|reply to Octavean |
Re: TRIM / "garbage collection" with RAID0
Well thanks for your most informative links and replies Octavean.
Looks like I have opened a can of worms here regarding RAID0 and TRIM.
At the time of my RAID creation and Windows installation, I was led to believe RAID0 and TRIM together was possible, and had NO inherent problems!
Can you further enlighten me with what kind of "issues" I can expect to encounter with my present Win7 installation on to (2) 64GB Crucial M4 SSDs in a RAID0 array?
New York, NY
Unfortunately I am not entirely sure what you might encounter over time.
I have a number of different SSD models of which a Crucial M4 256GB SSD is one of them. However, I dont currently have an SSD RAID 0 array setup. Although I have run such configurations in the past and have had no real problems or major concerns over performance loss:
»SSD Raid 0 Array 4x60GB Setup Test Run
Author: Allyn Malventano
Date: February 17, 2010
I don't have and pretty charts or graphs to explain this next part, but I will share an observation I made during my fragmentation testing. When running my fragmentation tool, I observe IOPS drop as the drive becomes more and more overloaded with the task of tracking the random writes taking place. Here the JMicron controller behaved like all other drives, but where it differed is what happened after the test was stopped. While most other drives will stick at the lower IOPS value until either sequentially written, TRIMmed, or Secure Erased, the JMicron controller would take the soonest available idle time to quickly and aggressively perform internal garbage collection. I could stop my tool, give the drive a minute or so to catch its breath. Upon restarting the tool, this drive would start right back up at it's pre-fragmented IOPS value.
Because of this super-fast IOPS restoring action, and along with the negligible drop in sequential transfer speeds from a 'clean' to 'dirty' drive, it was impossible to evaluate if this drive properly implemented ATA TRIM. Don't take this as a bad thing, as any drive that can bring itself back to full speed without TRIM is fine by me, even if that 'full speed performance' is not the greatest.
This type of self-healing (i.e. without needing TRIM) is great for those wanting to run a few SSD's behind a RAID, since no RAID implementation is currently capable of passing TRIM from the OS to the arrayed SSD's. Better yet, considering this drive is tailored to the budget crowd who may very well still be running XP or Vista, it's good to have a few choices that don't require TRIM to maintain decent levels or performance.
This was applicable for the SSD model that I was chiefly using in the RAID 0 array which was the Kingston SSDNow V Series SNV-S2 64GB (3x but not applicable to the single 60GB OCZ Agility in the array).
Personally I would just keep an eye on performance overall. That does not mean benchmark the configuration aggressively. It just means take note via empirical observation of your system in everyday use and maybe one or two benchmarks a month (or every other month) to look for a delta. Some SSD models (controllers) may degrade performance somewhat as the storage is fills up (independent of TRIM and Garbage Collection concerns) so keep that into consideration as you record your data.
As SSD prices fall you may find that you can replace your 2x64GB RAID 0 array relatively cheaply. I replaced my 4x60GB RAID 0 configuration with a single 240GB SSD that was about the price of one of the single 60GB / 64GB SSD models when they were new.
Ive personally been thinking about replacing my Asus P8P67 Pro with a Gigabyte GA-Z77X-UP5 TH (dual Thunderbolt) for ~$239.99 or a GA-Z77X-UP4 TH (dual Thunderbolt) $184.99.