Disk IO Benchmarking in the Cloud

This is the second post in our series on cloud server performance benchmarking. The previous blog post, What is an ECU? CPU Benchmarking in the Cloud, focused strictly on CPU performance. In this post, we'll look at disk IO performance. Choosing a cloud provider should be based on a many factors including performance, price, support, reliability/uptime, scalability, network performance and features. Our intent is to provide a good reference for those looking to use cloud services by providing objective analysis in regards to all of these factors.

Benchmark Setup

All benchmarked cloud servers were configured almost identically in terms of OS and software, CentOS 5.4 64-bit (or 32-bit in the case of EC2 m1.small and c1.medium and IBM's Development Cloud where 64-bit is not supported). File systems were formatted ext3.

Benchmark Methodology

In the previous post we used Amazon's EC2 ECU (Elastic Compute Unit) as a baseline for comparison of CPU performance between providers. In terms of disk performance, there really isn't a common term synonymous to the ECU. However, most readers will be at least be somewhat familiar with hardware disk IO performance factors such drive types (SAS, SATA), spindle speeds (10K, 15K) and RAID levels. So, we chose to use a "bare-metal" cloud server as the baseline for disk IO performance in this post. Our experience has been that most providers will not disclose much technical detail about their underlying storage systems. However, in the case of Storm on Demand's new Bare Metal Cloud Servers they fully disclose most technical details about their servers (one of the selling points of this service). With this service, you are assigned a dedicated server. Your OS still runs on a hypervisor (Storm uses Xen), but the underlying hardware is not shared with any other virtual servers, and you thereby have the full resources of that server available (no CPU limits, disk or memory sharing).

The server model we chose as the performance comparison baseline is the dual processor Intel E5506 2.13 GHz (8 cores total) with 4 x 15K RPM SAS drives configured in hardware managed Raid 1+0. SAS 15K is one of the fastest storage interfaces with throughput up to 6 Gbp/s, and Raid 1+0 can improve performance using striping.

To use this server as the baseline we assigned it an aggregate IO Performance score (IOP) of exactly 100 points. Other server disk IO benchmark results were then compared to baseline results and assigned a relative score, where 100 is equal in performance, less than 100 worse, and greater than 100 better. For example, a server with a score of 50 scored 50% lower than the baseline server, while a server with a score of 125, scored 25% higher.

To compute the IOP, the results from each of the benchmarks is first calculated for the baseline server. Each benchmark has a weight for the overall aggregate score. The baseline server benchmark scores are the 100% mark for each of these weights (i.e. the baseline server receives the full weight of each benchmark for its IOP). Once the weights are calculated, they are then summed to create an aggregate score. This score is then compared with the aggregate score of the baseline server and use to produce the IOP.

Example IOP Calculation:

Baseline aggregate score = blogbench-read: 200/200; bonnie++: 100/100; dbench: 30/30; fio: 30/30; hdparm: 100/100; iozone: 200/200; tiobench: 30/30; Total aggregate score = 690

Baseline IOP = (690/690) * 100 = 100

Server X aggregate score = blogbench-read: 180/200; bonnie++: 80/100; dbench: 25/30; fio: 20/30; hdparm: 90/100; iozone: 175/200; tiobench: 28/30; Total aggregate score = 598

Server X IOP = (598/690) * 100 = 86.67

Benchmarks

We used a combination 7 disk IO performance benchmarks to create the IOP score. The following is a description of the benchmarks and corresponding weights use:

We credit the Phoronix Test Suite for making it easier to run the benchmarks. The tests above come from the Disk test suite (except for bonnie++). If you'd like to compare your own server to the baseline server in this post, you can install Phoronix and use the comparison feature when running your own IO benchmarks. The full baseline server results are available here (including the ID for comparison tests). The baseline server bonnie++ results are available here.

Results

The following results are divided into sections based on provider. If the provider has more than one data center, multiple tables are displayed one for each. Each table shows the server identifier, CPU architecture, memory (GB), storage description (if known) or size, the server price, and the IOP score.

AWS EC2

AWS EC2 servers can use either ephemeral or external Elastic Block Storage (EBS) storage. Regarding EBS, Amazon states "The latency and throughput of Amazon EBS volumes is designed to be significantly better than the Amazon EC2 instance stores in nearly all cases.". EBS is a block level off-instance storage, meaning it exists independent of the underlying host. Striping of multiple EBS volumes can be used to improve performance. We used a single EBS volume only (no striping or other performance enhancements).

