Re: Suggest Hardware Raid Controller Card

["Christopher Chan" <christopher.chan@xxxxxxxxxxxxxxx>]

----- Original Message ----- 
From: "John R Pierce" <pierce@xxxxxxxxxxxx>
To: <centos@xxxxxxxxxx>
Sent: Tuesday, July 12, 2011 8:34 AM
Subject: Re:  Suggest Hardware Raid Controller Card


> On 07/11/11 5:16 PM, Christopher Chan wrote:
>> Who needs bbu when you can get an SSD to work with your ext3/ext4 that is
>> sitting on an md raid 1/0/nested 1+0/10?
>
> lI hope your SSD isn't write buffering on commits.     many (most?)
> consumer priced SSDs can corrupt file systems badly on power failures
> during active file allocation operations, and drop pending database
> writes on the floor.
>
> If an SSD doesn't do write buffering, its brutally slow relative to its
> read speeds.  Only the more expensive enterprise drives have 'supercap'
> or other power backups for emergency buffer flushing in case of abrupt
> power shutdowns.
>

Wait, wait. So using SSDs as FAST writing disks is a load of hogwash? You 
still need stuff like umem nvram cards? What's the deal with things like 
Fusion IO then? 

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