Hot answers tagged

175

This is going to be a function of your workload and the class of drive you purchase... In my server deployments, I have not had a properly-spec'd SSD fail. That's across many different types of drives, applications and workloads. Remember, not all SSDs are the same!! So what does "properly-spec'd" mean? If your question is about SSD use in enterprise ...


95

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 said, each one has specific benefits. SSD's almost always have a higher Cost-per-Byte. I can get 10k SAS 4kn HDD's with a cost-per-gigabyte of $0.068/GB USD. ...


60

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). To give you some ballpark numbers (on old 34nm tech): SLC drive: 100K P/E cycles (program-erase cycles), 100 GB in size, 10 DWPD (Drive Writes Per Day) x 5y, ...


59

Every laptop at my work has either a SSDs or Hybrid since 2009. My SSD experience in summary: What I'll call "1st Generation" drives, sold around 2009 mostly: In the first year about 1/4 died, almost all from Syndrome of Sudden Death (SSD - It's funny, laugh). This was very noticeable to end users, and annoying, but the drastic speed difference made this ...


53

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 same time, and therefore tend to get to the far end of the bathtub curve and start dying at about the same time. In that sense, buying from different vendors is ...


50

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 tool specifically designed for SSDs, which can use the drive's internal flash erase (discard) to discard all of the blocks, including the ones you can't access. ...


35

Drive manufacturers specify the reliability of their products in terms of two related metrics: the annualized failure rate (AFR), which is the percentage of disk drives in a population that fail in a test scaled to a per year estimation; and the mean time to failure (MTTF). The AFR of a new product is typically estimated based on accelerated life and stress ...


26

I've covered SSD interoperability and compatibility issues with HP servers several times here. Check these posts: HP D2700 enclosure and SSDs. Will any SSD work? Are there any SAN vendors that allow third party drives? So, the move from G6 and G7 HP ProLiants to the Gen8 variants forced a disk carrier form-factor change. HP went to the SmartDrive carrier ...


26

Look for an industrial or ruggedized SSD for this application. A good example of a proper product spec. http://www.pretec.com/products/ssd-series/item/sata-ssd-series/a5000-industrial-grade .Standard 2.5" SATA III SSD, compatible with SATA III/II/I interface .Capacity: 32GB ~ 256GB .Data transfer rate: Up to 490 MB/s .Built-in ECC (Error Correction Code) ...


26

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 consumer-grade drive usually have quite good performance consistency values (but you need to avoid the drives which, instead, choke on sustained writes). ...


25

I was struggling with the same problem on my notebook, but as I reboot it pretty much on a daily basis, the accepted answer wasn't helpful. I have a Samsung mSATA SSD, which happens to have the SMART attribute #241 Total_LBAs_Written. According to the official documentation, To calculate the total size (in Bytes), multiply the raw value of this attribute ...


25

I would use an industrial IDE SSD...(another option). It doesn't sound like you need much space, and there are SSDs made specifically for this purpose. I would NOT bother with IDE adapters and consumer-level SSDs for this application. If you do go for compact flash, again, try something that's purpose-built for the application.


25

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. EBS are more flexible, since you can attach and detach it from instances, but is a little bit slower, as more suitable for general purpose. Now, in Step 4, you ...


22

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 works on an LSI controller should be okay. Your ability to monitor the health of your RAID array is paramount. Since this is Dell, ensure you have the ...


20

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 serial workload, as new writes can not be queued before the previous write was committed and confirmed. In other word, writes submission rate strictly depend on ...


19

Does it have to be a SATA SSD? CompactFlash cards are pin-for-pin compatible with the ATA standard 1. Which means you can use a passive electrical adapter to connect one to an IDE cable (or two!). Would this give you enough space (I've seen some mahoosive CF cards...), I wonder. It'd give you the reliability of solid state memory, and the oldness of ...


19

Unfortunately the MTBF isn't what most people think... It is not how long an individual drive will last. Manufacturers expect their drives to last as long as the warranty, after that it really isn't their problem. Older electromagnetic platter hard drives will seize up after 10 or so years. Integrated circuits last an extremely long time, but other ...


18

In my experience, the real problem are the dying controllers, not the flash memory itself. I've installed around 10 Samsung SSDs (830, 840 [not pro]) and none of them has made any problems so far. The total opposite are drives with Sandforce controllers, i had several problems with OCZ agility drives, especially freezes in irregular time intervals, where the ...


18

The on-device redundancy should do the job just fine for failures of the flash chips - analogous to RAID among all of the components doing actual data storage. Should I be concerned about Fusion-io failure any more than I'd be concerned about a RAID controller failure or a motherboard failure? A failure of the entire device would be pretty much analogous ...


18

ATA Secure Erase is part of the ATA ANSI specification and when implemented correctly, wipes the entire contents of a drive at the hardware level instead of through software tools. Software tools over-write data on hard drives and SSDs, often through multiple passes; the problem with SSDs is that such software over-writing tools cannot access all the storage ...


18

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 retention than SSDs too. Also when SSDs die they tend to die completely, all in one go, whereas HDDs tend to die in a more predictable way that maybe allows more time ...


17

Short answer, since I don't see what problem you're looking to solve... If you can, use separate devices. This depends on the scale of your environment... If it's just a simple home system or a virtualized or an all-in-one ZFS solution, you can use a single device. In larger or high-performance ZFS solutions, I use devices suited specifically for their ...


17

Let's try to read 1000 random 4k blocks from first 16GB of a disk: time for i in `seq 1 1000`; do dd bs=4k if=/dev/sda count=1 skip=$(( $RANDOM * 128 )) >/dev/null 2>&1; done This is something that should be very slow on rotating drive in comparison with SSD. On my desktop class SSD it ends in about a second. On desktop class 7200rpm rotating ...


16

Ultimately, it comes down to your failure model. What is the impact of a failure? Historically, we've always RAIDed everything since the cost of doing so has been negligible. Another $500 for a drive for mirroring? Totally worth the cost without even considering it. When you're talking about another $10K+ to turn on mirroring, it needs a bit more ...


16

While the other answer here beings up some points, your specific issues are due to platform limitations and OS configuration: You're throughput-limited by the use of consumer SATA SSDs on an HP Smart Array P410 RAID controller. SATA disks run at 3.0Gbps (3G) on these controllers rather than 6.0Gbps (6G). So that's a barrier that impacts the read speeds of ...


16

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 write caches, performance should not vary much between the various options. On the other hand, there are other factors to consider: with hardware RAID is often ...


15

We don't proactively replace disks. Wait until they fail or report prefailure status. This is why you have (hardware) RAID, management agents, failure indication LEDs on the server and a monitoring solution. Keeping your gear under warranty and maintain your support contracts (within reason), having cold spares of components that fail often (disks, power ...


15

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 programmed. The first failure condition is obvious: without power protection, any data which are not on stable storage (ie: NAND itself) but on volatile cache ...


14

So, some research has been done on this. According to SSD researchers Michael Wei, Laura M. Grupp, Frederick E. Spada, and Steven Swanson, who presented the paper, "Reliably Erasing Data from Flash-Based Drives" (PDF warning), quote: ...our results lead to three conclusions: First, built-in commands are effective, but manufacturers sometimes ...


14

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 is read, random access means you're reading single parts of different files. If you look for a drive for database usage, you should look for: An enterprise, ...


Only top voted, non community-wiki answers of a minimum length are eligible