Tag Archives: hard

Backblaze 2015 年上半年的硬碟穩定度報告出爐了... (又黑了某公司一把)

Backblaze 這次丟出了 2015 年上半年的數據,標題雖然是寫 2015Q2,但文章裡有半年的統計資料:「Hard Drive Reliability Stats for Q2 2015」。

雖然都知道某公司的產品故障率偏高,但這樣是有仇嗎 XDDD

這是統計資料:

另外是 4TB 的歷史紀錄,右邊兩家的數字有點少啊,不過 45 顆硬碟壞一顆不就 2.x% 了嗎,這數字到底是怎麼出來的啊:

Etsy 用 SSD 的故事

EtsyLaurie Denness 對於 Etsy 使用各種品牌 SSD 的情況給出了他的經歷:「SSDs: A gift and a curse」。

重點在於開頭說的:

SSD firmware is buggy

可以看到當 SSD 配上 RAID controller 的時候,常常會需要找問題... (而且很難找)

Intel 的評價很不錯:

Okay, bad start, we’ve actually had no issues with Intel. This seems to be common across other companies we’ve spoken to.

OCZ 倒了,被 Toshiba 收購,而且 S.M.A.R.T. 資訊很差,很難預測什麼時候會掛掉 (有助於提前替換):

However, they had poor SMART info (none) so predicting failures was hard.

HP 是個大黑盒:

Unfortunately, HP have proprietary RAID controllers, and they don’t support SMART. Or rather, they refuse to talk to non-HP drives using off the shelf technology, they have their own methods.

Samsung 的評價不錯,C/P 值很高,而且有 S.M.A.R.T.:

Samsung saved the day and picked up from OCZ with a ludicrously cheap 960GB offering, the 840 EVO. A consumer drive, so very limited warranty, but for the price (~$400-500) you got great IOPS and they were reliable. They had better SMART info, and seemed to play nicely with our hardware.

不過 BB6Q 版的韌體搞爆了效能,雖然最後修好了:「Samsung Releases Firmware Update to Fix the SSD 840 EVO Read Performance Bug」。

LiteOn 則是掛在 GC 上 (RAID 裡同時掛掉兩顆以上):

The SSDs were having extended garbage collection periods, exacerbated by a smaller amount of SSDs with higher IO, in RAID6. This caused the controller to kick the drive out of the array… and unfortunately due to the write levelling across the drives, at least two of them were garbage collecting at the same time, destroying the array integrity.

不過後來 Dell 與 LiteOn 分別就 RAID controller 與 SSD 本身都跳下去修正,最後還是解決了:

Dell and LiteOn together identified and fixed weaknesses in their RAID controller, the backplane and the SSD firmware.

算是經驗分享,在 SSD 硬碟成熟的過程中間必經的道路 XD

Backblaze 的 3TB 硬碟故障分析

Backblaze 針對 3TB 硬碟繼續黑 Seagate... XDDD:「CSI: Backblaze – Dissecting 3TB Drive Failure」。

前面的數量比較不好懂,用百分比比較容易了解:

文章裡還討論了外接或內接的情況,最後猜測的結論是,Seagate 的這個 3TB 型號的品質特別差,因為 4TB 就正常許多:

While this particular 3TB model had a painfully high rate of failure, subsequent Seagate models such as their 4TB drive, model: ST4000DM000, are performing well with an annualized 2014 failure rate of just 2.6% as of December 31, 2014. These drives come with 3-year warranties and show no signs of hitting the wall.

Backblaze 用 SMART 的資料推算硬碟故障可能性

Backblaze 的「Hard Drive SMART Stats」這篇文章裡面提到了用 S.M.A.R.T. 的資料交叉分析硬碟存活的比率。

比較有趣的是對 Power_Cycle_Count 這個數據的解讀:

We’re not sure whether this is because cycling the power is bad for the drive, or because working on the pods is bad for the drives, or because “new” drives have flaws that are exposed during the first few dozen power cycles and then things settle down.

再對照其他幾張與 Power_Cycle_Count 相關的圖,通電次數看不出跟存活率有絕對關係 :p

各家硬碟的耐用程度...

最近幾天備份服務 Backblaze 以他們自家使用大量的硬碟統計數字 (快三萬顆硬碟),對硬碟耐用程度發了一篇「What Hard Drive Should I Buy?」的文章。

其實最重要的事情在第一張圖的年故障率就講的差不多了...

另外還有一張三年故障率存活率:

這數字在國外引起不小的風暴啊...