRIM command is that more space is available for dynamic OP.People are often concerned with the performance of their SSD is it running as fast as advertised. It also reduces the number of write cycles on the flash, increasing the SSDs endurance. With this information, the SSD no longer moves that invalid data during the GC process, eliminating wasted time rewriting invalid data to new flash pages. The SSD takes those addresses and updates its own internal map of its flash memory to mark those locations as invalid. Actually the TRIM command can be thought of as a message from the OS about what previously used addresses on the SSD are no longer holding valid data. It is not a command that forces the SSD to immediately erase data like some people believe. ![]() The SSD cannot tell what files have been deleted until the OS uses the same sectors to store new files, but by that time the SSD has already wasted cycles by garbage collecting data that was invalid, but known to the SS.ĭid you know HDDs do not have a Delete command? That is why SSDs need TRIMĪ number of years ago, the storage industry got together and developed a solution between the OS and the SSD by creating a new SATA command called TRIM. The TRIM command is sent by the OS to the SSD to identify what pages of data can be ignored during garbage collection. ![]() I talk about how TRIM came into existence and why it is necessary in my blog …. TRIM is beneficial to all SSDs regardless of what kind of garbage collection is used. Foreground GC is harder to achieve and I believe only the SandForce controller is able to do it today In simple terms background garbage collection will increase write amplification (WA) and wear out the SSD sooner. The difference between them is covered in my blog. Some use foreground GC and some use background or idle-time GC. The newly erased block of blank pages is then ready to save new data.Īll NAND Flash-based SSDs use GC. But first all surrounding pages with valid data must be read and then rewritten to blank pages. Random writes put the new data in previously erased pages elsewhere, peppering a block of valid data with “patches of invalid data.” In order to write new data to these patches, the whole block – all 128 pages – must be erased. The complexity of writing data really starts to escalate in the case of random writes replacing previously written data. But a page can only be erased within a group of typically 128 pages called a block. Once a page is written, it cannot be rewritten until it is erased. Trim can be considered an aid to garbage collection.įor the short explanation flash memory is organized in groups of pages where data can be written. OCZ SSDs use a Sandforce controller which has built in foreground garbage collection that delays the need to erase blocks, reducing but not removing the need for TRIM support. System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage.original $sudo cp /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage You can also enable trim manually by looking for all 'Apple' occurrences in the file and patching them in a hex-editor or via terminal: #1. Which checks if the ssd is a 3rd-party or Apple Branded SSD: The Trim Enabler patches the following Kext-File /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage
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