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11

I know this is probably a hypothetical question... But the IT world really doesn't work that way. There are realistic constraints to consider, plus other things that can influence IOPS... 50GB and 100GB disks don't really exist anymore. Think more: 72, 146, 300, 450, 600, 900, 1200GB in enterprise disks and 500, 1000, 2000, 3000, 4000, 6000GB in ...


10

The key to the answer to your question is read-ahead. Once upon a time, I also happened to have that issue. IOW, for optimal sequential read performance all disks should be permanently involved into Input. When you use dd w/o directio (see man dd), write operation is not being performed immediately, but goes through OS cache, so it has more chances to ...


8

poige is exactly right about the write cache, but here are more details. dd with zeros and using write cache is not the right way to benchmark (unless you want to test the write cache of course, which is probably only useful for a file system, to see how much it syncs metadata, creates new files, etc.) (and likely dd is always the wrong type of benchmark, ...


7

To answer your question directly - all other things being equal = no change whatsoever when GB changes. You don't measure IOPS with GB. You use the seek time and the latency. I could re-write it all here but these examples below do all that already and I would simply be repeating it: http://www.ryanfrantz.com/posts/calculating-disk-iops/ ...


7

One place where there is a direct relationship between disk size and IOPS is in the Amazon AWS Cloud and other "cloudy services". Two types of AWS services (Elastic Block Store and Relational Database Service ) provide higher IOPS for larger disk sizes. Note that this is an artificial restriction placed by Amazon on their services. There is no ...


4

I think, it was just an I/O timeout. I had such issues with Linux VMs on remote NFS datastore. NFS was just too slow, and some of our Linux VMs switched their disks into read-only mode (and therefore stopped responding). Probably, during resize your NFS datastore was overloaded and this caused issues. Do Linux VMs work fine after reboot? To avoid such ...


4

I should point out that IOPS are not a great measurement of speed on sequential writes, but lets just go with it. I suspect the seek and write times of disk heads is pretty consistent despite the size of the disks. 20 years ago we we're all using 60GB disks with (roughly - certainly not linearly) the same read/write speeds. I am making an educated guess ...


4

First off - check vendor recommendations. Some vendors are more scrupulous than others, but they'll generally have a list of 'known compatible' cards. If you lack this information - as you seem to - I would start with buying Emulex or QLogic HBAs, and avoid anything else unless you have a specific entry in an interoperability matrix. You will probably ...


3

The performance added to the storage scales with each spindle added. The rotational speed of the drive is the biggest factor, so adding a 10k RPM drive will give more performance (in terms of IO/s in random IO or MB/s in streaming IO) than a 7.2k RPM drive. The size of the drive has virtually no effect. People say small drives go faster simply because you ...


3

You'll want to look into implementing some of the SES commands. SES stands for SCSI Enclosure Services, and is the protocol used by external JBOD storage enclosures to report health and do things like illuminate disk LEDs. Nexenta has sesctl, but there are other third-party options like SmartMon-UX. Are you actually using real Solaris, or a ZFS-based ...


3

Storage performance isn't always about throughput... So to reality... Today, I would likely build a NAS solution for the client set you have with dual bonded 10GbE connections to a pair of cross-stacked switches (or a chassis switch). It's not like you have that many options... NAS --- 2 x 10GbE ---> switch --- 1GbE ---> computing workstations ...


2

I bought 6 of the 1.2tb cards in the last couple months. One of them has already failed. So I would absolutely raid them. I used windows active disk mirror. The drive failed with the message "missing LEB map". I was told it would need to be swapped out. But to get the RMA approved I would need to take pictures on both sides of the failed card (requiring a ...


2

That's actually an LSI Engenio Class 4600 (0834) which was bought by NetApp in 2011 and is no longer available - I was struggling to find documentation either to be honest. I know some are huge fans of Q-Logic FC HBAs but I'm personally a fan of Emulex ones and although I can't find any form of interoperability matrix for this product I think that if you ...


1

It looks like what I want is to have dedicated journal disks. They will effectively act as a write cache, at least as far as my application is concerned. This can be accomplished by adding one or more disks (preferably SSDs) as dedicated journal disks: Add-PhysicalDisk -StoragePoolFriendlyName "<your storage pool name>" -PhysicalDisks <physical ...


1

If you assume all else is equal, performance characteristics of disks of larger capacity don't change very much. An 10K RPM FC drive has very similar characteristics regardless of whether it's 300GB or 3TB. The platters rotate at the same rate, and the heads seek at the same speed. Sustained throughput likewise - not much difference. This is the root of a ...


1

As far as I know ESXi doesn't make use of TRIM commands from a VM. I havn't found anything definite or official from VMware but in a comment to a blog post I found this: In VMs TRIM is definetely not available, I already checked that. FAQ: Using SSDs with ESXi So it looks like mounting filesystems with the discard option won't help you.


1

If this is a NetApp (or any other NFS server), be sure that the NFS best-practices for the ESXi host configurations are in place. For NFS deployments, I always make some adjustments to NFS heartbeat and timeout settings. That may apply in your case. Check with your storage engineer to see what the specific recommendations for your unit are.


1

You need to some data collection. This can take basically take 4 forms that I can think of. A combination of them might be best, but individually I'm listing them from what I consider to be worst to best. Ask the vendor (or a set of vendors) and base it on what they tell you. They should all have calculators for guessing this sort of load. They might even ...


1

Well... could be a number of things but generally speaking disk rescans causing lockups is often a side of a bad hard drive. You could try removing each disk in turn and rescanning to see if it only fails when a specific disk is inserted. If these are new disks or you've already run a diag on them and think they are fine then then I'd start checking for ...


1

You should really be talking with your IBM partner on cases like these, as they're the best ones to answer these kind of questions. That being said - the storwize v7000 is a dual-controller system. As long as you have dual paths (you mentioned DM multipathing) to each controller then a storage processor upgrade should reboot one controller at the time, ...



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