IO scheduler for SSDs on EC2?

2015-03-15 Thread Ali Akhtar 
I was watching a talk recently on Elasticsearch performance in EC2, and
they recommended setting the IO scheduler to noop for SSDs. Is that the
case for Cassandra as well, or is it recommended to keep the default
'deadline' scheduler for Cassandra?

Thanks.

Re: IO scheduler for SSDs on EC2?

2015-03-15 Thread Roni Balthazar 
Hi Ali,

The best practice is to use the noop scheduler on array of SSDs behind
your block device (Hardware RAID controller).
If you are using only one SSD disk, the deadline scheduler is the best
choice to reduce IO latency.
It is not recommended to set cfq on SSDs disks.

Regards,

Roni Balthazar

On 15 March 2015 at 09:03, Ali Akhtar ali.rac...@gmail.com wrote:
 I was watching a talk recently on Elasticsearch performance in EC2, and they
 recommended setting the IO scheduler to noop for SSDs. Is that the case for
 Cassandra as well, or is it recommended to keep the default 'deadline'
 scheduler for Cassandra?

 Thanks.

Re: IO scheduler for SSDs on EC2?

2015-03-15 Thread Dor Laor 
On Sun, Mar 15, 2015 at 2:03 PM, Ali Akhtar ali.rac...@gmail.com wrote:

 I was watching a talk recently on Elasticsearch performance in EC2, and
 they recommended setting the IO scheduler to noop for SSDs. Is that the
 case for Cassandra as well, or is it recommended to keep the default
 'deadline' scheduler for Cassandra?


In general the noop IO scheduler is the best suitable one for virtual
machines (regardless
of C* or SSDs). Usually the hypervisor below or the target SAN/NAS run
their own
IO scheduler so there is no need to do that twice.

From my own experience (managing the Xen and KVM dev teams @redhat) both
deadline and
noop gave similar results and were better than CFQ's.



 Thanks.