我的想法是這樣,60GB的一半跟120GB的一半哪個能有更大的空間讓控制晶片私下使用,60GB連OP1+OP2都一樣小一倍啊

下面這段就講得更清楚了
In theory, read speeds shouldn't be significantly impacted by the drive's free space. But there is a noticeable drop-off on the lower-capacity SF-22xx-based SSDs. Compression is one reason for this. Compressed data has to be decompressed, which requires sufficient free space. SandForce's garbage collection mechanism is a second explanation. Because most of its clean-up happens in the foreground, decompression requires a rotation of scratch space so that the NAND wears out evenly. This is known as wear leveling.


Both factors penalize the 60 GB drives we're rounding up more than the larger models as a result of limited NAND bandwidth, a side-effect of leaning on fewer NAND dies. We're using HD Tune to illustrate.

SERVER通常都會操到不能有時間跑GC

這時候SANDFORCE的價值就出來了

私下使用指的是什麼呢？這只是很單純的讀取測試啊......
難不成每次讀取需要預先解壓縮到其他空白區域？
這樣寫入放大率會變得多恐怖？每次讀取都需要寫入資料嗎？
Flash的壽命會減損很大吧

而且60GB算小容量？120GB算小容量？這個所謂大小如何評估呢？
多大對SF算夠大？剩多少空間給他用他才滿意？這似乎沒有標準
這個測試只用了這台SSD不到一半的容量而已啊

THG文章本身就這麼寫,我也相信是這樣,信不信就看人囉
In theory, read speeds shouldn't be significantly impacted by the drive's free space. But there is a noticeable drop-off on the lower-capacity SF-22xx-based SSDs. Compression is one reason for this. Compressed data has to be decompressed, which requires sufficient free space. SandForce's garbage collection mechanism is a second explanation. Because most of its clean-up happens in the foreground, decompression requires a rotation of scratch space so that the NAND wears out evenly. This is known as wear leveling.


Both factors penalize the 60 GB drives we're rounding up more than the larger models as a result of limited NAND bandwidth, a side-effect of leaning on fewer NAND dies. We're using HD Tune to illustrate.

這段的意思蠻奇怪的....SF光做讀取都需要額外的空間解壓縮？
這實在太傷Flash的壽命了吧

我們說一個2M壓縮成1M的檔案，SF雖然只寫入1M
但系統看到暫去的空間還是2M，只是有1M的Flash是空著的
假如他在讀取時，還需要一個另外2M的空間把他解壓縮出來放著再讀出來
這樣SF的SSD光做讀取就不斷的在耗損Flash的壽命了

反正寫進去的資料,我想各家控制晶片都會做某種程度上的挪移,不然某些部分被用到爆,某些部分被當成唯獨,很像也說不過去

在大陸的PCEVA有看過一篇文,當SSD讀取某些資料超過一定次數時,SSD要是沒幫資料換位置,資料的正確性可能會出錯(當然對壽命的影響沒寫入重)

那是為了要平均抹寫，會有挪動很合理
避免長期被某筆寫入一次資料只做讀取的區塊幾乎沒重複使用

可是就算需解壓再讀這一點為真，我們也不考慮Flash寫入耗損的問題好了
測試中的Intel 520SSD，顆粒的連續讀取應該可以到達450MB/s沒問題
測試中留了超過一半的空間給SF做任何他想要做的事情，足超過30GB
這樣的狀態SF的方案都無法滿足Flash顆粒本身的輸出流量？
那我買一顆SF 480GB的SSD要留多少空間做他想做的事情？300GB？

現在只好請手上有SF晶片的朋友出來跑一下hdTune現身說法了

240GB的系統碟,還是有掉一些些