NetApp vFilers follow this idea. As I was rebuilding my homelab I thought I would try to see what changing RAID levels would do on these homelab / s(m)b devices. For deduce (NetApp) the overhead is zero. To be clear, when you look at the sizing guides and internal tools we use to generate customer configs within EMC, we actually assume a pretty negative scenario (a conservative approach along what Duncan was pointing out initially). Now, ONTAP 8, and the integration of Spinnaker represents the first big architectural change in a while - and I'm personally and professionally interested and am watching closely - it's important to have strong competitors in our (or any) industry. HDS - the first to really embrace the idea of placing a array in front of an array for heterogenous storage virtualization. If you want to know something they can be used for now, one trick is to map them to USB drives. If you insert and remove a USB drive frequently, but want it to keep If you don't have enough backing spindles to handle the steady state write IO workload, eventually (and eventually is a short time - enough time for the array write cache to fill) the write performance becomes largely gated by those backend disks. Random write IO = blink.. I would like to clear off/erase all of the programs on my hard drive and clean it up before I donate my computer to a worthy cause. What's the best/simplest way to Like I said - cache is good, and more is generally better. Like I said it's an average of theoretical numbers. Get someone write my paper 3d glasses The application of dedupe to effectively raise the amount of cache - I wouldn't say a bad thing about it - good for NetApp innovation in that area. Wow, thanks for the comments everyone. There is no write impact as the process is a background process (similar to NetApp Dedupe in that regard, though the Celerra dedupe/compress runs all the time, doing work when there is free CPU cycles, and idle when not). My understanding is that compression (EMC) requires a block range of the file to be copied, uncompressed, and then accessed.. It is one of those technologies though that does make you potentially change what type and how many spindles you need.
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Following Chad & Keith's lead here.. Just something I wanted to document for myself as it is info I need on a regular basis and always have trouble finding it or at least finding the correct bits and pieces. You got it right, there is a balance and deduplication only changes how you size storage. But basically you're right about IOPS. First intelligent caching (deduce aware cache) is available in every array powered by ONTAP, so you get the benefit without PAM (PAM increases the amount of cache to insane levels). If one's can't get these features form their array then they soul virtualize their existing arrays with a NetApp vSeries (it's the same as virtualizing a server with ESX/ESXi - allows you do more with less). We know this is probably our largest data set in our VMware environment, and consists of multiple VMs each with low to moderate IO needs. In my world with NetApp Deduplication and the dedupe rates seen with most virtual environments customers on the slower drives can run out of IOPS long before they use up all the available capacity. FYI (and important for technical accuracy) - Celerra NAS does both a deduplication (for indentical files) and compress (within and across files). Let's say you have a large write cache - 100GB in size. XOR and blasts it down. Especially by the sales team. In my mind, the disparity of performance (10x) between read and write nullifies the validity of the averaging method for SSD's, and could lead to some really bad results in random-write oriented applications (i.e. The 1000 IOps this VM produces actually results in 2800 IO's on the backend of the array, this makes you think doesn't it? Thanks Duncan - a great topic to bring to a broader audience! As with most things, all engineering decisions tend to have trade-offs. RAID-6 vs RAID-DP is akin to the difference between RAID-5 and RAID-4. The same effect occurs if you are using VMware View composer (the base replica which serves all the images fits in a smaller effective cache, but has the impact as if all the linked clones are cached. SSD). This makes understanding SSD performance a bit more important. In the comments there's link to a ZDNet article which I used as one of the sources. Companies! If you look at a NetApp device sitting beside any other array, and look at the disk LED pattern, this behavior is visible to a human eye. They are both data reduction techniques. What is your block size 8k 16k 32k 64k etc. On the Mini SD adapter, there is a lock tap you push down usually when you put your mini SD card in to it, then into the USB adapter. To turn off the write protection
I have two IX4-200Ds at home which are capable of doing RAID-0, RAID-10 and RAID-5. Toondoo lets you create comic strips and cartoons easily with just a few clicks, drags and drops. Get started now! When it is finished and I can find the time I will try to do a performance test based on different raid-levels. Celerra dedupe has been mainstream for about a year now, with most customers seeing about a 40-50% savings on general purpose NAS (filesystem) use cases. On varying datasets, they have varying capacity savings efficiencies. Don't take my word for it just ask VMware engineering. Could one use RAID 5, sure, but let's agree that in doing so one needs to address the mathematical reality that eventually they will lose data (this is not my opinion - view the stats on any disk drive and do the math). Background scans, disk scrubbing, RAID rebuilds all increase subsystem load. But, to think that NetApp has an exclusive hold on being different - man, that's a bit of hubris. Comeback! How to Insert a Disc into insert the disc depends on how your drive eats the tray type of CD-ROM/DVD drive, but don't insert them into the slide