Because EBS is off-instance, it has the advantage of added durability because if the host system fails the instance can be quickly restarted on another host (this is not automatic). EBS volumes are automatically replicated to prevent data loss due to failure of any single hardware component. EBS is billed at $0.10/GB/month + $0.10 per 1 million I/O requests. The prices below do not include EBS usage charges.

Amazon states that larger instances will see faster and more consistent throughput performance. We found this to be generally true, until we got into the m2 instances where larger instance performance increase was not apparent.

Following suit with the CPU benchmarks, we saw a notable difference in performance in the APAC region compared with instances of the same size in other regions.

We've noted the standard EC2 hourly pricing in the tables. EC2 also offers reserve pricing (pay a 1 or 3 year setup in exchange for significantly discounted hourly rates) and spot/bid pricing.

Amazon Web Services (AWS) [US East]
ID CPU Memory Storage Price IOP
m2.2xlarge Xeon X5550 2.67 4 cores 34.2 EBS 2.4/hr 96.88
m2.xlarge Xeon X5550 2.67 2 cores 17.1 EBS 0.5/hr 88.9
m2.4xlarge Xeon X5550 2.67 8 cores 68.4 EBS 2.4/hr 87.56
c1.xlarge Xeon E5410 2.33 8 cores 7 EBS 0.68/hr 70.88
m1.xlarge Xeon E5430 2.66 4 cores 15 EBS 0.68/hr 57.03
m1.large Xeon E5430 2.66 2 cores 7.5 EBS 0.34/hr 53.01
c1.medium Xeon E5410 2.33 2 cores 1.7 EBS 0.17/hr 34.82
m1.small Opteron 2218 2.60 1 core 1.7 EBS 0.085/hr 22.2

Amazon Web Services (AWS) [US West]
ID CPU Memory Storage Price IOP
m2.xlarge Xeon X5550 2.67 2 cores 17.1 EBS 0.57/hr 104.36
m2.2xlarge Xeon X5550 2.67 4 cores 34.2 EBS 1.34/hr 97.87
m2.4xlarge Xeon X5550 2.67 8 cores 68.4 EBS 2.68/hr 89.56
c1.xlarge Xeon E5410 2.33 8 cores 7 EBS 0.76/hr 59.53
m1.xlarge Xeon E5430 2.67 4 cores 15 EBS 0.76/hr 58.45
m1.large Xeon E5430 2.66 2 cores 7.5 EBS 0.38/hr 49.11
c1.medium Xeon E5410 2.33 2 cores 1.7 EBS 0.19/hr 38.65
m1.small Xeon E5430 2.66 1 core 1.7 EBS 0.095/hr 26.47

Amazon Web Services (AWS) [EU West]
ID CPU Memory Storage Price IOP
m2.2xlarge Xeon X5550 2.67 4 cores 34.2 EBS 1.34/hr 92.66
m2.xlarge Xeon X5550 2.67 2 cores 17.1 EBS 0.57/hr 91.82
m2.4xlarge Xeon X5550 2.67 8 cores 68.4 EBS 2.68/hr 81.91
c1.xlarge Xeon E5410 2.33 8 cores 7 EBS 0.76/hr 71.31
m1.large Xeon E5430 2.67 2 cores 7.5 EBS 0.38/hr 54.81
m1.xlarge Xeon E5430 2.67 4 cores 15 EBS 0.76/hr 54.48
c1.medium Xeon E5410 2.33 2 cores 1.7 EBS 0.19/hr 35.98
m1.small Xeon E5430 2.66 1 core 1.7 EBS 0.095/hr 22.28

Amazon Web Services (AWS) [APAC]
ID CPU Memory Storage Price IOP
m2.2xlarge Xeon X5550 2.67 4 cores 34.2 EBS 1.34/hr 81.59
m2.4xlarge Xeon X5550 2.67 8 cores 68.4 EBS 2.68/hr 80.81
m2.xlarge Xeon X5550 2.67 2 cores 17.1 EBS 0.57/hr 76.44
c1.xlarge Xeon E5410 2.33 8 cores 7 EBS 0.76/hr 68.68
m1.large Xeon E5430 2.67 2 cores 7.5 EBS 0.38/hr 66.12
m1.xlarge Xeon E5430 2.67 4 cores 15 EBS 0.76/hr 57.47
c1.medium Xeon E5410 2.33 2 cores 1.7 EBS 0.19/hr 35.43
m1.small Xeon E5430 2.67 1 core 1.7 EBS 0.095/hr 27.89

Rackspace Cloud

Rackspace Cloud uses local storage for cloud servers. This provides generally good performance on nodes of all sizes. However, the tradeoff is that it does not provide durability should the host system fail. Rackspace does offers scheduled hot backup/imaging capabilities for added durability.

