Is the workload random or sequential? To write a ful stride, we need to write to all data disks. Any questions, feel free to ask. That means you need at least 4 arrays per V to get maximal CPU core performance. Type in a Name: Previous Entry Main Next Entry.
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In this case, 8 data disks, so 8x kb 2MB.
Do you need the most MB or GB per second? Is the workload random or sequential? Part 1 – Summary.
When a RAID-5 array has to write to a strip, it needs to sdd the existing strip, read the existing parity strip, update the existing strip read modify, write and then calculate the new parity. Within the SVC softare that runs on the V, we have worked for many years over 12 now on making the code path and per core processing as consistent as possible.
Avc a reason for quarantining this blog entry optional: Here your reads will come from just one disk in the array. Find the duplicate idea: You lose the parity disk’s worth of capacity with parity data. Any questions, feel free to ask.
Troubleshooting VSS and SAN Volume Controller, Storwize V7000, or DS8000
Looking at IBM Spect Sgc in a Name: Now we only have to use 9x kb writes, and no reads. What striping is happening where?
An array has a defined strip size. With V, always configure at least 4 arrays, and if possible, multiples of 4. Previous Entry Main Next Entry.
IBM Subsystem Device Driver for AIX – United States
Since arrays can be accessed through both nodes in the V system, 4 is enough, on each node, one array will be assigned and processed through one core.
There are so many factors that contribute to getting the best performance out of a storage system, that it really does depend on what you are trying to achieve. This is commonly referred to as “full stride writes” or “full strip writes” – essentially you are writing all new data across all disk that make up the array, and in memory, calculating the new parity data.
Lets say the strip is kb. Optimal configurations require at least 4 arrays, to ensure maximal core usage.
That means you need at least 4 arrays per V to get maximal CPU core performance. To write a ful stride, we need to write to all data disks.
Sequential Processing When it comes to sequential reads and writes, here you can get the benefits lbm both capacity and bandwidth.
IBM Subsystem Device Driver Device Specific Module (SDDDSM) – United States
How to find the IBM If the host then issues a single 2MB write, we can write across all 8 strips, in memory calculate sdr parity and write that too. In Part 3, I will discuss storage pool configurations, mdisk groups in old SVC parlance And finally in Part 4, I will discuss volume vdisk and host configurations.
Is the host optimally configured for the storage system? I was once creditied in an IBM Redbook, with the comment: Thats because when it comes to all things related to storage performance, more often than not, “it depends”.