In my mind, the most important factor to understand in contemplating array sizing for performance is how read/write caching will influence the usable IO of a storage pool (group of disks). RAID 6, 10, and DP have varying RAID overhead in terms of IOPs (where RAID 10 and DP stand out), but also in terms of RAID capacity overhead (where RAID 6 and DP are very efficient and practical). Conversely if you look at the same on a CLARiiON (or other arrays more generally), you'll see the lights all doing this = blink, blink, blink all in a crazy pattern (the IO's are getting laid out all in their localized places). Second, advanced higher end arrays do a LOT of write coalescing - batching up the IOs, and trying to maximize full stripe I/O and other factors. http://eclecticanchormaker.tumblr.com/post/144927544491/i-will-pay-someone-to-do-my-assignment This approach actually helps in looking at raid device queue sizing in ZFS-based pools as a limiting factor where large numbers of disks are used to back relatively few presented LUNs (ZFS evil tuning guide). " Please insert an empty disc to write to" no In my situation, I would insert an empty disk and a Nero thinks the disk you place in the drive has Not to take away from RAID-DP, but it doesn't get write performance for free: it does lose something to RAID5/6 in terms of read IOPS where small(er) numbers of disks are used. EMC - unique introduction of CAS, still unique with COS, MPFS, and of course the leading the way with use of SSDs.
Solid state disks can be what Keith states (and Duncan, consider adding them to your table - they do 6000-8000 random IOps) - a small number of IOps eating spindles behind an even faster read/write cache - and even host-based use of flash, like VMware's recent SSD as vswap study, or FusionIO cards in servers. How to Insert a Disc into Another type of disk drive works like These discs work fine in the tray type of CD-ROM/DVD drive, but don't insert them into the When we see a good idea done somewhere else, you can count on us trying to see how we could provide similar or adjacent value to our customers in a way that can be done in our technologies. 234 thoughts on Fixed: USB drive unusable, unformattable, it shows please insert a disk into drive byte usb drive but my pen drive is not working What are your writes, sequential or random. I hope I can do the same tests on one of the arrays or preferably both (EMC NS20 or NetApp FAS2050) we have in our lab in Frimley! I personally wonder if that hubris is why NetApp doesn't do SSDs as an option along with PAM - perhaps it's inconceivable there (thinking of that dude in Princess Bride who ran around saying inconceivable!) that good ideas might come from elsewhere. Benefits of. If one uses traditional storage arrays one has to make a lot of choices around a number of technologies as no single RAID technology meets the goals of providing high availability, high utilization of the physical resource, and performance especially when serving a dense data set (by dense I am referring to deduce, compression, thin provisioning, linked clones, etc). To answer the question posed by Scott above, RAID-DP's write performance penalty is much less than standard RAID-6 because in RAID-DP, the dual parity bits are not striped accross all drives in the raid set. That said, I like to track my performance estimates of sequential (read bias), random (write bias) and average IOP (designed mix) estimates to determine how close to the mark we get in the final system. Anyway, Chad is correct. Thanks for posting this article it has sparked great discussion.
The technology a storage array provides need to be very non-traditional and our customers believe that the combination of RAID-DP, deduce, intelligent caching (both in the array and with PAM) meet all of these goals with a reduced footprint. That's the penalty which is introduced when selecting a specific RAID type. Caches also help with absorbing write bursts, but the backend storage (spindles) need to be able to destage (commit) the write cache otherwise it overflows, and then the host sees the performance of the backend (non-cached disk) directly. Maybe a practical way to discuss storage IO is in a broader sense at an architectural level where we can begin by looking at a specific data type. Read was consistent at 111MB for every single RAID level. Subscribe Now! Core. What are the differences between NT Workstation and NT Server? What does NT stand for? What is the NT Boot Process? When I boot up NT, it pauses for about This is where alternative approaches and/or write coalescing become increasing important, because re-characterizing random IO as sequential IO can get these raid sets back to scaling with disk count. Sometimes file-level dedupe is extremely space/compute efficient (in the case of general purpose filesystems for example), sometimes it is not. As the vendors have changed and improved their technology we constantly have to adapt those definitions.
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