M*d
2 楼
【 以下文字转载自 Programming 讨论区 】
发信人: MoonChild (df), 信区: Programming
标 题: 一般distributed system用什么consistency model
发信站: BBS 未名空间站 (Tue Apr 18 17:22:40 2017, 美东)
有两个server, 互为replica, 每个都和自己的backend talk, 但database 是同一个。
要求是要implement consistency＋in-memory cache, 具体哪种consistency 也不知道
。还要fault-tolerance
有什么思路呢多谢
发信人: MoonChild (df), 信区: Programming
标 题: 一般distributed system用什么consistency model
发信站: BBS 未名空间站 (Tue Apr 18 17:22:40 2017, 美东)
有两个server, 互为replica, 每个都和自己的backend talk, 但database 是同一个。
要求是要implement consistency＋in-memory cache, 具体哪种consistency 也不知道
。还要fault-tolerance
有什么思路呢多谢
g*4
3 楼
啊，人呢？
真是回荡绝顶啊！
真是回荡绝顶啊！
d*1
4 楼
包子
能pm一下是啥东西么
能pm一下是啥东西么
j*r
5 楼
两个同样前端结点，两个同样后端节点。数据库加个standby replica就差不多了。
【在 M*******d 的大作中提到】
: 【 以下文字转载自 Programming 讨论区 】
: 发信人: MoonChild (df), 信区: Programming
: 标 题: 一般distributed system用什么consistency model
: 发信站: BBS 未名空间站 (Tue Apr 18 17:22:40 2017, 美东)
: 有两个server, 互为replica, 每个都和自己的backend talk, 但database 是同一个。
: 要求是要implement consistency＋in-memory cache, 具体哪种consistency 也不知道
: 。还要fault-tolerance
: 有什么思路呢多谢
【在 M*******d 的大作中提到】
: 【 以下文字转载自 Programming 讨论区 】
: 发信人: MoonChild (df), 信区: Programming
: 标 题: 一般distributed system用什么consistency model
: 发信站: BBS 未名空间站 (Tue Apr 18 17:22:40 2017, 美东)
: 有两个server, 互为replica, 每个都和自己的backend talk, 但database 是同一个。
: 要求是要implement consistency＋in-memory cache, 具体哪种consistency 也不知道
: 。还要fault-tolerance
: 有什么思路呢多谢
G*s
6 楼
co-han, almost no position now, hope market gets 15%-18% correction
【在 g********4 的大作中提到】
: 啊，人呢？
: 真是回荡绝顶啊！
【在 g********4 的大作中提到】
: 啊，人呢？
: 真是回荡绝顶啊！
l*l
7 楼
pai
s*3
8 楼
既然同一个Db 因该没consistenct 的问题? 重点是如何fault tolerance?
【在 M*******d 的大作中提到】
: 【 以下文字转载自 Programming 讨论区 】
: 发信人: MoonChild (df), 信区: Programming
: 标 题: 一般distributed system用什么consistency model
: 发信站: BBS 未名空间站 (Tue Apr 18 17:22:40 2017, 美东)
: 有两个server, 互为replica, 每个都和自己的backend talk, 但database 是同一个。
: 要求是要implement consistency＋in-memory cache, 具体哪种consistency 也不知道
: 。还要fault-tolerance
: 有什么思路呢多谢
s*r
9 楼
co-han, hope we see it next week
r*u
10 楼
要return得
又不是送给你
【在 L****s 的大作中提到】
: 买了个600刀的东西，收到之后发现盒子烂的不成样子了
: 打了个电话complain了一下，不到一个小时就收到了fully refund
又不是送给你
【在 L****s 的大作中提到】
: 买了个600刀的东西，收到之后发现盒子烂的不成样子了
: 打了个电话complain了一下，不到一个小时就收到了fully refund
u*s
11 楼
你要fault tolerance基本上就要redundancy，这时候就要consistency了
【在 s****3 的大作中提到】
:
: 既然同一个Db 因该没consistenct 的问题? 重点是如何fault tolerance?
【在 s****3 的大作中提到】
:
: 既然同一个Db 因该没consistenct 的问题? 重点是如何fault tolerance?
