On Fri, 2003-01-24 at 06:43, thing wrote: > Tinus Nijmeijers wrote: > > >I'm building a server that needs about 200G of harddisk space and the > >data has to be safe. If I need to replace a faulty hd and get downtime > >that's fine. Speed is not an issue. > > > >The system will boot of a scsi HD, I have a backup boot disk available. > > > >Disks (couple of 120G IDE or something) will be in 1+0, raid5 or raid6 > >(does software raid do raid6?) > > > >Is there any reason to use hardware-raid over software-raid in this > >case? > > > > > >thanks. > > > >Tinus > > > > OK, For booting, I suggest getting a uw or better ie (u2w) scsi hardware > raid controller (AMI megatrends seem linux friendly) and 2 x 4gig ultra > wide (uw) or bigger disks (raid1 ~ mirrored), you dont need bigger, but > bigger disks will be younger and hopefully last longer. An improvement > would be 3 x 4 gig disks and have one as a hot spare to the first 2. I > wouldnt go older/smaller than 4 gig as 2 gig disks are getting very old > and are slower. This will be a robust boot system, software raid is not > any good for booting. > > Ive never heard of raid 6 (commercially anyway). > > Since speed is not your issue I suggest Raid 5 using software raid for > the data. Ive found it no worse performance wise than hardware raid (on > ide anyway) and way cheaper. Ive pulled a disk out of a software raid 5 > setup and re-inserted it and the system recovered fine (that was scsi > mind). These days CPU's are not usually the bottleneck in server > performamce so the penalty of the raid 5 calculations on the CPU seems > insignificant. > > Raid 5 needs at least 3 disks, as one disk is lost on parity, so your > options for 200 gig are 3 x 100 or 120 gig drives giving you 200 ~ > 240gig of usuable space or 4 x 80 gig disks also giving you 240gig of > raid 5. > > 3 disks is good as then if you so choose you can add an extra disk as a > hot spare, this way if one dies you rebuild on line and swap the dead > one out at your convienience. That means paying for an extra disk mind.... > > If you want to improve performance only put 1 ide disk per channel, this > means an extra ide controller (ie 2, assuming 2 channels per > controller), but there should be a speed improvement. > > regards > > Thing
My question kind'a stands: If the only thing I ask of it is for the data to be safe (no speed or "no downtime!" issues) is there any reason to use hardware over software raid? I do not care if I have to take the server down for an hour (or 2, or 3) to replace a disk, be it a raid disk or boot disk. I have plenty of time, I could even run down to the store, get a new bootdisk, install debian and be up and running in 2 hours. no problem. ONLY thing that is important is that the data needs to be safe. if 2 of the raid-disks fail I need the data to be safe. (it is, of course, a budget thing. In case of fire I have tapes to get the data back, there's downtime involved there. So I do care about downtime. Just that with disks being as cheap as they are I was thinking that a software raid is soooo cheap to build that maybe that's worth the extra cash for the 3 extra disks that I need to buy. scenario 1: boot of scsi, data is on a 200G IDE, tape backup scenario 2: boot of scsi, data on 4x80G IDE (software-raid5), tape backup = + EURO 100 scenario 3: boot of scsi, data on 4x80G IDE (hardware-raid5), tape backup = + EURO 500 scenario 4: boot of scsi, data on 4x80G SCSI (hardware-raid5), tape backup = + EURO 2200 so for close to nothing (E 100) extra I get software raid. Is hardware raid "safer"? (I do not think it is, I'm just waiting for someone to tell me I'm being naive here) Tinus. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
