Simon Detheridge

Migrating large HDD to SSD on Megaraid, Drive Mixing Issues

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I've currently got a MegaRAID 9271-4i controller with a large Raid10 array of HDDs on it.

I'd like to upgrade it to an array of SSDs. The simplest way would seem to be to replace the drives in the raid one by one and allow it to reconstruct in between, but unfortunately my controller doesn't allow mixing of SSD and HDD drives in the same LD:

[root@ash-ketchum ~]# MegaCli -AdpAllInfo -a0 | grep -i mix
Allowed Mixing:
Mix in Enclosure Allowed
Mix of SAS/SATA of HDD type in VD Allowed
Allow Mixed Redundancy on Array : No
Allowed Device Type              : SAS/SATA Mix
Allow Mix in Enclosure           : Yes
Allow HDD SAS/SATA Mix in VD     : Yes
Allow SSD SAS/SATA Mix in VD     : No
Allow HDD/SSD Mix in VD          : No

This limits my options somewhat. There isn't enough physical space on the backplane to create a new array of SSDs and copy the data across. So, I'm thinking that my options are to:
a: build up a new computer with a new adapter and the SSDs, copy the data over a network and then take the SSDs out and put them in the other server, or
b: replace the RAID card in the server with one that supports mixed SSD/HDD in the same LD.
c: just destroy the array and create a new one, restore from backup

I would much prefer b as it would result in much less downtime - restoring from backup would take a long time as each VM stored on the array is backed up individually - but I can't find a product matrix (or similar) anywhere that tells me whether a card supports SSD/HDD mixing or not. I'm also unsure how compatible my foreign config would be between different brands of RAID card, or if I have to stick with Megaraid.

Anyone have experience of a Megaraid card that *does* allow SSD/HDD mixing in the same LD, or can offer any advice on other ways to accomplish my goal?

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If you want to laugh out loud at my reply, please do so. 

I don't know how much data you need to migrate:  without that knowledge, what I'm about to say may be totally in appropriate.

Several years ago, malware hit our SOHO network and "migrated" to every machine in that network.  It took 8 DAYS to re-build everything and disinfect every machine.

After that burn, we decided that THE BEST WAY to keep a PC virus-free is to TURN IT OFF!!  (lol here is aok :)

Whenever we have been faced with a similar challenge, we ALWAYS start with a FULL BACKUP of all data, including of course the operating system and all files and databases.  That FULL BACKUP is copied to one of our aging "backup servers" and then we turn that backup server OFF -- COMPLETELY OFF.

Because PC hardware is so cheap now, and because some data bases have become invaluable e.g. mirror images of a website, we do not hesitate to maintain cheap "white boxes" with aging CPUs that do very little except to XCOPY data from here to there.

We have even perfected a PUTT and GETT pair of Command Prompt BATCH files that do the job very well, particularly when we only need to backup a sub-folder in our website mirror.

Our consistent approach has also been to maintain a formal separation between C: system partitions, and all other partitions.

Every discrete storage device or RAID array is formatted with a primary partition exactly equal in size and contents to the Windows C: system partition.

The remainder of each such storage device is formatted with a Data partition e.g. D: or E: (in Windows parlance).

All of our key workstations host at leasat 2 identical copies of the same OS.

From experience, we know that it doesn't take too much to completely corrupt a working OS e.g. the other day, a HDD crashed and that crash ended up corrupting the Windows Registry.  So, with our dual-OS setup, we simply re-booted from the backup OS and restored a drive image of the primary C: partition:  piece o' cake.

As such, my first choice is your Option "A", making sure that you have a working "backup server" with redundant backups of all operating system and dedicated data partitions.

Trying to mix HDDs and SSDs sounds like too much work:  the future is solid-state, and I think you should migrate now to new system with SSDs and a quality / compatible RAID controller.  You can buy large HDDs for your backup server, the sole purpose of which is to archive multiple redundant copies of really important data.

Hope this helps. 

p.s.  I would be very interested to read more Comments from others who study your question.




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Here's how easy it is to build solid backup storage server.

I would recommend these parts:

Find a stock Intel heatsink/fan unit for the LGA775 socket,

remove the faulty push-pins, and use this backing plate instead:

Startech make a nice .5 meter SFF-8087 cable that works great with the RocketRAID 2720SGL:

leave the INT13 setting factory ENABLED if you plan to boot from this controller;

otherwise, install the card withOUT any drives attached (no cables),

then download and flash the BIOS to DISABLE INT13 after installing Windows.

The Intel D945 can be easily overclocked to 2 cores @ 4.0 GHz w/ SpeedStep, using:

240 MHz Front Side Bus

480 MHz DRAM clock, and that's why the G.SKILL DDR2-1066 is ideal, because it can exceed the JEDEC setting

normally limiting the speed of standard DDR2-800 DRAM.

The rest you already know how to do (I presume) e.g. power supply, chassis, etc.

One last thing, for our storage servers, we install the 2720SGL in the first x16 slot,

to ensure it gets max PCIe lanes assigned by these older chipsets.

Another option is to find a micro-ATX LGA775 motherboard with integrated graphics:

that will eliminate the cost of a video card e.g.:



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