On Mon, Jul 07, 2014 at 06:08:15PM +0200, Ibrahim Tachijian via smartos-discuss wrote:
> Hey Joyent and every other smartos user. > > We are trying to narrow down a few of our hardware choices to meet our > requirement. > > Our requirements is well defined and we know exactly what we expect from > the proposed array. > We have barely any CPU power necessary so a single quad core is enough for > us. > > Requirements: > > > - Write operations:* (24/7)* > - *Approx 200 consecutive writes each write at 5mbit/s * > - > *[Total: 125MB/s writes] * > - Read operations (*150 consecutive reads* is the UPPER limit, might > be less). > - Approx 150 consecutive reads each read at* 5mbit/s* > - [Total: *93MB/s reads*]. > - Storage capacity 15TB of actual space (Not counting space lost to > RAIDZ levels or mirrored vdevs) > > Our proposal is: > > > - E5-1620v2 (Quad 3.7ghz Xeon) > - 128gb of DDR3 ECC REG RAM > - SAS Disks from HGST (Count and Size of each drive to be determined) > - Proposed drive HGST SAS HUS724040ALS640 > > > - ZFS "sync" setting set to disabled. Data loss is not an issue for us, > we only care about performance. > - Dedupe off, compression off (We're saving video) > - ZIL is unnecessary because of "sync" disabled. I assume you mean 'slog'. There's always a ZIL. > - RAIDZ level? We are unsure. > > Given these parameters, and the experience joyent has had with HGST 4TB SAS > drives. How large of an array, and what RAIDZ or mirrored vdev > (raid10-like) would I require to be able to meet my above mentioned > requirements? Your basic choices here are: 6 x 4 TB disks, RAIDZ-2, single vdev. This will provide you with about the same number of IOPS at a given latency as a single disk would (probably somewhere between 60 and 100). 8 x 4 TB disks, mirror, 4 vdevs. This will provide you with about 4x as many IOPS at a given latency. Add a hot spare to either one if desired (I'd recommend it). Given the modest difference in cost between the two options, I'd spring for the mirror. If every dollar/euro counts or you have plenty of time for testing, buy 6 and try RZ2 to start, measure performance, and if it's not acceptable buy 2 more and rebuild the pool. The big question is whether your reads and writes will be interleaved in such a way that the disks can't stay in streaming mode; if so, you'll be very thankful for the mirror. ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
