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OTOH, I was in the storage industry until recently, and HD capacity increases were always welcome. That is because we were a bandwidth play, sold on the basis o

OTOH, I was in the storage industry until recently, and HD capacity increases were always welcome. That is because we were a bandwidth play, sold on the basis of density and capacity. Hello backup and archive. That is frankly where most of HD storage is today, 40 drives sitting in 4U is still a few ten-thousand ops per second, but it has a few tends of GB/sec of bandwidth too. So, if your access patterns are long linear read/writes then HDD's work just fine. Even for midrange IOP applications, if you burst a couple GB from disk to a SSD cache, its possible to absorb a lot of IOP's. Also, rebuild/scrub operations aren't really an issue either if your running RAID6, and your system is sufficiently designed/over provisioned to deal with rebuild/scrub operations happening in the background. If your IOP limited OTOH, you likely have a problem.

notacoward 8y ago
> Hello backup and archive. That is frankly where most of HD storage is today I'm not sure whether that's true or not. At one end, tape still exists. At the other end, a lot of data that's already stored with high levels of redundancy doesn't get backed up anywhere else. Do you have a good source for a definitive answer? > rebuild/scrub operations aren't really an issue either if your running RAID6 Rebuild/scrub operations still happen, and are still an issue, with RAID6. They might not be quite as visible because they're not soaking up host cycles, but they are soaking up disk IOPS. In any large or even medium-sized storage infrastructure (by today's standards) you'll have some going on and occasionally you'll have some that overlap because the first one took too long. Before long you'll hit a case where you get a third failure while the first two are still going on, and you stop relying on insufficient RAID6. Then you're into erasure codes and your own kind of scrubbing. Those aren't exotic situations or responses any more. > If your IOP limited OTOH, you likely have a problem. Yep, sure do. Can't wish it away, or make it all better with a magical free SSD caching layer. Have to solve it, which requires effort and expense. What I'm saying is that bigger disks make that harder. I'm not complaining, it's what I and others choose to do, but it's a fact.
- StillBored 8y ago
  I don't have a direct summary link, but if you read random storage revenue/capacity reports that seems to be the case. There are a few large buyers of bulk storage which appear to be using it for some form of nearline. At least in my experience (which is obviously warped by the part of the industry I was in), enterprise applications needing IOP's have been overwhelmingly moving to pure flash. There remains a large amount of revenue in hybrid arrays, but the volume is shrinking (although maybe not the raw capacity, similar to the mainframe which is selling record amounts of capacity in fewer and fewer machines). A few years ago I stopped being surprised to see a couple racks of infortrend's or supermicro storage chassis (or any number of other 2nd tier vendors products) sitting at one end of random datacenters, where the local storage admins were running some huge snapshot repo, or Ceph, or whatever on them and the resulting capacities were frequently powers of ten greater than the online storage. Also, I've seen plenty of tape arrays too, but they don't seem nearly as common these days. Partially, because tape has the same problems as disk (lots of bandwidth, but it never seems to be enough). It seems everyone still has one, but you have to hunt for it, and it might only be getting the most critical data (or stuff that is required for compliance with some law), which turns out to be limited by the 2-4-8 drives they have constantly spinning, where an operator walks in every few days and swaps a couple dozen tapes offsite. Sure there are larger libraries but it seems most admin's start any conversation about tape with a groan and eye rolling, which tends to be an attitude that keeps finite resources from being heavily invested in them. So, people will buy 10+Gbit links between their data centers (which sometimes tend to be shockingly inexpensive) rather than spend $10k on a tape library and a fedex account.

notacoward 8y ago

> Hello backup and archive. That is frankly where most of HD storage is today I'm not sure whether that's true or not. At one end, tape still exists. At the other end, a lot of data that's already stored with high levels of redundancy doesn't get backed up anywhere else. Do you have a good source for a definitive answer? > rebuild/scrub operations aren't really an issue either if your running RAID6 Rebuild/scrub operations still happen, and are still an issue, with RAID6. They might not be quite as visible because they're not soaking up host cycles, but they are soaking up disk IOPS. In any large or even medium-sized storage infrastructure (by today's standards) you'll have some going on and occasionally you'll have some that overlap because the first one took too long. Before long you'll hit a case where you get a third failure while the first two are still going on, and you stop relying on insufficient RAID6. Then you're into erasure codes and your own kind of scrubbing. Those aren't exotic situations or responses any more. > If your IOP limited OTOH, you likely have a problem. Yep, sure do. Can't wish it away, or make it all better with a magical free SSD caching layer. Have to solve it, which requires effort and expense. What I'm saying is that bigger disks make that harder. I'm not complaining, it's what I and others choose to do, but it's a fact.

StillBored 8y ago
I don't have a direct summary link, but if you read random storage revenue/capacity reports that seems to be the case. There are a few large buyers of bulk storage which appear to be using it for some form of nearline. At least in my experience (which is obviously warped by the part of the industry I was in), enterprise applications needing IOP's have been overwhelmingly moving to pure flash. There remains a large amount of revenue in hybrid arrays, but the volume is shrinking (although maybe not the raw capacity, similar to the mainframe which is selling record amounts of capacity in fewer and fewer machines). A few years ago I stopped being surprised to see a couple racks of infortrend's or supermicro storage chassis (or any number of other 2nd tier vendors products) sitting at one end of random datacenters, where the local storage admins were running some huge snapshot repo, or Ceph, or whatever on them and the resulting capacities were frequently powers of ten greater than the online storage. Also, I've seen plenty of tape arrays too, but they don't seem nearly as common these days. Partially, because tape has the same problems as disk (lots of bandwidth, but it never seems to be enough). It seems everyone still has one, but you have to hunt for it, and it might only be getting the most critical data (or stuff that is required for compliance with some law), which turns out to be limited by the 2-4-8 drives they have constantly spinning, where an operator walks in every few days and swaps a couple dozen tapes offsite. Sure there are larger libraries but it seems most admin's start any conversation about tape with a groan and eye rolling, which tends to be an attitude that keeps finite resources from being heavily invested in them. So, people will buy 10+Gbit links between their data centers (which sometimes tend to be shockingly inexpensive) rather than spend $10k on a tape library and a fedex account.