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Posted to user@cassandra.apache.org by David Tinker <da...@gmail.com> on 2013/11/16 15:12:59 UTC
Commit log on USB flash disk?
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
Re: Commit log on USB flash disk?
Posted by David Tinker <da...@gmail.com>.
Not using a commit log at all isn't something I had considered. We may
very well be able to do that for our application. Thanks.
On Sat, Nov 16, 2013 at 6:17 PM, Tupshin Harper <tu...@tupshin.com> wrote:
> It's conceivable that one of the faster USB 3.0 sticks would be sufficient
> for this. I wouldn't exactly call it an "enterprise" configuration, but it's
> worth considering. Keep in mind that if you are comfortable using your RF
> for durability, you can turn off durable_writes on your keyspace and not
> write to the commitlog at all.
>
>
>
> On Sat, Nov 16, 2013 at 11:05 AM, Philippe <wa...@gmail.com> wrote:
>>
>> Hi david, we tried it two years ago and the performance of the USB stick
>> was so dismal we stopped.
>> Cheers
>>
>> Le 16 nov. 2013 15:13, "David Tinker" <da...@gmail.com> a écrit :
>>
>>> 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
>
>
--
http://qdb.io/ Persistent Message Queues With Replay and #RabbitMQ Integration
Re: Commit log on USB flash disk?
Posted by Tupshin Harper <tu...@tupshin.com>.
It's conceivable that one of the faster USB 3.0 sticks would be sufficient
for this. I wouldn't exactly call it an "enterprise" configuration, but
it's worth considering. Keep in mind that if you are comfortable using your
RF for durability, you can turn off durable_writes on your keyspace and not
write to the commitlog at all.
On Sat, Nov 16, 2013 at 11:05 AM, Philippe <wa...@gmail.com> wrote:
> Hi david, we tried it two years ago and the performance of the USB stick
> was so dismal we stopped.
> Cheers
> Le 16 nov. 2013 15:13, "David Tinker" <da...@gmail.com> a écrit :
>
> 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
>>
>
Re: Commit log on USB flash disk?
Posted by Philippe <wa...@gmail.com>.
Hi david, we tried it two years ago and the performance of the USB stick
was so dismal we stopped.
Cheers
Le 16 nov. 2013 15:13, "David Tinker" <da...@gmail.com> a écrit :
> 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
>
Re: Commit log on USB flash disk?
Posted by David Tinker <da...@gmail.com>.
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 <da...@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 <da...@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
>
>
--
http://qdb.io/ Persistent Message Queues With Replay and #RabbitMQ Integration
Re: Commit log on USB flash disk?
Posted by Mohit Anchlia <mo...@gmail.com>.
In our testing USB tends to be slower. If there is something more integrated internally would give you better performance
Sent from my iPhone
On Nov 16, 2013, at 8:30 AM, Dan Simpson <da...@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 <da...@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
>
Re: Commit log on USB flash disk?
Posted by Dan Simpson <da...@gmail.com>.
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 <da...@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
>