Is HDD Configured in RAID a Viable Alternative to SSD?

[FforRespekt]

My question is summarized in the title.  SSD's are pretty expensive for my budget so I've been wondering if I can mimic the performance of one SSD by buying a few high capacity HDDs and configuring them in RAID 0 or RAID 5.  Please keep in mind I'm a novice so explain any tech terms you have to use.  Thanks for the advice!

 

Edit:  Looks like I'm saving up for an SSD.  Thanks for the quick feedback!

[atxcyclist]

How much space are you looking for? 

[Kisai]

1 minute ago, FforRespekt said:

My question is summarized in the title.  SSD's are pretty expensive for my budget so I've been wondering if I can mimic the performance of one SSD by buying a few high capacity HDDs and configuring them in RAID 0 or RAID 5.  Please keep in mind I'm a novice so explain any tech terms you have to use.  Thanks for the advice!

 Nope.

 

A SSD is 550MB/sec. To get that same READ performance you would need at least 4, if not 5 drives in Raid 1 configuration. NVME SSD is more 2-3 times faster, and most MB's don't have enough SATA ports to pull that off.

 

A Raid 0 configuration will not improve your performance, and neither will Raid 5. The write speed will remain the same regardless of configuration.

[Radium_Angel]

3 minutes ago, FforRespekt said:

Thanks for the advice!

Nope, I have several SAS RAID 5 arrays in my main server, and while quick, nowhere near the speed of a good SSD

[Windows7ge]

No. Seek time or IOPS in the case of SSDs are what you will notice more over sheer bandwidth. Although RAID10 can greatly increase IOPS even a single SSD can still surpass a sizable RAID10 array.

[Roswell]

Just now, Kisai said:

 Nope.

 

A SSD is 550MB/sec. To get that same READ performance you would need at least 4, if not 5 drives in Raid 1 configuration. NVME SSD is more 2-3 times faster, and most MB's don't have enough SATA ports to pull that off.

 

A Raid 0 configuration will not improve your performance, and neither will Raid 5. The write speed will remain the same regardless of configuration.

Concurrent read speeds aren't what make them faster in general, it's random seeking times. You could strangle an SSD down to 100MB/s and it would still walk all over a mechanical drive.

[Kisai]

2 minutes ago, Vitamanic said:

Concurrent read speeds aren't what make them faster in general, it's random seeking times. You could strangle an SSD down to 100MB/s and it would still walk all over a mechanical drive.

Yeah, a SSD will totally stomp any mechanical drive RAID array, regardless of how many drives it has.

 

[dalekphalm]

10 minutes ago, FforRespekt said:

My question is summarized in the title.  SSD's are pretty expensive for my budget so I've been wondering if I can mimic the performance of one SSD by buying a few high capacity HDDs and configuring them in RAID 0 or RAID 5.  Please keep in mind I'm a novice so explain any tech terms you have to use.  Thanks for the advice!

No.

 

RAID0 will increase your sequential read/write speeds a bit - not quite double. But random reads/writes are still going to be slow AF. An SSD will crush even the fastest HDD's in RAID0.

 

RAID5 is just straight up slower than a regular HDD, let alone an SSD. RAID5 has to calculate and then write to disk the parity information for every single file write. This means every write is slower because of it.

[Bombastinator]

3 minutes ago, FforRespekt said:

My question is summarized in the title.  SSD's are pretty expensive for my budget so I've been wondering if I can mimic the performance of one SSD by buying a few high capacity HDDs and configuring them in RAID 0 or RAID 5.  Please keep in mind I'm a novice so explain any tech terms you have to use.  Thanks for the advice!

The problem is HDDs arent just slower than SSDs they’re a lot slower, and as you increase the size of a RAID you increase its fragility. The fastest HDs are half the speed of the slowest SSDs, and a fifth the speed of the fastest ones which can bury sata6. These faster ones are getting pretty common these days so it’s a lot more like the 1/5th than 1/2 these days.

Every time you double the number of drives in Raid0 you double the read/write while either doubling or quadrupling fragility (depending on how you count it)  So, sort of.  I’m not sure it would actually be cheaper though unless you have access to a large number of free fast HDDs.
Here’s a link to an article that talks about it. The article is out of date, but it gets the concepts across. 

https://tekhattan.com/blog/hardware/ssd-vs-hdd-speed-lifespan-and-reliability/

[Bombastinator]

10 minutes ago, Kisai said:

 Nope.

