BEFORE THIS TURNS INTO A PISSING CONTEST ... BE NICE, BE NICE, BE NICE -- Johnny Hughes CentOS 4 Developer ... and mailman admin for this list :) On Wed, 2005-10-26 at 01:58 -0700, Benjamin Smith wrote: > Bryan, > > If my viewpoint is limited, I have within my email defined (to the best of my > ability) the limits of my viewpoint. Use as you see fit. > > Take a big, fat, chill pill, and realize that you're amongst friends, eh? > Where have I applied absolutes? Is it not true that hardware RAID > "frequently" leaves you locked in? Not "ALWAYS" (which would be an > "absolute") but frequently? "several vendors don't lock you in" doesn't sound > much like "infrequent" to me. > > And, if performance isn't a big issue, why bother with HW RAID? There are many > circumstances where data integrity is important, but a few hours of downtime > won't kill anybody. > > I'm glad you like your 3ware card(s). But I've made stuff work and work well > on 1/10 your price (where $100 includes the entire computer sans monitor) > with software RAID. > > Spend your $100 however you like. I offer my opinion, and I offer clear > qualifications on the scope of my opinions. If you're running Yahoo, $100 is > not even on the radar. But, if you're running a server for a 6-man company, > $100 can be the difference between gaining and losing a contract. > > So, get off your high horse, offer your endorsements of the 3ware cards to the > rest of us, and relax already! > > -Ben > > PS: If my butt is on the line and it's located 1,000 miles away, I'm going to > demand 24x7 "hot hands" at a high quality colo with qualified staff. (and I > do currently) There are many things that can go wrong, only one of which is a > HDD failure, and if a controller card is all you feel you can count on, may > god have mercy on you and your clientelle! > > On Tuesday 25 October 2005 17:38, Bryan J. Smith wrote: > > [ I really dislike these discussions because it is often > > opinions that are based on limited viewpoints. I've used a > > lot of software and hardware approaches over many different > > platforms and many different systems, and what I repeatedly > > see is absolutes applied when they are not applicable to many > > vendors. ] > > > > Benjamin Smith <lists at benjamindsmith.com> wrote: > > > I've not yet tried Software RAID 1 with Centos 4.x but I've > > > done so with Fedora Core 1 / X86-32 so I'd assume that my > > > comments would apply. > > > > Just be wary of changes in MD and/or LVM/LVM2. > > > > > I tend to prefer software RAID simply because then I'm not > > > locked to a specific vendor/controller. > > > > With RAID-1 (and not even block-striped RAID-0 or 10), > > several vendors don't "lock you in." Not only can you > > typically read the disk label on the "raw" disk, but there is > > support for reading volumes of different drives. > > > > In fact, this is how LVM2+DM (DeviceMapper) is adding support > > for FRAID in kernel 2.6. > > > > > If a hardware failure occurs that takes out the controller > > > but leaves at least one of the HDDs ok, I can take one > > > software RAID HDD, stick it into another controller, and > > > have a working system in very short order. > > > > So can I, and I have done so when I didn't have a 3Ware > > Escalade or equivalent FRAID card around. > > > > > Hardware RAID frequently does not have this advantage. > > > > That is an absolutely _false_ technical statement with > > regards to _several_ vendors. Please stop "blanket covering" > > all "Hardware RAID" with such absolutes. > > > > > When I've set up RAID, I did so with the RH installer, and > > > have always picked RAID1. > > > > I'm a huge fan of RAID-1 and RAID-10. > > > > > (RAID5 is a joke for SW RAID) > > > > Agreed. The newer Opteron systems help as long as they have > > an excellent I/O design, but that loads much of the > > interconnect doing just I/O operations for the writes (let > > alone during rebuilds) -- loads that could be doing data > > services. > > > > > I've set up a number of RAID installs with "boot/root" and > > > extensions using the Software RAID howto. (google it) > > > > And I have as well. Unfortunately, the main concern is > > headless/remote recovery when the disk fails. Installing the > > MBR and bootstrap so it can boot from another device when the > > BIOS still sees the original, yet failed, disk is the issue. > > > > Until the LVM2+DM work supports more FRAID chips/cards to > > overcome the BIOS mapping issue (not likely until the FRAID > > vendors recognize and support the DM work), I still prefer at > > $100 3Ware Escalade. > > > > > Experimentally, I've set up a RAID array, removed one > > > drive, booted, shutdown, and then replaced it with the > > > other. > > > > As have I, on non-x86/non-Linux architectures as well as > > Linux. But if you have a headless/remote system, and the > > first drive fails, that doesn't solve the issue the BIOS > > mapping. > > > > > Both drives booted fine, so there doesn't appear to be > > > any particular issue with grub. > > > > As long as you have physical access to the system. > > > > > When done, I had to resync the drives (again, see the > > > Software RAID howto) > > > > I prefer autonomous operation. It's worth $100 IMHO. > > > > > The only time I ran into trouble is that when you set up a > > > RAID array, you have to have all the partitions installed > > > on the machine at setup time. > > > > _Not_ true with even software RAID! > > > > If you aren't using LVM, then yes, you have to pre-partition. > > But even then, you can define new MD slices. > > > > But if you are using LVM/LVM2 (whether LVM/LVM2 is atop of a > > MD setup, or you create MD slices in LVM/LVM2 extents), you > > can dynamically create slices, fileystems, etc... without > > bringing down the box. > > > > > It seems you can't add active partitions after the fact. > > > > I think you're mixing the fact that it is difficult to > > "resize" MD slices with adding "active" partitions. Those > > are more limitations with the legacy BIOS/DOS disk label than > > Linux MD, which LVM/LVM2 solves nicely. > > > > [ Just like LDM Disk Labels solve for Windows NT5+ (2000+) ] > > > > > Other than that, in 5 cases, it's been basically perfect > > > for me, and I plan to deploy Centos 4.x/Software > > > RAID/Boot-root again sometime next month. > > > > As have I. But at the same time, I find that putting in a > > $100 3Ware card has saved my butt. > > > > Like the time the first disk failed 1,000 miles away, and the > > BIOS was still mapping the primary disk which it couldn't > > boot from. > > > > Since then, I have refused to put in a co-located box without > > a 3Ware Escalade 700x-2 or 800x-2 card. The system has to be > > able to boot without local modification. > > > > > > -- > > Bryan J. Smith | Sent from Yahoo Mail > > mailto:b.j.smith at ieee.org | (please excuse any > > http://thebs413.blogspot.com/ | missing headers) > > _______________________________________________ > > CentOS mailing list > > CentOS at centos.org > > http://lists.centos.org/mailman/listinfo/centos > > > -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part URL: <http://lists.centos.org/pipermail/centos/attachments/20051026/69eccdff/attachment-0005.sig>