RAID Spanning using SSD and mechanical

[hairystuff]

Has anyone setup RAID Spanning using a SSD and mechanical hard disk, reason for asking is would it allow for data stored in the first part of the mirror (which would be the SSD) such as the OS to load rapidly over the additional stored data which would eventually end up on the mechanical hard disk, any input would be helpful.

 

[Wamphryi]

I have never heard of such a scenario and doubt that it is technically possible to achieve the somewhat muddled outcome you are describing.

 

[hairystuff]

How does spanning arrange the data out anyway, does it fill one drive in the chain then the others sequentially or does it equally spread the data across all the drives.

 

[Wamphryi]

Spanning is RAID 0. If the RAID Controller could deal with that set up the PC would write random data across the whole array. It would also write to both the SDD and the HDD simaltanously. Your SSD would slow to the speed of the HDD and your HDD would reflect the size of the SSD no doubt leading to a drop in capacity. Essentially you get the worst of both worlds. It spreads the data equally over both drives. If you are running out of room on your SSD and are thinking of giving it some headroom your idea simply wont work. Also when you add a drive to an array then it nukes the data on that drive.

 

[hairystuff]

Thanks for the info, the reason for throwing this idea about was to see if it was possible to make an economical hybrid storage system.

 

[mlarivie]

you could but it would require soft raid to be economical. In a Windows system this requires 7 Pro/Ult in Linux you can use LVM.

The scenario I see is that you want redundancy to boot the system in the event the SSD fails, but gain the performance benefits while it functions. - Using RAID 1 (mirror: Read from many, write and wait for all data to be written to each disk independently)

You can partition the disk to -160M (GBx1024 - 160 =MB) the size of the SSD for a system disk. Convert both the boot volume and SSD to dynamic and create a raid mirror. This will decrease the read cost (read from both) but increase the write cost (write-wait, write-acknowlege). Since its SSD there should be no noticeable write degradation. The rest of the disk can be mech-only and used for archives. Gaming, multimedia, etc all are read-intensive. There is really no demand for write performance unless you are transcoding blu ray movies or housing a database that is actively used.

It'll work great, go for it. I've been considering a cheap 32G SSD for my laptop for just that purpose.