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98 votes

SSD or HDD for server

One aspect of my job is designing and building large-scale storage systems (often known as "SANs", or "Storage Area Networks"). Typically, we use a tiered approach with SSD's and HDD's combined. That ...
62 votes
Accepted

Does bigger capacity SSD have longer life due to wear leveling?

This is true, and it was one of the key motivation to backing the switch from SLC (fast and durable flash cells, but small capacity) to MLC (slower and less durable flash cells, but bigger capacity). ...
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55 votes
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What risks are there with mixing SSD models in RAID?

The single biggest thing that crosses my mind isn't SSD-specific: that the biggest danger with RAID is that all the devices in any given RAID are often purchased from the same manufacturer, at the ...
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50 votes
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Wipe is very slow. Too little entropy?

Don't attempt to "wipe" an SSD with tools designed for spinning magnetic hard drives. You won't actually destroy all the data, and you'll just reduce the lifetime of the SSD. Instead, use an erase ...
29 votes
Accepted

EBS vs SSD definition

SSD are faster because there's no network latency, but it is ephemeral and you can't detach it from an instance and attach it to another. As you can see, it is available to more powerful instances. ...
26 votes

What is the current state (2016) of SSDs in RAID?

Let's try to reply one question at a time: Is TRIM support necessary for modern (2015-2016 era) SSDs? Short answer: in most cases, no. Long answer: if you reserve sufficient spare space (~20%), even ...
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22 votes
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Consumer (or prosumer) SSD's vs. fast HDD in a server environment

Note: This answer is specific to the server components described in the OP's comment. Compatibility is going to dictate everything here. Dell PERC array controllers are LSI devices. So anything that ...
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20 votes
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Poor iSCSI performance with SSD disks and 10 Gbe network

Short answer: This is the results of network latency and a serial workload (as you imposed by using direct=1, sync=1 and iodepth=1). Long answer: using direct=1, sync=1 and iodepth=1 you created a ...
  • 45.1k
18 votes

SSD or HDD for server

HDD is still quite preferred Is it? I'm not sure it is to be honest. HDD's come in large sizes for a decent price right now, that's undeniable, and I think people trust them for longer data ...
  • 101k
17 votes
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Is there a way to protect SSD from corruption due to power loss?

When suddenly losing power, MLC/TLC/QLC SSDs have two failure modes: they lose the in-flight and in-DRAM-only writes; they can corrupt any data-at-rest stored in the lower page of the NAND cell being ...
  • 45.1k
16 votes
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Does a RAID controller with an NV cache improve the performance or integrity of an SSD array?

If used with SSDs without powerloss-protected write cache, the RAID controller's NVCACHE is extemely important to obtain good performance. However, as you are using SSDs with powerloss-protected ...
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14 votes
Accepted

When reading SSD drive specs, what's the difference between MB/s and IOPS?

MB/s states how many Megabytes per second the drive can handle as throughput. IOPS states how many single operations per seconds can be handled. Sequential access means that for example one big file ...
  • 1,091
13 votes

Optimize SSD storage on Centos 6.6 - KVM

TRIM works at the filesystem level so as you're giving your KVM domains a raw block device then you need to enable TRIM from within the domain; your host can't know the domains filesystem utilisation ...
  • 4,691
13 votes

Does a RAID controller with an NV cache improve the performance or integrity of an SSD array?

Q1: Are any of these configurations at risk for data loss or corruption on power loss? A1: You shouldn't have any issues, unless you'll configure cache in write-back mode, and w/out NV RAM. Q2: ...
13 votes

Does bigger capacity SSD have longer life due to wear leveling?

SSDs wear out when you use up their block erase cycles. Each block can only be erased so many times. Larger SSDs have more blocks, so that means more block erase cycles. All other things being equal, ...
12 votes

Poor write performance of software RAID10 array of 8 SSD drives

The measured low performance are the results of various factors: after creation the array is entirely synched, causing the allocation of most (if not all) flash data pages on half the SSDs. This will ...
  • 45.1k
12 votes

Tmpfs vs NVME SSDs from performance POV

tmpfs, being an extension of the pagecache, really operates as a "transparent" ramdisk. This means it provides very fast sequential read/write speed, but especially fast random IOPs (...
  • 45.1k
11 votes

For L2ARC and ZIL: is it better to have one large SSD for both, or two smaller SSDs?

There are some fundamental misconceptions from the outset about ZIL which need correcting before continuing. Understand this: Under "normal" circumstances, ZIL/SLOG is not touched. It's only ...
  • 111
11 votes

does adding heaps of drives to a raid 0 increase performance?

In theory yes, more drives in a raid0 would lead to higher performance because the load is shared over more drives. However in practice you would be limited by the the bandwidth of the raid controller,...
  • 4,560
11 votes

Does bigger capacity SSD have longer life due to wear leveling?

Yes, larger SSDs have higher endurance. There's a couple of factors involved here, and it's not as simple as it appears: Larger SSDs have more NAND inside them, and any half-decent SSD supports wear ...
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11 votes
Accepted

SSD IOPS on linux, DIRECT much faster than buffered, fio

Debian 7.11 with 3.2 kernel Upgrade if at all possible. Not only do you get kernel improvements, but Wheezy is end of life. Yes, you see higher utilization and queue depth when direct=1. The fio ...
11 votes

Is there a way to protect SSD from corruption due to power loss?

Yeah. Don't get super cheap SSD - anything outside the low end consumer market has capacitators and full protection against power loss. Amd really does not cost that much more.
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11 votes
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Offline uncorrectable sectors in SSDs being used for ZFS L2ARC?

Those numbers are obviously bogus. Your SSD doesn't have that many sectors at all, let alone offline uncorrectable ones. Check for firmware updates for your SSD that will fix the problem. Otherwise, ...
11 votes
Accepted

Can we upgrade Dell's basic Server R240 (which still uses HDD 7200RPM) to an SSD?

On Dell's R210, R220 and T130 I've successfully used Sandisk's consumer grade SSDs for years. I've done this with PERC's H410 and H710 controllers. It will be a matter of controller and controller's ...
  • 1,699
10 votes

EBS vs SSD definition

First of all, be aware of the difference between a root volume, an EBS and an EC2 instance store. The root volume is what hosts the EC2 instance's operating system and it's almost always an EBS ...
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10 votes
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Enable Discards HP 3PAR StoreServ 7400

Being able to run fstrim on the / partitions would be the best solution however with they way your ESXi is configured it would not be possible. You need to be able to enable discards on both the VM ...
10 votes
Accepted

Why do sequential writes have better performance than random writes on SSDs?

A reasonably concise explanation by Seagate (WayBack copy here) on how garbage collection is responsible for the difference in SSD performance for random versus sequential writes: ... the need for ...
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10 votes

Qemu TRIM and discard on a physical SSD device

Research Qemu treats discard=unmap and discard=on the same as you can see in its source code: block.c (L 1102): if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) It also seems to ...
10 votes
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Automatically mount SSD instance storage on AWS EC2 in Ubuntu 16.04

The 200GB SSD disk that you see is called Instance storage (or ephemeral storage) and is destroyed everytime you stop the instance and created new every time you start the instance. That means two ...
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10 votes
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With a 500GB SSD and a 250GB SSD is it possible to mirror a 250GB partition on the 500GB with the 250GB SSD using ZFS?

First things first: this is not a good idea. You should really use same-capacity disks, if possible. That said, what you ask is indeed possible: you need to partition both disks each with a ~250 GB ...
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