What is RAID block size?
The default RAID Group stripe block size is 64KB. For RAID 5 (4+1) the stripe size will be 256KB (4*64). If the majority of aligned block size in not 256KB, it would result in striping to the next drive. This is less optimal for high bandwidth, large block random IO.
What is the best chunk size for RAID 0?
What you don’t want is a single I/O getting sent to two disks, since waiting for the heads will slow things down. So you want a large chunk size – at least 64 KB or more.
What is RAID size?
A RAID 0 setup can be created with disks of differing sizes, but the storage space added to the array by each disk is limited to the size of the smallest disk. For example, if a 120 GB disk is striped together with a 320 GB disk, the size of the array will be 120 GB × 2 = 240 GB.
What is the best raid for SSD?
RAID 0
SSDs are not widely available in the same range of sizes. RAID 0 is the best way to go, since there is no redundancy and all available storage is used on every drive. You also get a nice speed boost that may be helpful if you are working with extra-large file sizes.
What is RAID chunk size?
The RAID chunk size should suit the I/O characteristics of the data you’re working with. For this use case smaller RAID chunk sizes (for example, 512 bytes — one block — to 8 KB) fit the bill because you want to take data from one drive while the others seek the next chunks to be read.
How much disk space do you lose with RAID 5?
RAID 5 results in the loss of storage capacity equivalent to the capacity of one hard drive from the volume. For example, three 500GB hard drives added together comprise 1500GB (or roughly about 1.5 terabytes) of storage.
How big is a stripe in a RAID controller?
A RAID controller can have a stripe size for an array using striping (e.g. RAID-5 or RAID-10). If the array has (for exmaple) a 128k stripe, each disk has 128k of contiguous data, and then the next set of data is on the next disk.
How big are the blocks on a disk?
Or does nothing get batched together, and therefore I loose disk space with every mismatch between defined block sizes? A disk has a fixed sector size, normally 512 bytes or 4096 bytes on some modern disks; these disks will also have a mode where they emulate 512 byte sectors.
Why is there a limit to the size of a block?
Misalignment of partitions and file system blocks to RAID stripes can cause a single filesystem block read to generate multiple disk accesses where only one would be necessary if the file system blocks aligned correctly with the RAID stripes. The database will allocate space in a table or index in some given block size.
Can a file system allocate blocks of storage?
Some (e.g. Windows 2003 server) will not, and you have to use a partition utility that does support stripe alignment to ensure they do. The file system will allocate blocks of storage in chunks of a certain size. Generally this is configurable – for example NTFS will support allocation units from (IIRC) 4K to 64K.