[Babase] Question about file upload
Karl O. Pinc
kop at meme.com
Wed Mar 25 15:54:28 EDT 2009
On 03/25/2009 02:39:04 PM, Ryan Hardy wrote:
> On Mar 25, 2009, at 2:35 PM, Karl O. Pinc wrote:
>
>> Correct me if I'm wrong, but we would not _have_ to buy 2 73GB
>> drives. We _could_ buy 1 and have a mis-matched pair that
>> does not really take advantage of the faster new drive.
>> (It it probably a better use of Ryan's time if he does not
>> have to go search for a refurbished drive -- the small
>> amount of money saved could be worth the Ryan-goodwill-points.)
>
> Yes, you could do that as well. However, I have no experience
> running in that sort of setup and it is generally not recommended.
> That said, it would likely work, but it's possible that the
> algorithms that handle the devices are not optimized for that case
> and some performance degradation could happen. Solving that sort of
> problem, should it occur, would be painful at best and might result
> in just buying another drive at worst :)
I think we would just not solve the problem. I can't see
things being too much slower than the slower drive,
so we'd be no worse off than now.
> I believe the md device driver for raid1 setups has a fairly
> sophisticated load balancing algorithm for reads (writes are always
> done on both devices, of course), but I'm not too versed in the
> specifics. Honestly, I don't have a whole lot of experience at that
> level with software raid in general. The environments I've
> previously worked in have all used hardware raid setups.
The nice thing about software raid is that you don't have to
keep spare compatible controllers available to be assured
you have access to your data in the event of
controller failure. At least this used to be the
case. I've heard talk of some sort of industry standard
for raid, but I've no idea how far that has
progressed.
Karl <kop at meme.com>
Free Software: "You don't pay back, you pay forward."
-- Robert A. Heinlein
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