3 ms·

Might be somewhat niche, but this is looks to be a near perfect match for SLOG usage in ZFS based storage schemes where a certain amount of synchronous writes a

by xoa 10y ago

Might be somewhat niche, but this is looks to be a near perfect match for SLOG usage in ZFS based storage schemes where a certain amount of synchronous writes are important. SLOGs don't need much raw space or massive throughput, they need low latency and reliability (including of course persistence in the case of power loss). Traditionally this has been handled either (suboptimally) by flash drives (preferably SLC) or by battery backed RAM drives, which are extremely expensive and have their own potential failure modes. This though looks almost exactly right and could become the new basic answer. In fact it's cheap enough and good enough that it may make ZFS users who previously decided it wasn't cost effective enough to bother with even if some gains were available reconsider.

olavgg 10y ago
This is great for anything that needs high iops when doing sync writes. Ceph journal, fsync system calls, database systems and so on.
loeg 10y ago
Something to consider for SLOG (or other journals, e.g., bcache) is that write endurance of the Optane 16-32 GB models is pretty poor. You might want a bigger Optane (or SSD) as a writeahead log / WB cache not because you need the capacity, but because you need the write endurance.
- xoa 10y ago
  Absolutely an important consideration, and it certainly depends on the use case. The IOPS also isn't remotely as high as the larger models or a ram drive (though SLOGs can be striped for more). But it's $44/$77 whereas the P4800X starts at ~$1500 and something like the DDRdrive X1 (4GB RAM/4GB SLC NAND/power backing) is ~$2k. For a lot of individual applications (and remember, sync behavior can be set per dataset and SLOGs are assigned per pool) even the limited write endurance will be sufficient for a significant period of time, and even if these initial Optanes were burned through within a single year it could still be dramatically more cost effective: at these prices we're talking decade(s) of yearly replacements before equalling the cost of one higher end drive. Also consider where we are on the development curve for this tech. This is effectively 1.0 of XPoint technology, so it's reasonable to expect significant improvements in capacity/$, performance, and so on over the next few years, which in turn means it may be desirable to cycle them relatively fast anyway. What I had in mind wasn't that these would be replacements for existing solutions used for high sustained intensity applications directly making money. Those are covered by ram drives or striped SLC already (and perhaps the P4800X series soon). I was more thinking the Optane Memory might provide a solid route for experimentation by a new class of users given the capex of a few pizzas. A lot those cases are going to be relatively low sustained intensity, but with burst performance still desirable. Heck, for forty someodd bucks some might go for it just to do some profiling and get a feel for what a separate ZIL would do for them at all. If anything a significant limiting factor right now may simply be the relative availability/preciousness of M.2 slots in deployed home/soho appliances, servers and workstations.
  - loeg 10y ago
    Yep, those are all good points. Thanks for sharing your thoughts :-).

by xoa 10y ago

olavgg 10y ago

This is great for anything that needs high iops when doing sync writes. Ceph journal, fsync system calls, database systems and so on.

loeg 10y ago

Something to consider for SLOG (or other journals, e.g., bcache) is that write endurance of the Optane 16-32 GB models is pretty poor. You might want a bigger Optane (or SSD) as a writeahead log / WB cache not because you need the capacity, but because you need the write endurance.

xoa 10y ago
Absolutely an important consideration, and it certainly depends on the use case. The IOPS also isn't remotely as high as the larger models or a ram drive (though SLOGs can be striped for more). But it's $44/$77 whereas the P4800X starts at ~$1500 and something like the DDRdrive X1 (4GB RAM/4GB SLC NAND/power backing) is ~$2k. For a lot of individual applications (and remember, sync behavior can be set per dataset and SLOGs are assigned per pool) even the limited write endurance will be sufficient for a significant period of time, and even if these initial Optanes were burned through within a single year it could still be dramatically more cost effective: at these prices we're talking decade(s) of yearly replacements before equalling the cost of one higher end drive. Also consider where we are on the development curve for this tech. This is effectively 1.0 of XPoint technology, so it's reasonable to expect significant improvements in capacity/$, performance, and so on over the next few years, which in turn means it may be desirable to cycle them relatively fast anyway. What I had in mind wasn't that these would be replacements for existing solutions used for high sustained intensity applications directly making money. Those are covered by ram drives or striped SLC already (and perhaps the P4800X series soon). I was more thinking the Optane Memory might provide a solid route for experimentation by a new class of users given the capex of a few pizzas. A lot those cases are going to be relatively low sustained intensity, but with burst performance still desirable. Heck, for forty someodd bucks some might go for it just to do some profiling and get a feel for what a separate ZIL would do for them at all. If anything a significant limiting factor right now may simply be the relative availability/preciousness of M.2 slots in deployed home/soho appliances, servers and workstations.
- loeg 10y ago
  Yep, those are all good points. Thanks for sharing your thoughts :-).