On Fri, 26 Sep 2008 17:52:13 +1200 Amos Jeffries <squid3@xxxxxxxxxxxxx> 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
