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From Amit Kumar <>
Subject Re: Use of SSD for commitlog
Date Wed, 08 Aug 2012 14:41:48 GMT

There is a really good presentation about SSD and Cassandra on youtube by Rick Branson. I
highly recommend watching it.

On Aug 8, 2012, at 6:23 AM, Hiller, Dean wrote:

> A 7.5 is probably fine and can still beat it as it is going to be the speed of writing
not seeking(and I am not sure if they spec hard drives with a write time when not seeking….not
sure).  Remember that drives are rated on how fast they spin…this disk should not be spinning
a lot(in theory)…it is always writing.
> Even on a read, it would do one seek and then do a very long sequential read(and I think
that only happens on startup anyways).
> Later,
> Dean
> From: Darvin Denmian <<>>
> Reply-To: "<>" <<>>
> Date: Wednesday, August 8, 2012 7:16 AM
> To: "<>" <<>>
> Subject: Re: Use of SSD for commitlog
> Thanks for your reply Dean,
> considering your reply.... maybe I use a 15k RPM SCSI Disk, I think it'll perform better
than a SSD disk.
> On Wed, Aug 8, 2012 at 10:01 AM, Hiller, Dean <<>>
> Probably not since it is sequential writes….(ie. Seek performance is the big hit and
if it is sequential it should not be seeking and is about just as fast as an SSD in theory).
 In practice, I have not measure the performance of one vs. the other though…that I always
the best way to go.(you could write a micro benchmark test with warmup writes and then stream
writes to and see how it does without cassandra).
> Dean
> From: Darvin Denmian <<><<>>>
> Reply-To: "<><<>>"
> Date: Tuesday, August 7, 2012 8:34 PM
> To: "<><<>>"
> Subject: Use of SSD for commitlog
> Hi,
> Can somebody tell me if is there some benefit in use SSD Disks
> for commitlog?
> THanks!

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