Error corrected
Great magazine, thank you. I’ve just re-read your article on the ultimate home server in LXF213, and realised you go into a lot of detail on RAID to protect data, but on the previous page, in the small hardware box, you say any dual-core Pentium will do.
I think this is a tad lacking in consistency, as the standard Pentiums etal do not support ECC, and if you look at the reliability of DRAM, as shown in some tests ( www.cs.toronto.
edu/~bianca/papers/
sigmetrics09.pdf), you don’t want to store data, in such a safe place as RAID, the already flipped bits your low-tech CPU has passed to the storage system from RAM.
Please recommend a system that provides ECC, because if you do not go Intel, you can have ECC for not a lot more than not using ECC, and thus protect all parts of the system. I know Intel leaves memory as the only unprotected element of a system to try to get people to pay for Xeon, but home users do not need Xeon, just ECC.
ChrisLee,viaemail
Jonni says: I definitely should have mentioned ECC RAM and its
raisond’être in the Ultimate Home Server feature. However, I’m not sure I agree with you about ECC memory being absolutely necessary here. Definitely memory errors occur, and having ECC RAM will protect you against most of them, but I don’t think that peace of mind is really worth the platform upgrade. There are all kinds of other things that could go wrong, with the same or higher probabilities as a memory bitflip – disk errors, power failures, Steam crashing, and users messing up their files.
One case where you are quite correct to insist on ECC is if you have a large ZFS array. ZFS stores much more data in memory than other filesystems, so it’s much more likely that a random in-memory bitflip is going to affect file data or metadata.
I know, the right bitflip might, for any filesystem, cause data to get written to the wrong sector of the drive and cause untold damage, but you’d have to be really unlucky for that to happen. If you have extra money to spend to allow ECC support, then one could argue that the money would be better spent on a UPS or more reputable memory/other components. If you really care about your data, you want redundancy (probably a four or six-drive RAID 6, maybe four-drive RAID 10), daily backups (on and off-site), a checksumming filesystem like ZFS or Btrfs, and limited access to both the files and the hardware. All of this is probably overkill for a simple home server appliance. We even had someone write in and say the RAID 1 scheme I recommended was unnecessary and overcomplicating the setup. I disagreed with them, too.