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Server for virtualization - question about IO performance
Hi,
I am currently looking for a dedicated server to host a few VMs for private stuff.
The possible hard drive configurations are:
4x 1TB software raid 10 or
2x 1TB software raid 1 with an 128GB SSD for caching
CPU will be an E3-1230v3
Hardware raid is not an option since it is too expensive.
Which disk configuration will give me better IO performance?
Comments
How would you setup the caching ssd with soft raid/lvm?
Software RAID10 is your best bet, as you have more disks in that array (hopefully a lower chance of failure all in all, but you must make sure that you are actively paying attention to the SMART data and consistency of your array, since you have so few disks. Losing two of the wrong disks in a 4 disk RAID10 could mean total data loss, you can only lose one at a time.)
Frankly, the 128GB SSD won't do much for you, since you have no means to turn it into caching (You don't have the benefit of using CacheCade or some other caching software / hardware device at your budget level.)
If the VMs are OpenVZ, you can use Facebook's caching mechanism with the SSD, otherwise it's not much use to you unless you want it for your SWAP (which you still don't want failing ...)
2 x SSD for / (system)
2 x HDD for /vz (containers)
So, if some container is doing high IO, you can still manage the node as the system is running in SSD.
Not one of his options, he also didn't specifically specify that he was using OpenVZ.
Flashcache?
Why are we still pretending to live in 2000, it's perfectly possible with modern solutions like zraid(ZFS filesystem) or btrfs with caching.