Rackspace Cloud [Dallas]
ID CPU Memory Storage Price IOP
rs-16gb Opteron 2374 2.20 4 cores 16 620 GB 0.96/hr 86.75
rs-4gb Opteron 2374 2.20 4 cores 4 160 GB 0.24/hr 63.1
rs-2gb Opteron 2374 2.20 4 cores 2 80 GB 0.12/hr 57.91
rs-1gb Opteron 2374 2.20 4 cores 1 40 GB 0.06/hr 57.36

Rackspace Cloud [Chicago]
ID CPU Memory Storage Price IOP
rs-8gb-il Opteron 2374 2.20 4 cores 8 320 GB 0.48/hr 77.95
rs-16gb-il Opteron 2374 2.20 4 cores 16 620 GB 0.96/hr 74.43
rs-4gb-il Opteron 2374 2.20 4 cores 4 160 GB 0.24/hr 72.12
rs-2gb-il Opteron 2374 2.20 4 cores 2 80 GB 0.12/hr 56.33
rs-1gb-il Opteron 2374 2.20 4 cores 1 40 GB 0.06/hr 45.84

Storm on Demand

Storm offers a diverse range of cloud servers to chose from including traditional cloud servers and their new "bare metal" dedicated cloud servers. The row highlighted in green is the baseline server for the IOP metric in this post. The 48GB cloud server was the top performer at almost 70% faster than the baseline server! We aren't sure how they do this, but we do know that the Intel Westmere CPU it runs on is very high performing (it was also the top performer in the CPU benchmarks post), and most likely the storage components are very high end as well. To our knowledge, all Storm's cloud servers run off of local host storage. They offer automated daily backups and imaging for added durability.

Storm Cloud [MI, US]
ID CPU Memory Storage Price IOP
storm-48gb Xeon X5650 2.67 12 cores 45.9 1500 GB 1.37/hr 168.48
e5506x2-8gb Xeon E5506 2.13 8 cores 8 4 SAS Raid 10 261GB 0.48/hr 100
storm-8gb Xeon X3440 2.53 4 cores 7 600 GB 0.27/hr 96.94
storm-32gb Opteron 2378 2.40 8 cores 30.4 1500 GB 0.69/hr 90.99
e5506x2-8gb Xeon E5506 2.13 8 cores 8 4 SATA Raid 10 917GB 0.391/hr 90.3
x3440-8gb Xeon X3440 2.53 8 cores 8 2 SATA Raid 1 919GB 0.274/hr 78.62
amd2350x2-32gb Opteron 2350 2.00 8 cores 32 4 SATA Raid 10 1853GB 0.713/hr 77.61
storm-16gb Opteron 2350 2.00 4 cores 15.2 750 GB 0.34/hr 72.49
i5-750-4gb Intel i5 750 2.67 4 cores 4 2 SATA Raid 1 220GB 0.206/hr 69.47
storm-4gb Intel i5 750 2.67 2 cores 3.5 300 GB 0.14/hr 60.86
i5-750-2gb Intel i5 750 2.67 4 cores 2 1 200GB SATA No Raid 0.171/hr 49.76
e5506x2-4gb Xeon E5506 2.13 8 cores 8 1 453GB SATA No Raid 0.274/hr 48.37
e5506x2-4gb Xeon E5506 2.13 8 cores 8 2 SATA Raid 1 453GB 0.322/hr 46.8
storm-2gb Intel Q9400 2.66 1 core 1.7 150 GB 0.07/hr 34.95

GoGrid

GoGrid's disk IO performance was excellent across instances of all sizes. Even the low end 1GB cloud server scored almost 10% faster than the baseline. The 4GB cloud server was the #2 performer in this post at over 60% better performance than the baseline. GoGrid's cloud servers run off of local host storage. They offer prepaid plans starting at $199/mo which discounts usage to $0.08/GB/hr (versus non-prepaid $0.19/GB/hr).