Z*g
12 楼
舞台上只有你一人。。。
【在 g********4 的大作中提到】
: 啊，人呢？
: 真是回荡绝顶啊！
【在 g********4 的大作中提到】
: 啊，人呢？
: 真是回荡绝顶啊！
L*s
13 楼
在哪里看是否需要return？
【在 r*****u 的大作中提到】
: 要return得
: 又不是送给你
【在 r*****u 的大作中提到】
: 要return得
: 又不是送给你
k*i
14 楼
一般用 paxos
w*7
15 楼
顶
【在 g********4 的大作中提到】
: 啊，人呢？
: 真是回荡绝顶啊！
【在 g********4 的大作中提到】
: 啊，人呢？
: 真是回荡绝顶啊！
f*e
16 楼
你的良心
【在 L****s 的大作中提到】
: 在哪里看是否需要return？
【在 L****s 的大作中提到】
: 在哪里看是否需要return？
i*e
17 楼
你的问题不清楚。
你弄清：系统是用在什么地方，是否是地理上离很远，还是在同一个数据中心，是否两
个服务器是active active or active passive back up. Or whether there is a
primary replica and secondary replica, and replica management policy.
From request perspective, whether it's read intensive and/or write intensive
.
Once understood the above, then you can select consistency model/semantic.
1. Complete consistency. It means whenever a data item is updated, both
servers will be able to read this copy of data. In academic research, this
can be assumed. In reality, this is not achievable since it requests global
clock that does not exist in distributed systems.
2. Sequential consistency. This relaxed the requirement of global clock a
bit. It assumes predefined sequential order of operations. Different
operations may execute at different time intervals, but following the order.
If so, the consistency is guaranteed.
3. Linear consistency. Stringer than 2.
4. ...
5. Eventual consistency. This is widely used in production system. It
relaxed the time requirement to minutes. It means eventually different
copies of the data will be consistent. Pro. Easier to implement, for short
period of time different copies of the same data exist. Eventual consistency
is used by Azure, AWS, GCP etc.
For in memory cache,the key trade off is network overhead vs. freshness of
cache data.
Fault tolerance is much more complicated. Will address later if having time
later on.
你弄清：系统是用在什么地方，是否是地理上离很远，还是在同一个数据中心，是否两
个服务器是active active or active passive back up. Or whether there is a
primary replica and secondary replica, and replica management policy.
From request perspective, whether it's read intensive and/or write intensive
.
Once understood the above, then you can select consistency model/semantic.
1. Complete consistency. It means whenever a data item is updated, both
servers will be able to read this copy of data. In academic research, this
can be assumed. In reality, this is not achievable since it requests global
clock that does not exist in distributed systems.
2. Sequential consistency. This relaxed the requirement of global clock a
bit. It assumes predefined sequential order of operations. Different
operations may execute at different time intervals, but following the order.
If so, the consistency is guaranteed.
3. Linear consistency. Stringer than 2.
4. ...
5. Eventual consistency. This is widely used in production system. It
relaxed the time requirement to minutes. It means eventually different
copies of the data will be consistent. Pro. Easier to implement, for short
period of time different copies of the same data exist. Eventual consistency
is used by Azure, AWS, GCP etc.
For in memory cache,the key trade off is network overhead vs. freshness of
cache data.
Fault tolerance is much more complicated. Will address later if having time
later on.
m*l
18 楼
顶
c*e
19 楼
600刀的东西,用脑子想想好不好
【在 L****s 的大作中提到】
: 在哪里看是否需要return？
【在 L****s 的大作中提到】
: 在哪里看是否需要return？
M*d
20 楼
cache consistency 怎么保证呢？
【在 s****3 的大作中提到】
:
: 既然同一个Db 因该没consistenct 的问题? 重点是如何fault tolerance?
【在 s****3 的大作中提到】
:
: 既然同一个Db 因该没consistenct 的问题? 重点是如何fault tolerance?
w*a
21 楼
真以为送给你了？
【在 L****s 的大作中提到】
: 在哪里看是否需要return？
【在 L****s 的大作中提到】
: 在哪里看是否需要return？
M*d
22 楼
thanks a lot.
Actually it's a project for a distributed system course
I have no idea at all how to implement. The requirement is kinda vague as
well.
It just asks to implement all the concept.
The system is internet of things, where you have sensors/devices and a
gateway(controller) and a backend server(persistence layer)
I can think of a replica both for the gateway and backend, but I still have
to think about it.
intensive
global
【在 i*****e 的大作中提到】
: 你的问题不清楚。
: 你弄清：系统是用在什么地方，是否是地理上离很远，还是在同一个数据中心，是否两
: 个服务器是active active or active passive back up. Or whether there is a
: primary replica and secondary replica, and replica management policy.
