Dataset · Correlated failures · OSDI 2010

Google measured a disk MTTF of 10 to 50 years but a node MTTF of 4.3 months; 37% of node failures came in bursts

Ford et al., OSDI 2010, studied tens of Google storage cells over one year. Node MTTF was 4.3 months against 10 to 50 years for a disk, and 37% of failures were part of a burst of at least 2 nodes. Cross-check rows come from NetApp (FAST 2020) and HPC1 (FAST 2007) and show clustered drive replacements.

Download CSV14 rows · 7 columns · CSV

File /data/datasets/storage-availability-correlated-failures.csv · JSON metadata · All datasets · Human-readable note on hesela.com

Method

The CSV transcribes figures printed in Ford et al. (OSDI 2010) and cross-check rows from Maneas et al. (FAST 2020) and Schroeder and Gibson (FAST 2007). It does not read chart values.

Limits

One operator's cells and software; figures describe nodes and racks as well as disks.
Disk MTTF is a printed range of 10 to 50 years, not a vendor rating.
The 10% sensitivity results come from the authors' model with 3-way replication.
The 37% burst share depends on a 120 second window.
The cross-check rows are other fleets with other definitions.

Table

14 rows, the same rows as the CSV. Value low and value high are the printed range ends, or a single printed value in the high column. Units are in the unit column. Sources are the pages opened on 2026-10-10.
Measure	Value low	Value high	Unit	Scope	Note	Citation
Storage nodes per cell studied	1000	7000	nodes per cell	Tens of Google storage cells, one year	Printed as 1000 to 7000 nodes in each cell.	ford-osdi10-pdf
Node unavailability events lasting longer than 15 minutes	not stated	10	percent of events	Same cells	Printed as less than 10%; the paper then studies only events of 15 minutes or longer.	ford-osdi10-pdf
Disk mean time to failure	10	50	years	Google cells; counts software and hardware causes	Table 2 range; disk failures are permanent.	ford-osdi10-pdf
Node mean time to failure	not stated	4.3	months	Same cells	Table 2; most node failures are transient.	ford-osdi10-pdf
Rack mean time to failure	not stated	10.2	years	Same cells	Table 2.	ford-osdi10-pdf
Failures that are part of a burst of at least 2 nodes	not stated	37	percent of failures	Bursts defined with a 120 second window	Printed as 37%; the authors estimate that close to 37% are truly correlated.	ford-osdi10-pdf
Random failures wrongly merged into a burst	not stated	8.0	percent of non-correlated failures	Same window; 0.068% for a burst of at least 10 nodes	Upper estimate of mis-clustering.	ford-osdi10-pdf
Older data blocks that fail a checksum on scrubbing	0.0000001	0.000001	fraction of older blocks	GFS background scrubbing	Printed as 1 in 10^6 to 10^7; concentrated on a small number of disks.	ford-osdi10-pdf
Gain in stripe availability from a 10% cut in the disk failure rate	not stated	1.5	percent (upper bound)	Model with R = 3 replication	Printed as less than 1.5%.	ford-osdi10-pdf
Gain in data availability from a 10% cut in the node failure rate	not stated	18	percent	Same model	More than 12 times the disk figure.	ford-osdi10-pdf
Chance of a drive replacement in a random week	not stated	0.0504	percent	NetApp RAID groups, about 1.4 million SSDs	Baseline for the next row.	maneas-fast20-pdf
Chance of a replacement within a week of a previous one in the same RAID group	not stated	9.39	percent	Same fleet	More than 180 times the baseline; 52% of consecutive replacements fall within a week.	maneas-fast20-pdf
Correlation of disk replacements in consecutive weeks	not stated	0.72	correlation coefficient	HPC1 system, whole lifetime	0.79 for consecutive months; 0.4 to 0.8 when one year is used.	schroeder-fast07-pdf
Spread in expected weekly replacements after a quiet versus a busy week	not stated	9	times	HPC1 system	Printed as a factor of 9 between the first and third bucket.	schroeder-fast07-pdf

Columns

measure (string): The quantity as the source names it.
value_low (number): Lower end of a printed range. Empty when the source prints a single value.
value_high (number): Single printed value, or the upper end of a range. For 'less than' it is the stated bound.
unit (string): Unit of the value columns: nodes per cell, percent, years, months, fraction, times, or correlation coefficient.
scope (string): Population and window the value applies to.
note (string): What the value is not, or the source wording behind it.
citation_id (string): Id of the opened source in the citations list.

License

Small derived table of figures printed in Ford et al. (OSDI 2010), Maneas et al. (FAST 2020), and Schroeder and Gibson (FAST 2007), with credit. Not a Creative Commons license. The USENIX papers remain with their authors or publishers. This file is not a copy of the papers and not the data.