Comments on: RAID vs SSD vs FusionIO

By: DangerD

DangerD — Wed, 28 Oct 2009 14:08:56 +0000

Seems like some folks are on to this SSD optimisation already.

http://rethinkdb.com

By: Pounce

Pounce — Thu, 02 Jul 2009 00:08:11 +0000

Ben, I think you meant $5.90 per GB, not 5.9¢ per GB.

By: james braselton

james braselton — Thu, 21 May 2009 17:32:19 +0000

HI THERE CLICK FREE HAS A NEW CLICK FREE TRAVLER THAT IS A SSD BACK UP 16 32 OR 664 GB

By: SSD Kevin

SSD Kevin — Fri, 15 May 2009 00:04:30 +0000

From my first hand experience with the iodrive; they are not ready for prime time. The cards are fast… but have a substantial chance for metadata corruption, as well as the worries of card failure (see post from Vadim). There is so much redundancy in a SAN, it is tough to overlook as you put valuable data on these cards. I am going to hold on and leave these in the lab until the SSD market matures.

By: Carl Johnstone

Carl Johnstone — Mon, 11 May 2009 16:03:08 +0000

How do SATA disks compare? I realise they’re going to have a lower performance – but that comes at a much lower price than SAS disks…

By: Ben

Ben — Tue, 05 May 2009 15:15:12 +0000

Small note: Your RAID 10 assumes you pay only for the drives — not the RAID controller. So it may be more realistic to add about $200. Therefore:

8 x $190 = $1520 for disks + $200 for controller = $1790
$1720 / 292GB useful space = 5.9¢ per GB

Still cheap in comparison.

By: Didier Spezia

Didier Spezia — Mon, 04 May 2009 10:18:00 +0000

Very interesting benchmark. On a Schooner presentation (http://www.percona.com/ppc2009/PPC2009_Schooner_Percona_Presentation.pdf), it is stated (slide 12), that PCIe flash cards (a la FusionIO) “use lots of server processor cycles and memory for garbage collection, write coalescing, wear leveling, mapping”. So in other words, using SSD drives with a good RAID controller is supposed to lead to a more balanced machine. I’m just curious: did you really measure such effects or is is just marketing fluff? For instance, is the extra CPU consumed with FusionIO can be correlated with the extra TPM you get?

By: Kevin Burton

Kevin Burton — Mon, 04 May 2009 07:33:24 +0000

To be honest these benchmarks are somewhat pointless.

Who would run a database without durability?

It’s better to run innodb flush tx at log commit=2 rather than have the disk subsystem do this.

You can lose some transactions but at least when you restart you don’t have data corruption.

By: Mark Callaghan

Mark Callaghan — Sun, 03 May 2009 22:56:28 +0000

Doesn’t XtraDB have an option to disable flushing of all dirty pages in an extent when one of them has an LSN that is too old? If so, when will we get performance results from Vadim on SSD to determine whether that is useful? It will reduce the overall write rate.

By: Baron Schwartz

Baron Schwartz — Sat, 02 May 2009 17:33:26 +0000

Pat, I’m the least expert of anyone commenting here, but it’s my opinion that a database truly designed for SSD simply doesn’t exist.

Also realize that SSD is a Flash device with a hard-drive-emulation in front of it (loosely speaking). In my opinion, the future will be more like “I’ve got a vast pool of memory” than “I’ve got memory and hard drive” or “memory plus SSD.” SSD might only be an interim technology as we edge towards something really different. A lot of things need to be questioned. What do we need filesystems for? What is I/O and what is memory access, and why do we differentiate the two?

It’s not just databases — operating systems probably aren’t ready, either. But this is status quo: software historically lags hardware, by and large.

Back to my Perl coding.