: From request perspective, whether it's read intensive and/or write intensive
: .
: Once understood the above, then you can select consistency model/semantic.
: 1. Complete consistency. It means whenever a data item is updated, both
: servers will be able to read this copy of data. In academic research, this
: can be assumed. In reality, this is not achievable since it requests global
Actually it's a project for a distributed system course
I have no idea at all how to implement. The requirement is kinda vague as
well.
It just asks to implement all the concept.
The system is internet of things, where you have sensors/devices and a
gateway(controller) and a backend server(persistence layer)
I can think of a replica both for the gateway and backend, but I still have
to think about it.
intensive
global
【在 i*****e 的大作中提到】
: 你的问题不清楚。
: 你弄清：系统是用在什么地方，是否是地理上离很远，还是在同一个数据中心，是否两
: 个服务器是active active or active passive back up. Or whether there is a
: primary replica and secondary replica, and replica management policy.
: From request perspective, whether it's read intensive and/or write intensive
: .
: Once understood the above, then you can select consistency model/semantic.
: 1. Complete consistency. It means whenever a data item is updated, both
: servers will be able to read this copy of data. In academic research, this
: can be assumed. In reality, this is not achievable since it requests global
L*s
23 楼
Receiving a Refund
We'll request a refund after we receive and process your return. If you are
due a refund for non-returnable items, such as groceries, we'll issue a refu
nd when you contact us.
For items directed to our Returns Center, expect your refund within 4 weeks
of giving your package to the return shipper (though in many cases you'll re
ceive the refund sooner).
This time period includes:
* 5 to 10 business days for us to receive your return from the shipper
* 3 to 5 business days for us to process your return
* The time it takes your bank to process our refund request (see below f
or specific guidelines)
We'll notify you via e-mail of your refund once we've received and processed
the returned item.
You can view completed returns and refunds at the bottom of an order's summa
ry page in Your Account. If the return and refund do not appear in Your Acco
unt within 4 weeks from the day you sent us your return, please e-mail us fo
r help.
【在 w***a 的大作中提到】
: 真以为送给你了？
We'll request a refund after we receive and process your return. If you are
due a refund for non-returnable items, such as groceries, we'll issue a refu
nd when you contact us.
For items directed to our Returns Center, expect your refund within 4 weeks
of giving your package to the return shipper (though in many cases you'll re
ceive the refund sooner).
This time period includes:
* 5 to 10 business days for us to receive your return from the shipper
* 3 to 5 business days for us to process your return
* The time it takes your bank to process our refund request (see below f
or specific guidelines)
We'll notify you via e-mail of your refund once we've received and processed
the returned item.
You can view completed returns and refunds at the bottom of an order's summa
ry page in Your Account. If the return and refund do not appear in Your Acco
unt within 4 weeks from the day you sent us your return, please e-mail us fo
r help.
【在 w***a 的大作中提到】
: 真以为送给你了？
M*d
24 楼
能否具体说说
节点之间的consistency怎么保证
【在 j**********r 的大作中提到】
: 两个同样前端结点，两个同样后端节点。数据库加个standby replica就差不多了。
节点之间的consistency怎么保证
【在 j**********r 的大作中提到】
: 两个同样前端结点，两个同样后端节点。数据库加个standby replica就差不多了。
L*s
25 楼
这个才是需要return的流程吧
哪有还没收到return的东西就先退钱的...
are
refu
weeks
re
【在 L****s 的大作中提到】
: Receiving a Refund
: We'll request a refund after we receive and process your return. If you are
: due a refund for non-returnable items, such as groceries, we'll issue a refu
: nd when you contact us.
: For items directed to our Returns Center, expect your refund within 4 weeks
: of giving your package to the return shipper (though in many cases you'll re
: ceive the refund sooner).
: This time period includes:
: * 5 to 10 business days for us to receive your return from the shipper
: * 3 to 5 business days for us to process your return
哪有还没收到return的东西就先退钱的...
are
refu
weeks
re
【在 L****s 的大作中提到】
: Receiving a Refund
: We'll request a refund after we receive and process your return. If you are
: due a refund for non-returnable items, such as groceries, we'll issue a refu
: nd when you contact us.