 

A SSD is 550MB/sec. To get that same READ performance you would need at least 4, if not 5 drives in Raid 1 configuration. NVME SSD is more 2-3 times faster, and most MB's don't have enough SATA ports to pull that off.

 

A Raid 0 configuration will not improve your performance, and neither will Raid 5. The write speed will remain the same regardless of configuration.

This makes me think I might be confusing raid0 and raid1.  One of them is a straight data stripe that doubles throughout but drastically increases fragility.

[Sauron]

No, it would be faster than just a single HDD but not nearly as fast as an ssd.

14 minutes ago, FforRespekt said:

SSD's are pretty expensive for my budget

What is your budget? 120GB SSDs go for around $30, is that really too much for you?

[dalekphalm]

3 minutes ago, Bombastinator said:

This makes me think I might be confusing raid0 and raid1.  One of them is a straight data stripe that doubles throughout but drastically increases fragility.

RAID1 is mirror - data is written to both. Read speeds can be increased, if the controller is smart enough (it can grab data from both drives at once).

 

RAID0 is stripe - data is split up and spread across both drives (no redundancy). Because you're reading and writing from both, you do get a performance boost in both cases - and usually a bigger one compared to RAID1 reads (if there's a boost at all for RAID1).

[dalekphalm]

4 minutes ago, Sauron said:

No, it would be faster than just a single HDD but not nearly as fast as an ssd.

What is your budget? 120GB SSDs go for around $30, is that really too much for you?

Agreed - frankly, even an ultra-low budget new PC Build should include an SSD these days.

[Kisai]

12 minutes ago, Bombastinator said:

This makes me think I might be confusing raid0 and raid1.  One of them is a straight data stripe that doubles throughout but drastically increases fragility.

Raid 0, is basically not that different from JBOD. So at best Raid 0 is the same performance as the slowest drive in the array. No drive failures are permitted. The only theoretical performance increase comes from a read/write setup that permits reading to and writing different data to both drives at the same time, and that is almost never the case unless the file system is super fragmented and therefor already rather degraded. If you want a performance increase without redundancy you would be better off just having JBOD and mounting each drive as it's own drive letter/mount point, and splitting up your OS, applications, page/swap/temp files accross them all. Even then it's getting stomped by a SSD.

 

Raid 1, is a mirror, so you double the read performance, but the write performance will never be faster than the slowest drive in the array because you double the amount of writing that goes on, split between two drives. You can lose one or the other drive but not both in a 2-drive system. When there are more drives, you increase the read speed, but not the write speed, but do increase the redundancy so you can afford to lose more than one drive then. RAID 5 and 6 the write speed is divided by the number of drives. So those options are usually nonviable.

[dalekphalm]

2 minutes ago, Kisai said:

Raid 0, is basically not that different from JBOD.

JBOD and RAID0 have some crucial differences.

 

JBOD just stacks drives together. Files are typically stored in their entirety on a single drive. You also typically get all the space from all the drives in the JBOD (including if there are drives of varying sizes).

 

RAID0 splits the files into chunks and stripes the file onto both (or more) drives. RAID0 will also treat every drive as the size of the smallest drive (if they are different sizes).

2 minutes ago, Kisai said:

So at best Raid 0 is the same performance as the slowest drive in the array.

This is entirely false. I think you mean RAID1 here.

RAID0 gets a speed boost for every drive you drop into the array. However, there is a kernel of truth in there:

Drives of different speeds will cause performance losses.

 

Scenario 1:

Drive 1 (speed 100%)

Drive 2 (Speed 80%)

RAID0 with both drives: speed 180%

 

Scenario 2:

Drive 1 (speed 100%)

Drive 2 (speed 100%)

RAID0 with both drives: speed 200%

 

Disclaimer, the actual speeds are arbitrary for example purposes only

 

Point being is that a slower drive can slow down the potential of the RAID0 array, but won't actually limit performance to that drives speed.

2 minutes ago, Kisai said:

No drive failures are permitted. The only theoretical performance increase comes from a read/write setup that permits reading to and writing different data to both drives at the same time, and that is almost never the case unless the file system is super fragmented and therefor already rather degraded.

This is correct.

2 minutes ago, Kisai said:

Raid 1, is a mirror, so you double the read performance

You can double the read performance. It highly depends on the controller used though. And RAID0 has essentially this exact same benefit as well.

