Using flash on the server side
Upcoming SlideShare
Loading in...5
×
 

Using flash on the server side

on

  • 545 views

 

Statistics

Views

Total Views
545
Views on SlideShare
539
Embed Views
6

Actions

Likes
0
Downloads
8
Comments
0

1 Embed 6

https://twitter.com 6

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Using flash on the server side Using flash on the server side Presentation Transcript

  • Using Flash on The Server Side Or How this Flash Makes Storage Like This Flash
  • Flash/SSD Form Factors • 2.5” SSD – SATA for laptops, good for servers – SAS Dual ports for dual controller arrays • PCIe – Lower latency, higher bandwidth • SATA Express – 2.5” PCIe frequently with NVMe • Memory Channel Flash (SanDisk UltraDIMM) – Write latency as low as 3µsec – Requires BIOS support
  • Anatomy of an SSD • Flash Controller – Provides external interface • SATA • SAS • PCIe – Wear leveling – Error correction • DRAM – Write buffer – Metadata • Ultra or other capacitor – Power failure DRAM dump – Enterprise SSDs only
  • Flash in the Server • Minimizes latency & maximizes bandwidth – No SAN latency/congestion – Dedicated controller • PCIe flash example – 1.6GB/s bandwidth – >50µs read, >20µs write latency • But servers are unreliable – Data on server SSD is captive
  • Server Side Deployment Models • As direct storage – Very high performance but limited resiliency – Resiliency responsibility of applications • HPC like checkpointing • Web 2.0 app data distribution • SQL Server Always On • As pooled/replicated storage – Virident software – Replicates, pools via RDMA
  • Server Flash Caching Advantages • Take advantage of lower latency – Especially w/PCIe flash card/SSD • Data written to back end array – So not captive in failure scenario • Works with any array – Or DAS for that matter • Allows focused use of flash – Put your dollars just where needed – Match SSD performance to application • Politics: Server team not storage team solution
  • Server Side Caching Suppliers • Independent Software Vendors – Proximal Data – PernixData • Array vendors – EMC – NetApp • Server vendors – HP – Dell • Qlogic • SSD vendors – Intel • Nevex – Samsung • Nvelo – SanDisk • Flashsoft – Western Digital • sTec EnhanceIO • Velobit Hypercache – OCZ – Virident
  • Use Cases • Database servers – Good fit with shared nothing clusters – Look for OS, SSD support • Server virtualization – Higher random I/O rates – Look for: • Dynamic cache assignment • Live migration support • VDI – Write intensive but captive data less of an issue
  • Caching Boosts Performance! 0 500 1000 1500 2000 2500 3000 3500 Baseline PCIe SSD Cache Low end SSD Cache Published TPC-C results
  • Write Through and Write Back 0 10000 20000 30000 40000 50000 60000 Baseline Write Through Write Back TPC-C IOPS • 100 GB cache • Dataset 330GB grows to 450GB over 3 hour test
  • Architectures • Caching software in OS – File or block filter driver • Caching software in Hypervisor – File or block filter • Vendor may need custom hooks • Virtual Storage Appliance • Hardware cache device – RAID Controller for DAS – HBA/CNA
  • Software Caching Locations
  • Basic Cache Types • Read • Write Through – Cache populated on write – Data written to back end before ack • Write Back – Data acknowledged on write to cache – Written to back end storage asynchronously
  • Write Back? • Write back caches speed up writes too • Data must be protected – Flash is non-volatile – Servers are unreliable – Server crash leads to imprisoned data • Move SSD to new server w/cache software • Flush cache before resume • Array snapshot issues
  • Distributed Cache • Duplicate cached writes across n servers • Eliminates imprisoned data • Allows cache for servers w/o SSD • Products: – PernixData – Virident – Others soon • Qlogic FabicCache caching HBA acts as target & initiator
  • Live Migration Issues • Does cache allow migration – Through standard workflow • To allow automation like DRS? • Is cache cold after migration? • Cache coherency issues • Guest cache – Cache LUN locksVM to server • Can automate but breaks workflow • Hypervisor cache – Must prepare, warm cache at destination
  • Copy Cache During Migration • Migration includes cache contents • More data • Extends migration time • Requires new workflow or hypervisor support • Now available from ProximalData
  • Questions and Contact • Contact info: – Hmarks@deepstorage.net – @DeepStoragenet onTwitter