Re: [squid-users] RAID is good

On Wed, Mar 26, 2008 at 3:30 PM, Marcus Kool
<marcus.kool@urlfilterdb.com> wrote:
>
> The point of why I started the discussion is that the statement in the wiki
> "Do not use RAID under any circumstances" is at least outdated.

Well, it says: "Don't". Agreed, it's a bit radical. You're welcome to
edit the wiki if you wish, just let me know your wiki username so that
I may give you write access.

> Most companies will trade in performance for reliability because they depend
> on internet access for their business and cannot afford to have 2-48 hours
> of unavailability.

I'm not going to argue with that. The point is that usually there are
more cost-effective ways to get the same level of reliability if not
more.
For instance, going JBOC (Just a Bunch Of Caches) with
load-balancing/high-availability mechanisms (Proxy PAC/WPAD or Linux
Virtual Server with or without VRRP or any other Layer 2-4 load
balancing solution) is a very effective system to get very high
reliability.

> Everybody knows that EMC and HP systems are much more expensive than
> a JBOD but this is not a valid reason to say "Never use RAID".
> "Never use RAID" implies that RAID is *BAD* which is simply not true.
>
> From my point of view, the wiki should say something like:
>
> If you want cheapest, modest performance, with no availability guarantees use JBOD.
> If you want cheap, modest performance and availability use RAID1/RIAD5 without
> a sophisticated disk array (preferably with a RAID card that has
> 128+ MB battery-backed write cache).
> If you want cheapest availability use RAID5 without a sophisticated disk array
> If you want expensive extreme performance and availability use a sophisticated disk array.

Agreed, it can be improved. The point that should be driven across is
that rather than spending 1kEur for a HW RAID SCSI Controller + 5KEur
for the disks to go with it, it's much more cost-effective to spend
2KEur for a second server and use VRRP.

-- 
 /kinkie