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From David Tinker <david.tin...@gmail.com>
Subject Re: Commit log on USB flash disk?
Date Sun, 17 Nov 2013 08:04:27 GMT
Hmm. That "device about to die" write latency signature is
interesting. I have pinged our hosting company asking for specifics as
to exactly what USB thumb drive they supply.

On Sat, Nov 16, 2013 at 6:30 PM, Dan Simpson <dan.simpson@gmail.com> wrote:
> It doesn't seem like a great idea.  The USB drives typically use dynamic
> wear leveling.  See this analysis on wear:
> https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CD8QFjAC&url=http%3A%2F%2Fwww.usenix.org%2Fevent%2Ffast10%2Ftech%2Ffull_papers%2Fboboila.pdf&ei=qZyHUrizFtKAygGs9YGoCg&usg=AFQjCNHTC7d6fcI1CNWmjbHMwgXI1nUWcQ&sig2=BaWgHj3ib-cQOBPQsoCadA&bvm=bv.56643336,d.aWc&cad=rjt
>
> If you you do end up using it, make sure to monitor write latency so you
> don't get hit by the bus.
>
>
> On Sat, Nov 16, 2013 at 6:12 AM, David Tinker <david.tinker@gmail.com>
> wrote:
>>
>> Our hosting provider has a cost effective server with 2 x 4TB disks
>> with a 16G (or 64G) USB thumb drive option. Would it make sense to put
>> the Cassandra commit log on the USB thumb disk and use RAID0 to use
>> both 4TB disks for data (and Ubuntu 12.04)?
>>
>> Anyone know how long USB flash disks last when use for a write heavy
>> workload like this?
>>
>> Please tell me if this is a really bad idea.
>>
>> Our alternative is to use one 4TB disk for commit log and one for
>> data. Of course this will give us only half the space.
>>
>> Thanks
>> David
>
>



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