2 minutes ago, Kisai said:

, but the write performance will never be faster than the slowest drive in the array because you double the amount of writing that goes on, split between two drives.

Correct - the write performance of RAID1 is essentially that of the individual drives. No boost. You could take a performance hit though if the drives are mismatched and one is slower than the other.

2 minutes ago, Kisai said:

You can lose one or the other drive but not both in a 2-drive system. When there are more drives, you increase the read speed, but not the write speed, but do increase the redundancy so you can afford to lose more than one drive then.

Yep - though realistically no one does RAID1 with more than 2 disks unless there's some crazy redundancy requirements going on.

2 minutes ago, Kisai said:

RAID 5 and 6 the write speed is divided by the number of drives. So those options are usually nonviable.

Ehhh this isn't really correct. The write speed is nearly the same as each individual drive combined (like RAID0) - it's slightly worse though because of the parity write. You essentially lose the performance from the Parity write, but a RAID5 with 4 drives is generally faster in writes than a single drive of the same type.

[Thirdgen89GTA]

3 hours ago, FforRespekt said:

My question is summarized in the title.  SSD's are pretty expensive for my budget so I've been wondering if I can mimic the performance of one SSD by buying a few high capacity HDDs and configuring them in RAID 0 or RAID 5.  Please keep in mind I'm a novice so explain any tech terms you have to use.  Thanks for the advice!

 

Edit:  Looks like I'm saving up for an SSD.  Thanks for the quick feedback!

Absolutely not.  SSD's biggest boon is its Random IO and latency performance.  Two areas where striping spinning rust won't gain you anything (it actually increases latency because both disks must spin up and start seeking).  But you do see a minor increase in IO performance.

 

That said, depending on your setup you can use a SSD cached spinning disk.  Both Intel, and AMD offer software solutions to create a tiered storage system.

 

The Intel one was good, the AMD one was poor.  And Linus did test a 3rd party solution Primo Cache which worked very well.

 

 

[Robchil]

Never use RAID 1 on average consumer system you play games on. it wills stop every 5 minutes with 2-4 second freeze while it waits to sync the other drive, if you are using HDD. 

 

[Thirdgen89GTA]

44 minutes ago, Robchil said:

Never use RAID 1 on average consumer system you play games on. it wills stop every 5 minutes with 2-4 second freeze while it waits to sync the other drive, if you are using HDD. 

 

No it won't.  Maybe if you have a crap software solution. But a good software solution, or a true Raid card will handle all of the replication and parity without a hiccup to the user.

[dalekphalm]

On 2/21/2020 at 7:29 AM, Robchil said:

Never use RAID 1 on average consumer system you play games on. it wills stop every 5 minutes with 2-4 second freeze while it waits to sync the other drive, if you are using HDD. 

Perhaps if you're using mismatched HDD's, that might be an issue.

On 2/21/2020 at 8:15 AM, Thirdgen89GTA said:

No it won't.  Maybe if you have a crap software solution. But a good software solution, or a true Raid card will handle all of the replication and parity without a hiccup to the user.

To be fair, a RAID Card isn't exactly a "consumer" part - but never the less, you're correct. A good RAID1 system won't have any issues like freezes.

[Bombastinator]

3 minutes ago, dalekphalm said:

Perhaps if you're using mismatched HDD's, that might be an issue.

To be fair, a RAID Card isn't exactly a "consumer" part - but never the less, you're correct. A good RAID1 system won't have any issues like freezes.

Moreso than they used to be in that a lot of consumer motherboards come with built in hardware RAID.

[Thirdgen89GTA]

Most if not all consumer gamer mobos have some form of RAID0/1/5 support now. you just need a f6 driver so you can install Windows onto a RAID boot volume. 
 

as for software I’ve used storage spaces in a pinch for mirrored data volumes. Not great but all I had available for free at times. 
 

 

I run FreeNAS at home and that’s pure software. ZFS is better than some actual raid cards at that. 
 

 

[Bombastinator]

To recap:  the OP question was one part but had three aspects:

 

Q: Can RAID be used to achieve SSD level bandwidth? 
A: Yes. Barely. With a bunch of effort.

 

Q: Is doing such a thing “viable”?

A: At best, sort of.  There are numerous complications.

 

Q: Is it cheaper than using an SSD?

A: In almost all home user situations, No.  Not even close.  There may be some unusual edge situation involving very high storage amounts or unreasonably cheap HDs where such a thing might become possible.