GoGrid [CA, US]
ID CPU Memory Storage Price IOP
gg-4gb Xeon E5520 2.27 4 cores 4 240 GB 0.76/hr 161.14
gg-2gb Xeon E5520 2.27 2 cores 2 120 GB 0.38/hr 133.61
gg-8gb Xeon E5450 2.99 6 cores 8 480 GB 1.52/hr 130.68
gg-1gb Xeon E5520 2.27 1 core 1 60 GB 0.19/hr 108.19

Voxel

Voxel's cloud server storage resides on external SANs in each data center. Disk IO performance was roughly 50% of the baseline across the board, about average for providers using external instance storage. The exact technical details of Voxel's SAN storage are not available.

Voxel [New York]
ID CPU Memory Storage Price IOP
vx-4gb-ny Xeon L5520 2.26 2 cores 4 40 GB 0.211/hr 49.65
vx-2gb-ny Xeon L5520 2.26 1 core 2 20 GB 0.106/hr 41.9
Voxel [Amsterdam]
ID CPU Memory Storage Price IOP
vx-2gb-nl Xeon L5520 2.26 1 core 2 20 GB 0.106/hr 40.61
Voxel [Singapore]
ID CPU Memory Storage Price IOP
vx-4gb-sg Xeon L5520 2.26 2 cores 4 40 GB 0.211/hr 51.52
vx-2gb-sg Xeon L5520 2.26 1 core 2 20 GB 0.106/hr 43.49

NewServers

NewServers offers a true bare metal cloud. When you create a server instance it actually deploys onto physical hardware including local disk storage (no hypervisor overhead). Like the baseline server, the ns-fast instance below uses SAS storage. According to NewServers, the SAS drives used in this instance are Seagate 10K RPM. The slower spindle speed and Raid 1 configuration may have attributed to the reduced performance of that server compared with the baseline.

NewServers [FL, US]
ID CPU Memory Storage Price IOP
ns-jumbo Xeon E5504 2.00 8 cores 48 2 x 500GB SATA RAID 1 0.6/hr 84.15
ns-fast Xeon E5450 2.99 4 cores 4 2 x 300GB SAS RAID 1 0.53/hr 51.97
ns-large Xeon E5405 2.00 4 cores 4 1 x 250GB SATA 0.25/hr 41.17
ns-med Opteron 3.20 2 cores 2 2 x 73GB SCSI Raid 1 0.17/hr 29.42
ns-small Opteron 2.80 1 core 1 1 x 36GB SCSI 0.11/hr 22.79

Linode

Linode markets itself as a VPS provider. However, because they are a very common and popular provider, and support some cloud-like features, we included them in our benchmarks. Linode uses Raid 1 local storage. The higher end servers generally performed better. The ln-14400 performed slightly better than the baseline server.

Linode VPS Hosting [Atlanta]
ID CPU Memory Storage Price IOP
ln-14400 Xeon L5520 2.27 4 cores 14.06 640 GB 26.67/day 106.06
ln-5760 Xeon L5520 2.27 4 cores 5.54 256 GB 10.67/day 96.21
ln-8640 Xeon L5520 2.27 4 cores 8.45 383 GB 16/day 95.38
ln-2880 Xeon L5520 2.27 4 cores 2.81 128 GB 5.33/day 47.17
ln-1080 Xeon L5520 2.27 4 cores 1.05 48 GB 2/day 34.47

SoftLayer

SoftLayer's cloud server storage resides on external SANs. Disk IO performance ranged from OK to painfully slow and showed a general increase in performance on larger sized instances. We believe storage is based on a GigE iSCCI SAN.

