NAS建構試驗

Date: 04.05. 2023 

清明假期後段，把昔日淘汰電腦零件都搬出來，廢物利用的家用雲端NAS系統實驗

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挑六個2TB機械式硬碟，可以拼湊成一台網路儲存空間（NAS：Network Attached Storage)，Raid-5格式，可以容許一個硬碟掛掉，扣除一個硬碟容錯，有五個硬碟的資料量約10TB。主機板有支援M.2nvram SSD，改天在升級有快取空間，再加上兩個內部LAN2.5G網路卡，一個主機板原有的1TB網卡，可以當成家用雲端存放設備使用，家庭做實驗可以，實用性或可靠度而言，還是建議不要自己維護。去google或中華電信租個雲端空間，比較划算⋯⋯

RAID的原文為Redundant Array of Independent Disks，可翻獨立磁碟有多餘(中國翻成冗餘)陣列的架構，重點在Redundant（冗餘)。當指某個硬碟資料爛掉，影響資料的完整性及安全性，可以再搶救回來。NAS是比較簡單的網路存放方案，有幾個考量，首先是：1.某個硬碟爛掉了，要多久回覆時間？能夠爛掉幾顆硬碟？ 2.硬碟的空間存放的效率，冗餘是相對多與少的概念？ 3.存放系統的效能與負荷量。

During the latter part of the Qingming holiday, I brought out the old computer parts that had been discarded in the past for an experiment on home cloud NAS (Network Attached Storage) utilizing waste materials. 🧪⋯⋯ I selected six 2TB mechanical hard drives that can be assembled into a network storage space in RAID-5 format. This configuration can tolerate the failure of one hard drive, providing fault tolerance with a data capacity of approximately 10TB from the remaining five hard drives. The motherboard supports an M.2 NVRAM SSD, which can be upgraded in the future to include cache space. Additionally, I added two internal LAN 2.5G network cards to the existing 1TB network card on the motherboard. This setup can be used as a personal cloud storage device for home experiments. However, for practicality and reliability, it is recommended not to maintain it on your own. It would be more cost-effective to rent cloud storage space from providers like Google or Chunghwa Telecom. The term "RAID" stands for Redundant Array of Independent Disks, indicating an architecture of independent disks with redundancy. The emphasis is on redundancy. When a disk fails and affects data integrity and security, it can be recovered. NAS is a relatively simple network storage solution that involves several considerations. Firstly, if a disk fails, how long does it take for the system to recover? How many disks can be allowed to fail? Secondly, what is the efficiency of disk space utilization and redundancy? And finally, what is the system's performance and workload capacity?

我選用RAID-5系統，整個NAS系統至少3顆以上硬碟，總容量會少1顆容量？所以用5個硬碟架系統，只有4個硬碟空間的總容量（容量是80％效能），同時只容許爛掉1個硬碟，可以修復起來，如同時爛掉2顆硬碟，或是再修復硬碟前，又再爛掉1顆硬碟（1+1＝2），那資料也都完蛋了！

昨天睡前有個硬碟時數太高，系統警告硬碟將要爛掉且建議立即更換，以RAID-5自動修復，先現卸載1顆爛硬碟，換上新硬碟進行修復，需要修復時間是15小時之久，這修復期間，系統是處於低效能及不穩定期，最好不要用，去睡覺不要吵他！

I chose the RAID-5 system for my NAS setup. In this configuration, the NAS system requires a minimum of three or more hard drives, but the total capacity will be reduced by one drive. So, with five hard drives in the system, the total capacity will be that of four drives (capacity is at 80% efficiency). At the same time, it allows for the failure of one hard drive, which can be repaired. However, if two drives fail simultaneously or if another drive fails before the repair process is complete (1+1=2), then the data will be lost. Yesterday, before going to bed, I received a system warning indicating that one of the hard drives had accumulated too many hours of operation and was about to fail. The system suggested immediate replacement. Using the automatic repair feature of RAID-5, I first unloaded the failed drive and replaced it with a new one for the repair process. The repair time was estimated to be 15 hours. During this repair period, the system operates at lower efficiency and may be unstable. It is best not to use it and let it work without disturbance while sleeping.