RE: RAID & Qmail.
Hey Steve, I'm not sure what your question is, you seem to not want to do RAID 5 and can't do RAID 1+0, that leaves RAID 1 if redundancy is required. Were you mistaking RAID 1 and 0? Basically the only question you really need to ask yourself is how much mail you'll end up storing? If you're going to eventually store more mail than the largest pair of hard drives you can afford right now, then RAID 1 won't be an option that will let you easily grow later, you'll need RAID 5 so you can start small now and add disks as needed. I'm sure any decent RAID 5 controller can pump data out fast enough to saturate a fast ethernet segment with NFS reads from your POP3 servers. Dave -Original Message- From: Steve Fulton [mailto:[EMAIL PROTECTED]] Sent: Friday, January 19, 2001 5:00 PM To: [EMAIL PROTECTED] Subject: RAID & Qmail. I've searched the archives extensively, and I've learned quite a lot, but I'd like advice on this question: Assuming RAID 1+0 is not an option (due to the expense), what level of RAID is best for storing /Maildir's on a file server (that will be accessible to the SMTP & POP servers via NFS). Redudancy is the big issue, otherwise I'd go for RAID 1. The suits are pushing for RAID 5 because they don't know better - and won't listen. Steve.
Re: RAID & Qmail.
On Fri, 19 Jan 2001, Steve Fulton wrote: >I've searched the archives extensively, and I've learned quite a lot, but >I'd like advice on this question: > >Assuming RAID 1+0 is not an option (due to the expense), what level of >RAID is best for storing /Maildir's on a file server (that will be >accessible to the SMTP & POP servers via NFS). Redudancy is the big >issue, otherwise I'd go for RAID 1. The suits are pushing for RAID 5 >because they don't know better - and won't listen. > > Steve. Well, not knowing anything about what system you are running, I'll still take a stab at a recommendation. The system that we use here is an x86 system running SuSE Linux 6.4. The only IDE (because I don't need expensive SCSI shit) raid controller I found that would definitely work for what I wanted (redundancy, which is also what you said you wanted) is an Arco Duplidisk. Works in any system that has a PCI slot, even ones that don't natively support PCI (eg. DOS). Sure, the setup of the card is done by booting off a DOS floppy, but after that the card is never seen again by you unless a drive fails. In other words, this is probably the easiest solution for you. -- *** Matthew H Patterson Unix Systems Administrator National Support Center, LLC Naperville, Illinois, USA ***
Re: RAID & Qmail.
Steve Fulton <[EMAIL PROTECTED]> writes on 19 January 2001 at 16:59:33 -0500 > I've searched the archives extensively, and I've learned quite a lot, but > I'd like advice on this question: > > Assuming RAID 1+0 is not an option (due to the expense), what level of > RAID is best for storing /Maildir's on a file server (that will be > accessible to the SMTP & POP servers via NFS). Redudancy is the big > issue, otherwise I'd go for RAID 1. The suits are pushing for RAID 5 > because they don't know better - and won't listen. Um; 0 is striping, 1 is mirroring, right? I don't do this enough to be confident of the numbers. So if mirroring is too expensive, the only option available for consideration is RAID 5, parity. It has less redundancy than mirroring, but good reliability (survives loss of one disk). -- David Dyer-Bennet / Welcome to the future! / [EMAIL PROTECTED] SF: http://www.dd-b.net/dd-b/ Minicon: http://www.mnstf.org/minicon/ Photos: http://dd-b.lighthunters.net/
Re: RAID & Qmail.
raid 4 is also an option - NetApp. however, they tend to be pricey. David Dyer-Bennet writes: > Steve Fulton <[EMAIL PROTECTED]> writes on 19 January 2001 at 16:59:33 -0500 > > I've searched the archives extensively, and I've learned quite a lot, but > > I'd like advice on this question: > > > > Assuming RAID 1+0 is not an option (due to the expense), what level of > > RAID is best for storing /Maildir's on a file server (that will be > > accessible to the SMTP & POP servers via NFS). Redudancy is the big > > issue, otherwise I'd go for RAID 1. The suits are pushing for RAID 5 > > because they don't know better - and won't listen. > > Um; 0 is striping, 1 is mirroring, right? I don't do this enough to > be confident of the numbers. So if mirroring is too expensive, the > only option available for consideration is RAID 5, parity. It has > less redundancy than mirroring, but good reliability (survives loss of > one disk). > -- > David Dyer-Bennet / Welcome to the future! / [EMAIL PROTECTED] > SF: http://www.dd-b.net/dd-b/ Minicon: http://www.mnstf.org/minicon/ > Photos: http://dd-b.lighthunters.net/ - Paul Theodoropoulos [EMAIL PROTECTED] Senior Unix Systems Administrator Syntactically Subversive Services, Inc. http://www.anastrophe.net Downtime Is Not An Option
Re: RAID & Qmail.
