FAS and V-Series Storage Systems Discussions

Re: Defeating NetApp "Right Sizing" for more Usable Capacity

And of course you still expect NetApp to exchange your failed drives within 4 hours....?

Serious: from an engineering point of view it is very fascinating what you can do (reminds me of those guys who are trying to break into Playstation or Wii etc) - but what's the benefit in real world? Neither do most customers (or even partner) have the knowledge, will or time to do such tricks nor will they take the loss of guarantee into account.

And you did it in a cheesy low-budget 2020 to save yet some other bucks....

Nonetheless I agree with you, and I am still missing some exprehensive explanations from NetApp, why we have to loose so much space. Especially when disk pricing is not far away from robbery...


Re: Defeating NetApp "Right Sizing" for more Usable Capacity

I thought these drives were downsized out of disk factory, not by NTAP and that its the same across all storage vendors, is that not the case?

A bit like as an end user in a shop I ve NEVER been able to get the disk size I was sold. Every disk I ever bought was down sized no matter what.

I dont see this as a NTAP specific issue, rather an industry standard.

I assume you are out of warranty? Well done on getting it to work though.


Re: Defeating NetApp "Right Sizing" for more Usable Capacity

Correction: FC and SAS disks have 520B blocksize with 512B for data and 8B for chechsum, so checksum is integrated into the block. SATA in contrast doesn't.

FC and SAS drives use 520-byte sectors. FC and SAS drives are formatted using the block checksum scheme (BCS) method. Each 4KB WAFL® (Write Anywhere File Layout) block is made up of eight sectors. The last eight bytes of each sector are reserved to store the block checksum. This means that each 520-byte sector is effectively 512 bytes of usable capacity. In doing the math, you end up with 512 bytes x 8 = 4,096 bytes, or a 4kB WAFL block.
SATA drives start with 512-byte sectors. In order to store block checksum information, Data ONTAP uses the BCS 8/9 checksum method when formatting the drive. This means that each 4kB WAFL block is made up of nine sectors, eight that are used to store data and the ninth sector used to store the checksum (8/9).

See: http://www.netapp.com/us/media/tr-3838.pdf

Re: Defeating NetApp "Right Sizing" for more Usable Capacity

@radek_kubka wrote:



"1) Disk manufacturers actually do lie - to them 1GB equals (as per Seagate datasheet) "one billion bytes", whilst if you do proper base 2 arithmetics (1024*1024*1024) 1GB in fact is 1,073,741,824 bytes. So at the very beginning your drive marketed as 1TB is in fact ~931GB."


Well that is not a lie, the "G" in GB is the giga prefix from the SI units and means 1,000,000,000 (https://en.wikipedia.org/wiki/International_System_of_Units) Why any computer guy thought it would be a good idea to use incorrect prefixes only the gods will know. They should have used/invented the binary prefix instead: https://en.wikipedia.org/wiki/Binary_prefix


Re: Defeating NetApp "Right Sizing" for more Usable Capacity

FYI, with Data ONTAP 8.1.1 NetApp introduced a new “Advanced Zone Checksum” style (“AZCS”) for native 4KB formatted HDDs and for V-Series LUNs. From a capacity perspective it has a cost of of 1 – 63/64 or 1.56% of the HDD capacity vs. the previous BCS checksum style emulation on 512bps drives that was 1 – 8/9 = 11.1% of the HDD capacity. The 4KB native disks are of type MSATA found in the DS4486 shelf in 3TB and 4TB capacities and are shipping today.


I try to always distinguish between binary and decimal using the ANSI standards to avoid confusion.   i.e. 1GB=1,000,000,000 bytes;  1 GiB=1,073,741,824 BYTES.