4 ms·
Hot and cold spares are rather wasteful. Just RAID1 and then use software (i.e. ceph) to make that redundant across multiple enclosures and ultimately, geograph
by Narkov 8y ago
Hot and cold spares are rather wasteful. Just RAID1 and then use software (i.e. ceph) to make that redundant across multiple enclosures and ultimately, geographic zones/DC's.
- hobs 8y agoDepends on your RPO and RTO tbqh, if you have the budget to do that in software you are either fairly small or able to implement changes without the business yanking your chain and many are willing to just pay more for their storage layer than re-architect existing apps.
- mmt 8y agoThat strikes me as a bit contradictory, since I would consider RAID1 (plus the redundancy across enclosures) to be the equivalent to even "hotter"[1] spares. Unlike the hot (warm) and cold spares for the RAID5/6, all the drives in the RAID1 are continuously in use, which means they're subject to wear-related failures [2]. If you're getting performance benefits from the RAID1, then the extra drives may not be wasted, but that's a separate topic. [1] Which I argue is a misnomer. To me, "warm spare" makes more sense, since it's powered up but not actively synced in any way. Some systems, configurably, even spin down such spares. [2] As I mentioned in https://news.ycombinator.com/item?id=17855632 https://news.ycombinator.com/item?id=17855632 some failures are power-on/spun-up related, which makes the availability of a truly cold spare even more beneficial.