David Dyer-Bennet wrote: > > Steve Fulton <[EMAIL PROTECTED]> writes on 19 January 2001 at 16:59:33 -0500 > > I've searched the archives extensively, and I've learned quite a lot, but > > I'd like advice on this question: > > > > Assuming RAID 1+0 is not an option (due to the expense), what level of > > RAID is best for storing /Maildir's on a file server (that will be > > accessible to the SMTP & POP servers via NFS). Redudancy is the big > > issue, otherwise I'd go for RAID 1. The suits are pushing for RAID 5 > > because they don't know better - and won't listen. > > Um; 0 is striping, 1 is mirroring, right? I don't do this enough to > be confident of the numbers. So if mirroring is too expensive, the > only option available for consideration is RAID 5, parity. It has > less redundancy than mirroring, but good reliability (survives loss of > one disk). You are correct. Zero (0) is striping, one (1) is mirroring and five (5) is parity. The OPs wording is confusing, or he's got 0 and 1 reversed in his head somehow (or a complete misunderstanding of RAID levels) For the curious (just the first hit I found from Google ;) ): http://www.express-inc.com/docs/diskarry/raid.htm GW
Re: RAID & Qmail.
Steve Fulton wrote: > > I've searched the archives extensively, and I've learned quite a lot, but > I'd like advice on this question: > > Assuming RAID 1+0 is not an option (due to the expense), what level of > RAID is best for storing /Maildir's on a file server (that will be > accessible to the SMTP & POP servers via NFS). Redudancy is the big > issue, otherwise I'd go for RAID 1. The suits are pushing for RAID 5 > because they don't know better - and won't listen. > > Steve. Hi, I wish point you a reference regarding SMTP & POP via NFS: - I think NFS is a little slow and it locks the file-system which is not a good idea in case the NFS server will go down for a while. I have RAID 1 between two fail-over qmail servers using NBD (network block device) and a local partition for each one. In case one of my qmail-server is down the other will take care about qmail service without any file-system unlock, just start its NBD service and reconstructing the RAID 1 locally. If you want more details about NBD go to: - http://www.it.uc3m.es/~ptb/nbd/ <-- home-page - http://lists.community.tummy.com/mailman/listinfo/enbd <-- mail-list I think you can use RAID 5 and NBD too in case you lack in local disk controllers. Regards, -- Adrian Turcu System Administrator Computers Department Romanian Railway Company Constanta Region E-mail: [EMAIL PROTECTED], [EMAIL PROTECTED] Phone: +40 92 563791 (any time) +40 43 363977 (home)
Re: RAID & Qmail.
> > Have you had any problems?... > There were some problems, especially with RAID and ENBD software. First, I try to figure out how ENBD works, in fact when the NBD server is going down what are the possibilities for the NBD client to know that and "make an announcement" to RAID software and the last to unbind the partition from its configuration. Of course, after a carefully read of ENBD docs, I was able to deal with this problem. One other problem (for me) was with linux kernel RAID support, because you have to make a compromise between a small modularized kernel and a "huge" speedy and reliable one. I choose the last. > >... What sort of throughput > do you get? Have you had to actually do a rebuild? How much data are you storing? > The throughput depends of the NIC's you are using and it is not dramatically limited to much by the software (RAID and ENBD). There are some compares between NFS and ENBD in the ENBD docs and you could see how fast is ENBD (it is fast, if you can trust me). What I can say is: - for reconstruction I am using 2 * 10BaseT NIC on each computer (3Com) - both computers are running 2.2.16 kernel optimized - one of those computers (the master) is PII-450MHz/64M RAM/IDE and the other (the slave) is Pentium 100MHz/48M RAM/SCSI - the partition for qmail is 1GByte large (small site) In the consideration above, a full reconstruction it takes ~20min or less, depending the load of the master which also running NS. I think a rate of 5Mbit/sec it could be OK. It can be raised in multi-processor configuration, more RAM on each nodes, SCSI on both, 100BaseT or 1GByte ethernet and same architecture. > Thanks, > Rick. It was my pleasure. Regards, -- Adrian Turcu System Administrator Computers Department Romanian Railway Company Constanta Region E-mail: [EMAIL PROTECTED], [EMAIL PROTECTED] Phone: +40 92 563791 (any time) +40 43 363977 (home)
Re: RAID & Qmail.
On Fri, Jan 19, 2001 at 04:59:33PM -0500, Steve Fulton wrote: > I've searched the archives extensively, and I've learned quite a lot, but > I'd like advice on this question: > > Assuming RAID 1+0 is not an option (due to the expense), what level of > RAID is best for storing /Maildir's on a file server (that will be > accessible to the SMTP & POP servers via NFS). Redudancy is the big > issue, otherwise I'd go for RAID 1. The suits are pushing for RAID 5 > because they don't know better - and won't listen. Why is RAID 5 and option if RAID 1+0 isn't? The latter only requires 4 drives in the minimum configuration. You can even do it with IDE drives using 3ware's IDE RAID controllers. John
