[英]Rackspace CDN TTL
I am using Rackspace ubuntu cloud servers and I'm also using Rackspace CDN images for my static web contents. 我正在使用Rackspace ubuntu云服务器,并且还将Rackspace CDN映像用于静态Web内容。 Sometimes I'll have to update some images/css in the CDN and they will not be reflected immediately.
有时我必须更新CDN中的某些图像/ css,它们不会立即反映出来。 The CDN has an option TTL from the range 1 to 72 in hours.
CDN的TTL选项在1到72小时之间。 I am failing to understand what the TTL is about and what TTL number suits me best.
我无法理解TTL的含义和最适合我的TTL编号。 Sometimes the URL of the CDN images change and when it happens?
有时CDN图像的URL会更改,何时发生? Anybody could help me please?
有人可以帮我吗?
The CDN TTL says for how long your copy will remain in the CDN after being copied from the main repository. CDN TTL表示从主存储库复制后,副本将在CDN中保留多长时间。 Selecting different values for TTL have several effects:
为TTL选择不同的值有以下几种效果:
cost since you get to pay for the copying from the main repository. 因为您需要支付从主存储库进行复制的费用。 I would assume a low TTL would increase costs.
我认为低TTL会增加成本。 I do not know if there is any charge to having data stored in the CDN.
我不知道将数据存储在CDN中是否要收费。
if you change a file while it is already in the CDN, that change may take up to TTL hours before it is available via the CDN to users. 如果在CDN中已存在文件的情况下对其进行更改,则该更改最多可能需要TTL小时才能通过CDN提供给用户。 A high TTL thus reduces flexibility.
因此,高TTL会降低灵活性。
speed/latency is also affected. 速度/延迟也会受到影响。 If the data requested by a user is not available in the CDN, it has to first be copied there from the repository which takes some extra time.
如果CDN中没有用户请求的数据,则必须先从存储库中将其复制到那里,这会花费一些时间。
In a project where the files where changing on average once a year or so I chose the maximum TTL of 72 hours. 在一个文件平均每年更改一次的项目中,我选择了72小时的最大TTL。
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