SoftLayer [Dallas]
ID CPU Memory Storage Price IOP
sl-2gb-dallas Xeon X3460 2.80 2 cores 2 100 GB 0.25/hr 41.07
sl-4gb-dallas Xeon E5520 2.27 4 cores 4 100 GB 0.35/hr 31.22
sl-1gb-dallas Xeon X3460 2.80 1 core 1 100 GB 0.15/hr 22.6

SoftLayer [WDC]
ID CPU Memory Storage Price IOP
sl-4gb-wdc Xeon X3460 2.80 4 cores 4 100 GB 0.35/hr 51.07
sl-2gb-wdc Xeon X3460 2.80 2 cores 2 100 GB 0.25/hr 41.53
sl-1gb-wdc Xeon X3460 2.80 1 core 1 100 GB 0.15/hr 19.33

SoftLayer [Seattle]
ID CPU Memory Storage Price IOP
sl-4gb-seattle Xeon X3460 2.80 4 cores 4 100 GB 0.35/hr 49.49
sl-2gb-seattle Xeon X3460 2.80 2 cores 2 100 GB 0.25/hr 39.74
sl-1gb-seattle Xeon X3460 2.80 1 core 1 100 GB 0.15/hr 24.89

Terremark

Terremark is a VMWare vCloud provider. Terremark was the best performing provider in this post using external SAN storage and providing automatic failover capabilities. Use of the SAN and VMWare provide a high availability feature wherein servers are automatically migrated to another host should the existing host fail.

Terremark vCloud Express [FL, US]
ID CPU Memory Storage Price IOP
tm-8gb-4vpu Opteron 8389 2.91 4 cores 8 80 GB 0.64/hr 117.5
tm-16gb-8vpu Opteron 8389 2.91 8 cores 16 160 GB 1.672/hr 101.85
tm-4gb-2vpu Opteron 8389 2.91 2 cores 4 40 GB 0.305/hr 95.86
tm-2gb Opteron 8389 2.91 1 core 2 20 GB 0.137/hr 88.99
tm-1gb Opteron 8389 2.91 1 core 1 10 GB 0.074/hr 74.68

OpSource Cloud

OpSource is another VMWare-based provider. Cloud server storage resides on an external SAN. Performance was generally slower than other SAN/VMWare providers in this post. Performance was roughly flat across instances of all sizes.

OpSource Cloud [VA, US]
ID CPU Memory Storage Price IOP
os-2gb Xeon X7460 2.66 1 core 2 20 GB 0.296/hr 42.98
os-16gb-4cpu Xeon X7460 2.66 4 cores 16 160 GB 0.808/hr 40.84
os-32gb-4cpu Xeon X7460 2.66 4 cores 32 320 GB 1.256/hr 40.73
os-8gb-4cpu Xeon X7460 2.66 4 cores 8 80 GB 0.584/hr 39.75
os-4gb-2cpu Xeon X7460 2.66 2 cores 4 40 GB 0.392/hr 38.24
os-1gb Xeon X7460 2.66 1 core 1 10 GB 0.268/hr 37.34

Speedyrails

Speedyrails is a VPS provider based out of Quebec Canada. Cloud server storage is local to the host.

Speedyrails [QC, CA]
ID CPU Memory Storage Price IOP
sr-4gb Xeon E5520 2.27 8 cores 4 160 GB 8/day 66.72
sr-2gb Xeon E5520 2.27 8 cores 2 80 GB 4.27/day 57.99
sr-1gb Xeon E5520 2.27 8 cores 1 40 GB 2.27/day 33.43

Zerigo

Zerigo is a VPS and Cloud Server vendor based out of Denver, CO. Cloud server storage is local to the host.

Zerigo [CO, US]
ID CPU Memory Storage Price IOP
zr-4gb Opteron 2374 2.20 4 cores 4 160 GB 0.24/hr 52.64
zr-2gb Opteron 2374 2.20 4 cores 2 80 GB 0.12/hr 42.2
zr-1gb Opteron 2374 2.20 4 cores 1 40 GB 0.06/hr 29.12

ReliaCloud

ReliaCloud uses an external SAN for cloud server instance storage. Average performance was slower than other external storage providers.

ReliaCloud Cloud Services [MN, US]
ID CPU Memory Storage Price IOP
rc-8gb 8 800 GB 0.64/hr 29.82
rc-2gb Xeon E5504 4.40 2 cores 2 200 GB 0.16/hr 27.41
rc-1gb Xeon E5504 2.00 1 core 1 100 GB 0.08/hr 23.83
rc-4gb Xeon E5504 2.00 4 cores 4 400 GB 0.32/hr 23.32

IBM SmartCloud

IBM SmartCloud also uses SAN storage. Disk IO performance was about average compared with other external storage providers.

