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I have a server with 6 SSD's and a raid controller card that supports both RAID 10 and RAID 50 the plan is to use this as our Build server. It will be pulling in NPM Packages and many small code files, compiling and uploading artefacts.

We currently have a server doing this and it is running up against an IO Bottleneck (it is using non SSD Drives currently in a RAID1 config).

Which RAID configuration would be best for this out of RAID 50 and RAID 10 for performance??

From the use case the IO will be mainly writes of small files (random writes). Disk Space and uptime are not a major concern as we have a failover and rebuilding the server is simple. So I am not concerned about how many drive failures before taking down the array etc the only consideration is performance.

RAID0 has been ruled out via bureaucracy.

I guess the real question is does the calculation for parity take longer than always writing to the same mirrored disk?

Paul Smith
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2 Answers2

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RAID 10 is the performance king, especially for writes. You will avoid parity calculations and write penalties.

https://www.xbyte.com/blog/post/testing-the-limits-of-the-dell-h710-raid-controller-with-ssd/

Bert
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  • Just to add, in order to get best performance you should choose enterprise grade SSDs, consumer grade SSDs performance can drop to HDD level at writes – Stuka Mar 07 '20 at 16:47
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Reads from an array are easy, one read off a data disk, no penalty.

RAID1 write penalty is 2, mirrored writes. RAID10 is also 2, the same thing striped across multiple RAID1 arrays.

RAID5 write penalty is 4, read and write both parity and data. RAID50 is also 4, striped across multiple RAID5.

Given the same set of physical disks, RAID5 IOPS will be worse than RAID1. A 10K RPM spindle might do 100 IOPS. Say 4 of them in an array is 400 raw IOPS. RAID5 might do 200 reads 50 writes, while RAID 10 might do 250 reads 75 writes. (Depending on the application's IO patterns.)

And then some consider single parity RAID5 too risky to use. Rebuilds can be hard on disks, and any two failures will kill a single parity array. Dual parity RAID6 is a thing, but imposes further costs of IOPS and capacity.

While spindles are bought to meet IOPS requirements, solid state generally tends to be sized for capacity.

If you can fit your storage on a single SSD, a RAID1 mirror is straightforward. Other array types are possible, especially since IOPS are less of limiting factor than they would be on spindles. In other words, the RAID6 write penalty may not be an issue for performance. But a mirror is very easy to operate.

John Mahowald
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