On Fri, Jun 14, 2013 at 11:34 PM, Marcus Kool <Marcus.Kool@xxxxxxxxxxxxxxx> wrote: > Overall, squid servers without disk cache can be faster than with disk cache, > so it is worth looking at it. OVERALL, it either can be, or it cannot be. No two ways about it. OVERALL. >> > - more expensive (disks + battery-backed I/O controller) >> >> Expensive disks/battery-backed are over-kill. More/adequate spindles >> should do the job just as well. Why do you need a battery-backed >> controller? Squid is not a transaction-based system - if you lose the >> cache, tough, do "squid -z" and start again. > > fast disks are good. multiple controllers and mutiple buses are good. > An EMC disk array is the most expensive and best option since Squid desires > a huge number of IOPS. > Battery-backed disk controllers are a good tradeoff: they are not so expensive > and give a reasonable performance boost. You are missing the point completely. I'm not discussing the performance in relation to good/bad hardware, or EMC or IOPS or otherwise. I'm talking about how it relates to Internet access performance. If you have good hardware, but the bottleneck is somewhere else, you are barking up the wrong tree. >> > - Squid uses more memory to index the disk cache (14 MB memory per GB disk >> > cache) >> >> My memory allocation is only about 20-30% of that (formula), and >> paging/swapping metrics doesn't indicate there is a problem. General >> formulas may not always apply. > > The 14 MB per GB is documented in the Squid wiki and based on the > observation that the avergae object size is 13 KB. > If you only have 20-30% of the formula you may have a larger average > object size or only use 20-30% of the confgured disk cache. Yes, it may be documented. You forgot the IF's and MAY's. IF's and MAY's are very important. IF it applies to you, or it MAY apply to you, Try not to quote things without qualifications or understanding. > The thread started with a web proxy for an ISP. > ISPs generally do not want to restart the proxy and/or rebuild the index. > It takes too long. Don't assume. State the technical variables and let them decide. > No, memory is by far the fastest cache media. Since memory is > relatively cheap it is the best option. No, it's not when it doesn't solve the problem, if your bottleneck is somewhere else. > Ok, I stated it a bit aggressive. It should read > "Buy as much memory as your budget allows". Wrong. Don't buy more than what you actually need. > That is your point of view. I prefer to be careful not to use > more than enough since it wastes memory. I said the same thing. > Squid is hungry for a large number of IOPS. So get the best that > your budget can buy. > For low budgets this is a relatively cheap caching disk controller, > for high budgets it varies between low-end and high-end disk arrays > (the ones that have between 32 and 1000+ of spindles). Nothing to do with low or high budgets. Buy what will provide benefits in relation to cost.