IBM Development & Test Cloud [NY, US]
ID CPU Memory Storage Price IOP
ibm-dev-large Xeon X5570 2.93 8 cores 3.5 30 GB 56.53
ibm-dev-med Xeon X5570 2.93 4 cores 1.75 20 GB 51.82

BlueLock

BlueLock is a VMWare vCloud provider. Server storage resides on a SAN. Combined SAN and VMWare provide a high availability feature wherein servers are automatically migrated to another host should the existing host fail. Performance was very good for external storage providers and generally showed a linear increase in performance on larger sized instances.

BlueLock [IN, US]
ID CPU Memory Storage Price IOP
bl-8gb-4cpu Xeon X5550 2.67 4 cores 8 160 GB 0.661/hr 71.68
bl-16gb-8cpu Xeon X5550 2.67 8 cores 16 320 GB 1.729/hr 62.49
bl-4gb-2cpu Xeon X5550 2.67 2 cores 4 80 GB 0.308/hr 54
bl-2gb Xeon X5550 2.67 1 core 2 40 GB 0.134/hr 41.35
bl-1gb Xeon X5550 2.67 1 core 1 20 GB 0.068/hr 25.75

CloudCentral

Cloud Central is a new cloud server provider in Australia. Cloud Central uses SAN storage. Performance was very good compared with other SAN providers.

Cloud Central [AU]
ID CPU Memory Storage Price (AUD) IOP
cc-large Opteron 2374 2.20 4 cores 8 512 GB 0.96/hr 77.11
cc-huge Opteron 2374 2.20 4 cores 16 1024 GB 1.92/hr 73.77
cc-reg Opteron 2374 2.20 4 cores 4 256 GB 0.48/hr 68.53
cc-med Opteron 2374 2.20 4 cores 2 128 GB 0.24/hr 62.42
cc-small Opteron 2374 2.20 4 cores 1 64 GB 0.12/hr 44.27

RimuHosting

RimuHosting is a VPS provider based out of New Zealand. Cloud server storage is local to the host.

RimuHosting [NZ]
ID CPU Memory Storage Price (NZD) IOP
rh-nz-2gb Xeon E5506 2.13 2 cores 2 16 GB 210.88/mo 38.47

ElasticHosts

ElasticHosts is a UK cloud provider. We are unaware if storage is local or external.

ElasticHosts [UK]
ID CPU Memory Storage Price (GBP) IOP
eh-8gb-20gh Xeon E5420 2.50 6 cores 8 80 GB 0.654/hr 57.91
eh-4gb-8gh Xeon E5420 2.50 4 cores 4 40 GB 0.326/hr 33.06
eh-2gb-4gh Xeon E5420 2.50 2 cores 2 20 GB 0.164/hr 31.25
eh-1gb-2gh Xeon E5420 2.50 1 core 1 10 GB 0.082/hr 23.1

Flexiscale

Flexiscale is a UK cloud provider that has been around for a few years. They were recently acquired and renamed to Flexiant. They have recently released version 2.0 of their cloud server platform. They use external SAN storage.

8/17/2010 Update: Since originally conducting these tests in May 2010, Flexiscale has updated their external storage system. The top 8gb instance in the table below represents benchmark results conducted after than update. These results show a dramatic increase in IO performance (about 35%).

Flexiscale [UK]
ID CPU Memory Storage IOP
8gb AMD Opteron 8356 2.29 GHz [1 processor, 4 cores] 8 320 GB 84.93
8gb AMD Opteron 8218 2.62 GHz [1 processor, 4 cores] 8 320 GB 62.71
4gb AMD Opteron 8220 2.80 GHz [1 processor, 2 cores] 8 160 GB 41.77
2gb AMD Opteron 8218 2.60 GHz [1 processor, 1 core] 8 80 GB 36.56
1gb AMD Opteron 8218 2.60 GHz [1 processor, 1 core] 8 40 GB 19.46

Summary

This is our first attempt at comparing cloud provider disk IO performance. We acknowledge that it is not perfect and hope to make improvements over time. Please comment on this post if you have any suggestions on how we might improve our methods. We intend to continually run these benchmarks (every couple of months) to incorporate new providers, improve the quality and quantity of our data available, and check for provider upgrades and improvements.

Providers were about evenly split between those using external SAN storage versus those using local host storage for cloud server instance storage. Generally the local storage providers performed better in the benchmarks. However, most of the external SAN providers are able to incorporate better durability including implicit backups and automatic host server failover.