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HDD and SSD both on Raid-10
| Posted by HamidK, 10-23-2016, 11:18 AM |
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As we know that Raid-10 requires four hard drives, in which two of them are just for mirroring and can't be used.
Let us assume these four hard drives with Raid-10:
First Hard Drive: 500GB SSD
Second Hard Drive: 500GB SSD
Third Hard Drive: 500GB HDD
Forth Hard Drive: 500GB HDD
I would like to know, if we keep the third and forth hard drive HDD, would this effect the server's performance? Third and Forth are just for mirroring. Will it still effect performance or it won't effect much? The useable disk space is obviously only the first and second SSD.
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| Posted by TMS - JoseQ, 10-23-2016, 11:42 AM |
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Yes, it will affect performance greatly. Write ACKs will wait until data is written to both drives, they will not just continue while queueing up all pending writes. At some point the queue for the HDD will fill up and it'll be your bottleneck.
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| Posted by Pjflo, 10-23-2016, 12:53 PM |
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You would be restricted to the maximum speed of the slowest device (HDD).
There are various configurations you could use depending on your use case. The SSD's could be used for caching or for databases.
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| Posted by Srv24x7, 10-23-2016, 01:06 PM |
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Hi,
It is well known that the performance of SSD is better than HDD in many aspects, so it is not worth if you team it up with the HDD, as it will give you performance less than SSD but slightly better than HDD i.e., in the middle of both.
The disks will be attached and presented to you in the form of array, but the backend data will be replicated on both the disks simulateously and RAID will make sure that the data goes in properly everywhere it is configured to do so, but it will slow down the performance because of the performance capacity of the HDD being slightly lower than SSD.
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| Posted by alanwoo, 10-24-2016, 12:54 AM |
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In raid1setup, you can pair a SSD with a hdd, you can configure to primary read from SSD, this is where you get benefit of fast read speed, but you will have slower write speed, as it will need to wait for both SSD and HDD to complete the write cycle.
I not sure how to make this work in a raid10 setup.
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| Posted by SenseiSteve, 10-24-2016, 01:57 PM |
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I see where you're going with this, but in reality, the HDD's will slow the overall process down, adversely affecting performance.
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