RAID with a SSD and HDD

It is a fact that the slowest component in the computer is the storage system. The CPU with its fast cache memory interacts with the fast RAM and the slower systems disks.

RAID, an acronym for Redundant Array of Independent/Inexpensive Disks is a method of putting together different disks into one to improve performance, reliability or both.

Since SSDs has currently taken over from mechanical hard drives, means that people may have to compare and contrast between HDD Raid Vs SSD Raid. Considering factors and their uniqueness, there is no winner here. You can judge for yourself after reading this article.

RAID Levels

Several so-called RAID “levels” are now so common that, though there is no universal standard for RAID configurations, these levels are the commonly accepted standards.

When comparing these two techniques, it’s important to recap the pros, cons, and number of drives you need for each type of RAID setup. Let’s go over them in short order:

• RAID 0 requires dual disks, gives no room for redundancy but has great speed and no disk space penalty.
• RAID 1 requires dual disks, allows redundancy, but only has low-speed gains and a 50% disk space penalty.
• RAID 10 requires four disks, provides redundancy, allows fast reads, greater write speeds, and allows for 50% of disk space.
• Note that we also have more complex RAID levels (e.g. 1E, 5, 50, 6 & 60) but the aforementioned three are the most common that most users would be interested in.

HDD RAID Vs a Single SSD

Since the most common reason people are interested about RAID and how it relates to SSDs comes from their comparison, we’ll deal with the comparison before delving into other things.

It’s common knowledge that Mechanical hard drives are really slow, so one well-known way of going around that problem of speed is by joining two identical drives into the RAID 0 configuration.

The data of those two are “striped” across both drives so they get to perform as one hard drive while the transfer speed goes twice as fast. Since each drive has a unique part of your data, each drive can contribute to any operation.

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In terms of raw speed, a single SSD constantly beats the RAID 0 hard drive setup. Even the costliest10,000 RPM SATA III consumer hard drive at its best speed only tops out at 200MB/s. in theory. So two of them in RAID0 can only manage a little under twice that.

Any SATA III SSD will get very close to the limit of the connection at 600MB/s. If we’re talking NVME SSDs using the PCIe protocol, then typical read speeds exceed 2000MB/s.

All in all, if high performance is what you’re interested in, a single SSD will always win over a pair of mechanical drives. Even if the pair are the fastest mechanical drives in the world.

This also applies in the aspect of reliability and data protection. Someone with a RAID 10 setup and four hard drives, will still get double the drive speed and in case of loss of drive, data will still be protected. Despite all the seeming advantages of a hard drive, a single SSD is still more reliable than the hard drive. With SSD you can overwrite data till it gets to its limit, then you will not be allowed to keep overwriting, but you can still read all the data on the disk.

Sudden failure of an SSD is rare, but to prevent it from ever happening, you can choose to run two SSD in RAID 1 and it is perfectly fine. The fact that data is protected even when SSD is irretrievably broken down is an added advantage.

It is not wise to spend money on a RAID 1 SSD setup only for data safety. The more economical thing to do is to back up your hard drive image to a cheap external drive or the cloud since most desktop systems are not mission-critical.

HDD RAID vs SSD RAID: General Considerations

Now that we’ve discussed the single SSD scenario, let’s move on to direct RAID-to-RAID comparisons. That is mechanical drives in RAID compared to SSDs in RAID. We have three main aspects under consideration: performance, price and data reliability. Let’s look at each one in detail.

Performance

It is common knowledge that an SSD RAID configuration outperforms any mechanical drive RAID setup. So the main factor to consider is how much performance you’ll gain from running SSDs in RAID and whether it’s worth it.

One of the factors to check is hardware versus software RAID. A dedicated hardware RAID controller will provide better performance than a software-based solution. Also worthy of note is the fact that an increase in speed, may mean a decline in other computer components.

You should note that there is little difference between SATA III SSD and an M.2 NVMe PCIe drive, despite the latter being five or six times faster.

So joining two SSDs in RAID 0 may not noticeably improve your user experience.

Price

SSD is a lot more pricey than the hard drive but for its performance, lots of people are willing to pay the price. Mechanical drives now try to increase capacity since they can’t win on performance level.

Reliability & Endurance

SSD endurance is something we’ve written about before and it’s a complex comparison with mechanical drives. SSDs wear out when they’ve been written to too much. However, for modern drives, write endurance is far beyond what most users will ever need.

Conclusion

This article has shown that there is nowhere to have a straight answer in the argument between HDD RAID or SSD RAID. Everything depends on your specific needs. Nevertheless, here are some general guidelines:

Most users won’t benefit from SSD RAID speed improvements.
HDD RAID is still best for mass storage.
SSDs are reliable enough to make RAID sensible only for mission-critical uses.

With a clear picture of where each approach works best, you should have a much better idea of which option makes the most functional and economic sense for you. Visit Amazon.com to see great products.