First of all: thank you very much for the advice, Skylar. :) So, all I need to do is to create the same partitions on three disks and set up a RAID 5 on /home since I'll be doing CFD simulations (long sequential writes) and use RAID 1 for other (system) partitions, to account for recovery of the system in case of disk failure because log writes are sequential and small in volume. I was reading about RAID 0, but I'm not sure how safe is to use it for storing computed data and how much speed would I get compared to RAID 5.
Sorry for the totally newbish questions. I'm using Ubuntu, and after I install it, I'll try to configure the RAID manually. How do I make sure that the boot loader is on all disks? I mean, isn't RAID going to make the OS look at the /boot partition that's spread over 3 HDDs as a single mount point? Best regards, Tomislav Skylar Thompson wrote: > Tomislav Maric wrote: >> Hi everyone, >> >> I've finally gathered all the hardware I need for my home beowulf. I'm >> thinking of setting up RAID 5 for the /home partition (that's where my >> simulation data will be and RAID 1 for the system / partitions without >> the /boot. >> >> 1) Does this sound reasonable? >> > It depends on your workload. RAID5 is good for large sequential writes, > but sucks at small sequential writes because for every write it has to > do a read to compare parity. > >> 2) I want to put the /home at the beginning of the disks go get faster >> write/seek speeds, if the partitions are the same, software RAID doesn't >> care where they are? >> > > I don't think this will buy you much performance. There probably is a > measurable difference, but I don't think it's enough to worry about. > >> 3) I'll leave the /boot partition on one of the 3 disks and it will NOT >> be included in the RAID array, is this ok? >> > > Sure, but /boot is actually trivial to mirror. Just make sure your boot > loader is on each disk in the mirror and that each disk is partitioned > identically, and all you have to do if a drive dies is change the device > you boot off of if a drive dies. > >> 4) I've read about setting up parallel swaping via priority given to >> swap partitions in fstab, but also how it would be ok to create RAID 1 >> array of swap partitions for the HA of the cluster. What should I choose? >> > > Any swapping at all will kill performance. I would get enough RAM to > make sure you don't swap. > >> I've gone through all the software raid how-tos, FAQs and similar, but >> they are not quite new (date at least 3 years) and there's no reference >> to clusters. Any pointers regarding this? > > If you're using a Red Hat-based distro, kickstart can handle software > RAID. I don't know about other distros though. > _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
