On Wed, Aug 03, 2016 at 01:07:24AM +1000, Russell Coker wrote: > It's nice that you can get a case that can handle 8 disks for $200.
cases that handle 8+ disks are common enough, but 8 hot-swap bays (and 4 more internal drive bays) in a small case is amazing. very nice. i wish they'd been around years ago. they're ideal for DIY NAS, with plenty of room to grow. > But as 6TB disks are affordable and 8TB disks are available hardly > anyone needs more than 4 disks for a home server. I don't know if i trust the 6 or 8TB drives yet. maybe in a year or so. oh, and don't use SMR drives like the Seagate "Archive" drives for anything but read-mostly uses - occasional writes are OK, but frequent writes (even typical desktop usage patterns) will be horribly slow. and don't use them in raid or raid-like (btrfs,zfs) setups. and size isn't everything. multiple smaller disks in RAID-1/10 will give much better performance. 4x2TB RAID-10 will cost 10-20% more than 2x4TB RAID-1 but will be much faster. > If you want a server for serious performance then a couple of large > SATA disks for main storage and a couple of NVMe devices in PCIe cards > for ZIL and L2ARC would be the way to go. btw, i don't have the link handy but i recently saw an announcement for a PCI-e card that i've been hoping for ages that someone would make - a PCI-e x16 card with four x4 NVMe slots on it. a DIY NAS with built-in GPU and a single PCI-E slot could make good use of that. > In the long term I think that 2.5" disks won't be a useful option > for many people. Anyone who is designing a laptop now should design > for M.2 except for the corner-case of >15" laptops. Anyone who is > designing a motherboard now should include 2*M.2 sockets on it. i've got nothing against NVMe (in fact, it's one of the technologies I'm keenly waiting to get better and cheaper), but they have different use cases than 2.5" or 3.5" drives. 2.5" drives will be useful for years to come. NVMe (esp. in raid-1) is great for an OS drive and for bcache/l2arc/zil/etc but capacity is limited due to the small size and, worse, pci-e lanes are limited (esp. in Intel motherboards) so very few motherboards will have more than 1 or 2 M.2 slots. i haven't yet seen any NVMe hot-swap capability either, which means taking the system down to replace a drive. SATA3 SSDs get up to around 550MB/s. 4 of them in RAID-1 or RAID-10 will get nearly 2GB/second read speed, and over 1TB/s write. and the more mirrored pairs you add, the faster it gets. That's fast enough that it doesn't need an NVMe for caching. > For all storage nowadays you either want the speed of SATAe (which > is most easily realised with M.2) or the capacity and price of 3.5" > disks. part of my point was that SSDs are getting cheaper all the time. In the not too distant future, they will be cheap enough for home users to build reasonably large arrays of 1-4TB SSDs, with much greater performance, especially on random seeks or programs that open files with O_SYNC or just fsync a lot. It's easy and cheap to get hot swap bays that let you put four 2.5" drives in a single 5.25" bay (or 12 in 3x5.25" bays if you don't like the noise of little 40mm fans). also adapters to fit 2x2.5" in a 3.5" bayṫ > Finally instead of buying systems for such use getting them for free > is a better option for most people. yep, that's why i suggested scrounging. craig -- craig sanders <[email protected]> _______________________________________________ luv-main mailing list [email protected] https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main
