varnish on flash drives

Rob Tucker rob.g.tucker at
Sun Jan 20 04:17:01 CET 2008

The flash drive I have support 1M cycles so if I treat it as circular
buffer and keep writing to it, at my rate, it would last me more than
10 years.
So it is not a concern. So if I go ahead with this config, I wonder if
it would work out ok. i.e.
1) Can I choose a FIFO replacement policy that ensures writes happen
sequentially to the media.
2) Would randomly reading one object that is not in memory result in
more than 1 access on the underlying device. Objects I'm talking about
would rarely exceed 10KB.


>Flash Drives are bad for systems with a high io-load (Flash Drives
have poor write Performance and a limited count of write access).
> Get more Ram. You should be able to fit 32GB of ram in any Serversystem for a reasonable Price. To get a good harddisk IO Performance, get hardware raidcontroller an stripe a lot of small fast scsi-disks.

> Christoph

On Jan 19, 2008 1:14 PM, Rob Tucker <rob.g.tucker at> wrote:
> I'd like to run a reverse proxy on a machine with solid state drives. The hope is to get more queries served by utilizing high random I/O performance (the drive I have supports about 5K requests per second of average 4KB objects).
> I'll have 16GB of RAM, 128GB of flash, and tons of CPU on the machine. The entire 128GB of cache will be active in general.
> The question is whether I should run Varnish on this hardware. SSD random write performance is very poor, and I don't understand how Varnish replaces objects. LRU won't be friendly to SSD. FIFO would be good enough for my purpose. Is it possible to configure it that way?
> Also, when using the flash drive as a disk, would I be guaranteed to make exactly one read on the flash per object I fetch from it (for objects that don't reside in the memory)?
> Thanks.
> Rob

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