: For items directed to our Returns Center, expect your refund within 4 weeks
: of giving your package to the return shipper (though in many cases you'll re
: ceive the refund sooner).
: This time period includes:
: * 5 to 10 business days for us to receive your return from the shipper
: * 3 to 5 business days for us to process your return
j*n
26 楼
Cache 一定要in server的memory吗？redis行不行
c*e
27 楼
贪心贪到英文都不认识了?
are
refu
weeks
re
【在 L****s 的大作中提到】
: Receiving a Refund
: We'll request a refund after we receive and process your return. If you are
: due a refund for non-returnable items, such as groceries, we'll issue a refu
: nd when you contact us.
: For items directed to our Returns Center, expect your refund within 4 weeks
: of giving your package to the return shipper (though in many cases you'll re
: ceive the refund sooner).
: This time period includes:
: * 5 to 10 business days for us to receive your return from the shipper
: * 3 to 5 business days for us to process your return
are
refu
weeks
re
【在 L****s 的大作中提到】
: Receiving a Refund
: We'll request a refund after we receive and process your return. If you are
: due a refund for non-returnable items, such as groceries, we'll issue a refu
: nd when you contact us.
: For items directed to our Returns Center, expect your refund within 4 weeks
: of giving your package to the return shipper (though in many cases you'll re
: ceive the refund sooner).
: This time period includes:
: * 5 to 10 business days for us to receive your return from the shipper
: * 3 to 5 business days for us to process your return
j*r
28 楼
两个节点用同一个数据库，哪里会有consistency 的问题。
单反前端只有两个节点的，RDBMS都足够了。整得更复杂的都是纸上谈兵的。
【在 M*******d 的大作中提到】
: 能否具体说说
: 节点之间的consistency怎么保证
单反前端只有两个节点的，RDBMS都足够了。整得更复杂的都是纸上谈兵的。
【在 M*******d 的大作中提到】
: 能否具体说说
: 节点之间的consistency怎么保证
L*s
29 楼
麻烦给解释一下？
真没看明白
【在 c*******e 的大作中提到】
: 贪心贪到英文都不认识了?
:
: are
: refu
: weeks
: re
真没看明白
【在 c*******e 的大作中提到】
: 贪心贪到英文都不认识了?
:
: are
: refu
: weeks
: re
m*s
30 楼
关键是invalidate对方的cache
【在 M*******d 的大作中提到】
: 能否具体说说
: 节点之间的consistency怎么保证
【在 M*******d 的大作中提到】
: 能否具体说说
: 节点之间的consistency怎么保证
c*e
31 楼
We'll request a refund after we receive and process your return.
【在 L****s 的大作中提到】
: 麻烦给解释一下？
: 真没看明白
【在 L****s 的大作中提到】
: 麻烦给解释一下？
: 真没看明白
L*s
32 楼
问题是我已经收到refund的钱了啊...
【在 c*******e 的大作中提到】
: We'll request a refund after we receive and process your return.
【在 c*******e 的大作中提到】
: We'll request a refund after we receive and process your return.
w*a
33 楼
你用的什么place的order？
就算你看见refund了，那也完全可以是temporary的
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
就算你看见refund了，那也完全可以是temporary的
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
l*i
34 楼
你是不是打算把东西留下，然后白吃AMZ600. 呵呵
贪小便宜的人往往吃大亏
贪小便宜的人往往吃大亏
f*j
35 楼
那还可以再charge你不是
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
c*7
36 楼
发包子就可以了
D*g
37 楼
pai
r*u
38 楼
收不到你的return
会重新charge你的cc
我就被charge过
当然你可以 close你的cc
【在 L****s 的大作中提到】
: 买了个600刀的东西，收到之后发现盒子烂的不成样子了
: 打了个电话complain了一下，不到一个小时就收到了fully refund
会重新charge你的cc
我就被charge过
当然你可以 close你的cc
【在 L****s 的大作中提到】
: 买了个600刀的东西，收到之后发现盒子烂的不成样子了
: 打了个电话complain了一下，不到一个小时就收到了fully refund
b*6
39 楼
先排包子
m*r
40 楼
如果是fba不知道哪个神医又要悲剧了
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
b*r
41 楼
人家相信你，先把钱给你，要是收不到货，会再把钱拿回去的。
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
【在 L****s 的大作中提到】
: 问题是我已经收到refund的钱了啊...
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