We are trying some experiments on our linux raid. We are having
bottleneck in scaling the RAID after ~250K IOPS. Is there a known
issue of s/w max limit or is it simply an issue of configuration?
We have (16 x 64G) SSDs on a RAID0. Our IOPS on this RAID0 stops at
250K (even with lesser or more SSD drives). Whereas we get 540K
IOPS with the same number of SSDs (RAW no RAID). We find a linear
scale-up for each SSD we add to RAID0 until we reach ~250K IOPS
limit. After the RAID0 reaches this limit, its just a straight line
plateau with no increase in performance.
Is there any known issue of the maximum IOPS the s/w can handle?
Cheers,
Arun
On Mon, Nov 30, 2009 at 6:24 PM, Arun Jagatheesan
[off-list ref] wrote:
We are trying some experiments on our linux raid. We are having bottleneck
in scaling the RAID after ~250K IOPS. Is there a known issue of s/w max
limit or is it simply an issue of configuration?
We have (16 x 64G) SSDs on a RAID0. Our IOPS on this RAID0 stops at 250K
(even with lesser or more SSD drives). Whereas we get 540K IOPS with the
same number of SSDs (RAW no RAID). We find a linear scale-up for each SSD we
add to RAID0 until we reach ~250K IOPS limit. After the RAID0 reaches this
limit, its just a straight line plateau with no increase in performance.
What are the specs of the rest of the system, and was does top/vmstat look like?
-Dave
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Keep an eye on CPU and RAM utilization. You may be hitting a bottleneck there.
Have you tried changing the queue depth of each SSD?
This may be of interest to you: http://linux-raid.osdl.org/index.php/Performance
On Tue, Dec 1, 2009 at 5:24 AM, Arun Jagatheesan
[off-list ref] wrote:
We are trying some experiments on our linux raid. We are having bottleneck in scaling the RAID after ~250K IOPS. Is there a known issue of s/w max limit or is it simply an issue of configuration?
We have (16 x 64G) SSDs on a RAID0. Our IOPS on this RAID0 stops at 250K (even with lesser or more SSD drives). Whereas we get 540K IOPS with the same number of SSDs (RAW no RAID). We find a linear scale-up for each SSD we add to RAID0 until we reach ~250K IOPS limit. After the RAID0 reaches this limit, its just a straight line plateau with no increase in performance.
Is there any known issue of the maximum IOPS the s/w can handle?
Cheers,
Arun
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Majed B.
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