Date: Thu, 22 Oct 1998 09:55:08 -1000 From: Terrance Young <tyoung@hmsa.com> To: Hallam Oaks <mlnn4@oaks.com.au> Cc: "freebsd-chat@FreeBSD.ORG" <freebsd-hackers@FreeBSD.ORG> Subject: Re: Multi-terabyte disk farm Message-ID: <362F8D9C.ACDA3BF0@hmsa.com> References: <199810221320.XAA07482@mail.aussie.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi... Hallam Oaks wrote: > G'Day; > > I've a few things I'd like, If I may, to get opinions on. ok... my opinions and semi-thoughts :-) below... <...Snip.. Ouch that was my fingers!..> > With current hard drive prices, I estimate we can put together a one > terabyte disk farm for about US$60k (cost of media only), spread across > several machines using hot swappable drive bays and dual SCSI buses per > machine. We don't intend to use RAID unless there's strong advantages to > it (I don't know a whole lot about it). We don't need striping or > replication. I think a Raid would serve you better in up time and reliabilty. RAID is a bit slower but has good error correction and fault tolerance. > > One advantage of doing it via a distributed farm (I theorise) is that if > one drive fries or one machine self-destructs, at least the rest of the > system will still be working. A fried drive can be restored from one of > the 25gb AIT backup tapes made of all the dubs. Humm.. Depends on how you do it I suppose... but if not raid on the data drives then at least mirroring on the OS drives.. and keep the data drives separate... (where's my coffee...) <...Snip! humm I seem to be losing fingers...> > > Needless to say I'm going to put my preferred solution as FreeBSD-based. > Some of the criteria that I can't yet answer and would like feedback on > are these - My Preferred choice ;-) > > o is FreeBSD able to be made to recognise a new SCSI drive that wasn't > present on boot ? i.e. a new drive is plugged into the hot bays. can > it be recognised, formatted, and mounted by manual intervention ? Sure! no prob... if you had a Hot Swap chassis... > o ditto if a drive fries. can it be taken out without the kernel getting > too upset ? Yup! as long as its in a hot swap chassis and not the OS mirrored drive hehe.. then I think you might have slight problems but it will come back up on the one good drive (how bad I'm not sure, hasn't happened to me yet *knocks on wood*).. > o is it feasable to automatically umount and spin down drives that > haven't been accessed for a day or so ? typically, the older data > (> 6 months) will be rarely, if ever, accessed before its two-year > span expires and it's erased. Humm...yup, you can spin it down when not accessing it when you use it again it might give you a timeout error which I think is sort of normal at least until the drive spins back up... > o would the boot time of a system be dramatically prolonged by it having > 500 or so gigabytes of SCSI drives hanging off its backside ? (I'm > referring to a normal boot, with the drives having been properly > unmounted. I don't even want to THINK about waiting on an fsck of 500 > gigs of unclean disk ;). OTOH the size of the files is quite large, so > it'd be feasable to use huge nodes. Yuck, Wash it :-) don't want to touch unclean disks hehe... But as to booting up a bit longer due to the amout of drives.. shouldn't be too unbearable... > I've no particular objection to a reboot if need be to add/remove a > drive, but if it took more than, say, 10 minutes, it'd be an issue I'd > have to tackle with management. Hehe... How fast can you change Disks? I think it would be at least a bit longer to powerdown, change drive and power up with 500 gigs...(go Hot Swap! less headaches and you don't need Pit Crew speed hehe...) > o we're thinking of using Seagate Elite 47gb drives. These are 5400 RPM > units (speed isn't an issue to us). Does anyone have any opinions > about these (good/bad/indifferent) or of previous members of that > drive family ? Personally I get wary of Very Large Drives still... (hope the room is real cool) I'm still not too sure of the reliability yet...we'll see...the largest we have are 14 gig drives seems to be holding up so far... but 47 gig humm... does anyone you know been using those for a while (at least as long as they been out)? <...Snip... whew! missed my fingers that time!...> > I guess my main interest, despite the above questions, is really to hear > if others think this is a realistic goal to be aiming for, and if others- > who-have-gone-before-me have struck major problems doing the same (or a > similar) thing. I think its feasable If you aren't too worried about your data if you aren't going the raid route but at least go with hot swappable saves some headache... Spinning down the drives I heard some various problems early on in '97 about that but not too much lately... Terrance Damn what a little research can do.. :-) My few opinions... and fingers... :-) not to be taken with water or used when operating a WinDOZE machine :-) (Hey why'd they give me that NT workstation for...must be to practice rebooting...) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?362F8D9C.ACDA3BF0>