2x ssHd's in RAID - twice or half as effective SSD?

[Blue_Max]

A strange thought occurred to me (as they often do.) :twisted:

If one were to use a pair of Seagate SSHD drives in RAID, would their 8GB SSD caches work twice as well, no real difference, or only half as effective?

Just a random thought... but it could be a way to get large storage with impressive speeds (without breaking the bank, that is!)

 

[Elixer]

You are still stuck with the spindle speed & density of the platters, so you are still limited by those factors, so, no impressive speed will be found vs a "pure" SSD.

If you are asking, since both drives have the data split between them, then, each drive's cache would only read in 1/2 the amount it would normally have used, then, yeah, you can say that.

 

[Blue_Max]

Seagate says:
Can I use SSHD with RAID?

Yes you can, with excellent results, use Raid 0 and Raid 1 configurations. An SSHD in RAID 0, as compared to a single drive configuration, delivers performances as much as 70% higher.
Standard drives in RAID configuration should not be used with SSHD drives as this will nullify the benefits of using a hybrid drive.
Because current drives are not designed for multi-drive vibrations, they have not been tested with RAID 5, 6, or 10, and are not recommended.


...no one is saying they'll ever meet a pure SSD, but you also won't get 2TB of SSD for only $200. I'm just wondering how much better they'd be than mechanical drives, and how much would 2x1TB drives perform vs. 1x2TB SSHD drive...

Just a fun thought.

 

[glugglug]

I wouldn't say "twice" as effective, but probably significantly better in most cases than the single drive.

You are basically paying $50 extra for a SSHD vs. a regular HDD, plus paying another $50-100 to have your data split into 2 drives instead of 1.

You can get a 120GB SSD for boot/apps for $80-90, and use the leftover savings vs. 2 SSHDs to purchase a much larger HDD.

 

[Blue_Max]

Yeah... you'd have to need 1-2TB of "speedy" drive to justify it... I was simply wondering *IF*.

 

[Cerb]

Yeah... you'd have to need 1-2TB of "speedy" drive to justify it... I was simply wondering *IF*.

Nah, just get a nice 120GB SSD, on sale, for added cost-effectiveness, use it for SRT, and set SRT for maximal mode (I think that's what they call it), which does not guarantee write-through behavior. Add a UPS, and you'll, realistically, be golden. Even SRT in enhanced mode (regular, with write-through guarantees) will beat hybrid HDDs.

 

[Blue_Max]

I wish Intel would update their SRT technology to go beyond 64GB. The more, the merrier!

 

[UaVaj]

unless you are pulling repetitive data off the drive. that cache is moot.

as for raid. you will see big improvement in performance at the expense of a some reliability.

if you already have both drive. go for it.
if you have to start from scratch. get a ssd for os/program and leave the hd for storage/data.

 

[Cerb]

unless you are pulling repetitive data off the drive. that cache is moot.

That happens to be quite common, and it frees up IO from the HDD, in the process. SRT also performs write caching, but how helpful that is in enhanced mode is quite debatable, since maximized mode is needed for write-back (in enhanced mode, a new write going to the cache also goes to the HDD, and if the HDD gets bottlenecked with writes, the SSD will be sitting there waiting for it to finish). If you can't reasonably or affordably fit your storage onto SSDs, it's a very good option to use. I very much agree they aught to allow it to be any arbitrary size, though, with HDDs getting ever-bigger.

 

[Blue_Max]

I'm seriously considering the SRT route... getting the fastest 64-120GB SSD out there and pairing it with a decent 7200RPM drive should net decent results, right? Probably better than the lousy 8GB found on these SSHD's!

 

[Cerb]

I'm seriously considering the SRT route... getting the fastest 64-120GB SSD out there and pairing it with a decent 7200RPM drive should net decent results, right? Probably better than the lousy 8GB found on these SSHD's!

No probably about it. Hybrid drives are mostly about speeding up boot and a few programs starting, while SRT gives you that and a general-purpose read and write cache. Outside of notebooks, a bigger SSD for an OS drive, and getting bigger HDDs to store more stuff, are generally better values, but SRT does work, and works well, IME, if you must try to pep up a HDD, instead of moving access-time-sensitive data explicitly to an SSD.

 

[Blue_Max]

Appreciate the tips, Cerb.