[技術討論] 睇完個post之後唔敢再用qBittorrent

話說今日身痕想download Qbittorrent黎用,但睇到佢Official Forum個post之後都係決定用返uTorrent
Does qBittorrent use ram cache as uTorrent to protect harddisk?

大概係話qBittorrent(或其他libtorrent base的BT software)個disk write cache只係當HDD讀寫頻繁嘅時候用來作緩衝,對本身寫入嘅次數同碎塊並沒有幫助(即係佢cache完都係會用16-64KB嘅Blocks逐次將download咗嘅野亂數寫落HDD)
qBitTorrent uses much smaller 16-64 KB writes, which is terrible for SSDs and even bad for HDDs that are using a journaling system that doesn't support write-in-place.
The cache is there to store the active 16kiB 'blocks' of data that are used for transfers between peers. It does NOT store 'pieces' OR entire 'files' before writing to disc.


而utorrent就會完成咗一個完整嘅區塊(1 piece)先會一次過寫入HDD。(1 piece有幾大,個個torrent都唔同,細至64KB,大至16MB+都有)
uTorrent caches entire pieces and writes completed pieces to the HDD in 1 pass.


雖然BT點都會對硬碟有損耗,但似乎用utorrent點都會長命D (尤其是用SSD黎BT)
其他BT軟件我唔知,但qBitTorrent同Deluge就真係可以blacklist咗先,
大家點睇?

話說今日身痕想download Qbittorrent黎用,但睇到佢Official Forum個post之後都係決定用返uTorrent  ...
Kennn 發表於 2017-2-25 07:36


   
rTorrent都係基於libtorrent
我個Linux server 24小時運行Deluge, rTorrent都未出現問題,一個月至少讀寫15TB Data

via HKEPC Ionic Reader v1.6.0 - iPhone

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仲用緊 BITCOMET ,貪佢可以 SET 幾 GB CACHE
雖然大部份都係 READ CACHE 黎

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本帖最後由 GbE 於 2017-2-25 10:40 編輯

BT 本身都係亂序,唔會話你儲埋 10MB write 1 次,或 2MB write 5 次,個 WA 細或大好多. 另外宜家 d SSD 亦越來越聰明,background 做咗好多嘢。所有呢d軟件出咗咁耐,分別唔會大。除非有好多 RAM 可 cache 全部 file, 否則唔覺有冇分別,就算 cache 晒,最終都係要 write 落 SSD.

https://en.wikipedia.org/wiki/Libtorrent#Disk_caching

Similarly, for write requests, blocks are cached and flushed to disk once one full piece is complete or the piece is the least recently updated one when more cache space is needed. The cache dynamically allocates space between the write and read cache. The write cache is strictly prioritized over the read cache.

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咁Qbittorrent有乜優點??

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本帖最後由 GbE 於 2017-2-25 12:13 編輯

似乎就算每 piece 即 write, SSD 都未必有問題。
http://codecapsule.com/2014/02/1 ... -translation-layer/

The most common is the log-block mapping, which uses an approach similar to log-structured file systems.

Never write less than a page
Avoid writing chunks of data that are below the size of a NAND-flash page to minimize write amplification and prevent read-modify-write operations. The largest size for a page at the moment is 16 KB, therefore it is the value that should be used by default. This size depends on the SSD models and you may need to increase it in the future as SSDs improve.

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我都用緊qbittorrent down BT, 但係就down落個廢嘅160GB hdd. B死咗佢先算

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你講呢D的讀寫,本身HDD同SSD就有CACHE 去做呢件事
(三星等TLC SSD 除左RAM仲有SLC 做CACHE)

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回覆 6# GbE
幾乎全部SSD嘅Page Size都係4KiB,因為要跟返NTFS個預設叢集大細。

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回覆 5# Frozen
開放源碼、自由、穩定、功能和介面同uTorrent非常相近。

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