Re: [squid-users] HDD Configuration Recommendations

On Fri, 26 Sep 2008 17:52:13 +1200
Amos Jeffries <squid3_at_treenet.co.nz> wrote:

> Matus UHLAR - fantomas wrote:
> >> John Doe ha scritto:
> >>> two disks = RAID 0 or 1
> >>>
> >>> RAID 1 is mirroring:
> >>> - Pros: safe (goes on even with a dead HD), fast reads (from both disks)
> >>> - Cons: you only use 50% of total HD space (500GB total in your case).
> >>>
> >>> RAID 0 is stripping:
> >>> - Pros: fast reads/writes and you use 100% of total HD (1TB)
> >>> - Cons: unsafe (you lose 1 HD, you lose everything).
> >>>
> >>> Or just don't use RAID and create a cache_dir on each HD...
> >>> Best would be RAID1 for the system and no RAID for the cache_dirs I think.
> >
> > On 25.09.08 11:39, Marcello Romani wrote:
> >> I would add that a dead or malfunctioning drive could harm service
> >> uptime if the caache dirs are not on raid1.
> >> Therefore I would suggest keeping everything on raid1.
>
> The three setups which are usable with Squid and RAID are:
>
> RAID 1 + singe cache_dir - handles HDD failure silently. At cost of half
> the disk space. Q: is your cache big enough or bandwidth important
> enough to warrant saving the cache data?
>
> no-RAID + multi cache_dir - Twice the cache space. At cost of Squid goes
> down with either HDD. BUT, can be manually restarted without that
> cache_dir immediately on detection.
>
> RAID 0 + single cache_dir - already been covered. Generally considered
> worse than no RAID.

Depending on the expected load on squid, running with few users on a fast
SAS / SCSI (probably not SATA though) RAID 5 array is perfectly fine too.
Caveat emptor : I do not run an ISP :)

My own advice is, if you need squid to be fast, multiple cache_dir on
separate drives is the way to go. If you need uptime, you have to use
either RAID1 or RAID5 for those cache_dirs. If you need uptime and have
a limited number of users, a single cache_dir on a RAID5 partition is OK.
If you need speed and uptime, maybe multiple cache_dirs on multiple RAID1s
would work, but I never went that route.

Evaluate your load (number of users, speed of connections to users, speed
of Internet connection), your needs (speed / uptime), build for uptime and
see if it handles the load.

François
Received on Fri Sep 26 2008 - 08:28:23 MDT