[PVE-User] Proxmox, iSCSI, Mirrored LVM?

Eneko Lacunza elacunza at binovo.es
Wed Dec 11 09:16:43 CET 2013


Hi Ric,

On 11/12/13 00:27, Ric Moore wrote:
> On 12/10/2013 04:01 AM, Eneko Lacunza wrote:
>> Hi,
>>
>> Some time ago I did some (non-extensive) tests and I didn't like what I
>> saw. It seemed LVM wouldn't warn when a RAID1 had a failed disk, LV
>> seemed to behave wrongly and so on.
>>
>> If your environment allows it, I recommend to use mdraid, even if your
>> have to do it on different PV LVs; although it'd be better to use
>> disk->md->lvm .
> This begs the question which is best? We acquired an older Dell server 
> and are using the built-in hardware raid server to manage/oversee the 
> drives. I'm thinking it's long in the tooth, since it hasn't been 
> updated since 2005. Would a software raid be better? Would that 
> improve the responsiveness of the Proxmox cluster on it? Thanks, Ric
>
Currently mdraid is not supported on Proxmox, but my experience says 
that it works quite well. The only caveheat I found is, just don't 
change a RAID1 mirror count (->crash). If you're using big disks, 
remember to activate bitmap to help recoveries :)

Also, if your Dell server RAID card has battery-backed cache, then it 
will give you better performance than mdraid. Otherwise, I like to know 
that with mdraid I can plug the drives on any other linux box to 
read/use the data on them :)

Finally, booting the server with a failed disk drive in a RAID-set could 
prove easier with hardware RAID than with mdraid.

Cheers
Eneko

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