Hi William,
My comment was just a heads up so other developer’s don’t get take a hit like I
did. Just look at your disk SMART data and you will be surprised by the number
of errors on those disks. Here is an example of SMART info from one of my 4TB
WD disks I use with TimeMachine. As you can see, 0 errors in the log. On my
development system, I use 1TB Seagate SSD drives and they work great.
Last Checked : November 29, 2015 2:25:14 PM PST
Last Checked (ISO 8601 format) : 2015-11-29T14:25:14
Advanced SMART Status : OK
Overall Health Rating : GOOD 89.9%
Overall Performance Rating : GOOD 89.9%
Issues found : 0
Serial Number : WD-WCC4E0HHFLY1
WWN Id : 5 0014ee 260fbf0bd
Volumes : TimeMachine1
Device Path : /dev/disk4
Total Capacity : 4.0 TB (4,000,787,030,016 Bytes)
Model Family : Western Digital Red
Model : WDC WD40EFRX-68WT0N0
Firmware Version : 82.00A82
Drive Type : HDD 5400 rpm
Power On Time : 5,078 hours (7 months 1 days 14 hours)
Power Cycles Count : 54
Current Power Cycle Time : 22.1 hours
=== DEVICE CAPABILITIES ===
S.M.A.R.T. support enabled : yes
DriveDx Active Diagnostic Config : Base config [hdd.default]
Sector Logical Size : 512
Sector Physical Size : 4096
Physical Interconnect : SATA
Removable : no
Ejectable : no
ATA Version : ACS-2 (minor revision not indicated)
SATA Version : SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Bay # : 1
I/O Path :
IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/PEG1@1,1/IOPP/UPSB@0/IOPP/DSB2@4/IOPP/UPS0@0/IOPP/pci-bridge@3/IOPP/pci1b21,612@0/AppleAHCI/PRT0@0/IOAHCIDevice@0/AppleAHCIDiskDriver/IOAHCIBlockStorageDevice
Attributes Data Structure Revision : 16
SMART Command Transport (SCT) flags : 0x703d
SCT Status supported : yes
SCT Feature Control supported : yes
SCT Data Table supported : yes
Error logging capabilities : 0x1
Self-tests supported : yes
Offline Data Collection capabilities : 0x7b
Offline Data Collection status : 0x0
Auto Offline Data Collection flags : 0x0
[Known device ]: yes
[Drive State Flags ]: 0x0
=== CURRENT POWER CYCLE STATISTICS ===
Data Read : 2.2 GB
Data Written : 3.5 GB
Data Read/Write Ratio : 0.62
Average Throughput (Read) : 1.2 MB/s
Average Throughput (Write) : 932.4 KB/s
Operations (Read) : 175,372
Operations (Write) : 153,554
Operations Read/Write Ratio : 1
Throughput per operation (Read) : 12.9 KB/Op
Throughput per operation (Write) : 23.6 KB/Op
Latency Time (Read) : 0 ns
Latency Time (Write) : 0 ns
Retries (Read) : 0
Retries (Write) : 0
Errors (Read) : 0
Errors (Write) : 0
=== PROBLEMS SUMMARY ===
Failed Indicators (life-span / pre-fail) : 0 (0 / 0)
Failing Indicators (life-span / pre-fail) : 0 (0 / 0)
Warnings (life-span / pre-fail) : 0 (0 / 0)
Recently failed Self-tests (Short / Full) : 0 (0 / 0)
I/O Errors Count : 0 (0 / 0)
Time in Under temperature : 0 minutes
Time in Over temperature : 0 minutes
=== IMPORTANT HEALTH INDICATORS ===
ID NAME RAW VALUE
STATUS
5 Reallocated Sector Count 0
100% OK
197 Current Pending Sectors Count 0
100% OK
198 Offline Uncorrectable Sector Count 0
100% OK
199 UDMA CRC Error Count 0
100% OK
=== TEMPERATURE INFORMATION (CELSIUS) ===
Current Temperature : 33
Power Cycle Min Temperature : 27
Power Cycle Max Temperature : 37
Lifetime Min Temperature : 23
Lifetime Max Temperature : 49
Recommended Min Temperature : 0
Recommended Max Temperature : 60
Temperature Min Limit : -41
Temperature Max Limit : 85
=== DRIVE HEALTH INDICATORS ===
ID | NAME | TYPE | UPDATE | RAW
VALUE | VALUE | THRESHOLD | WORST | STATUS | LAST
MODIFIED
1 Raw Read Error Rate Pre-fail online
0x0 200 51 200 100% OK 5/13/15
8:43 PM
3 Spin Up Time Pre-fail online
7,891 182 21 177 89.9% OK 11/29/15
2:25 PM
4 Start Stop Count Life-span online
4,129 96 0 96 96.0% OK 11/29/15
2:25 PM
5 Reallocated Sector Count Pre-fail online
0 200 140 200 100% OK -
7 Seek Error Rate Life-span online
0x0 200 0 200 100% OK -
9 Power On Hours Life-span online
5,078 94 0 94 94.0% OK 11/29/15
2:25 PM
10 Spin Retry Count Life-span online
0 100 0 100 100% OK -
11 Calibration Retry Count Life-span online
0 100 0 253 100% OK -
12 Power Cycle Count Life-span online
54 100 0 100 100% OK 11/28/15
4:19 PM
192 Power-Off Retract Count Life-span online
21 200 0 200 100% OK 11/12/15
2:02 PM
193 Load Cycle Count Life-span online
9,125 197 0 197 98.5% OK 11/29/15
2:25 PM
194 Temperature (Celsius) Life-span online
33 119 0 103 99.2% OK 11/29/15
2:25 PM
196 Reallocated Event Count Life-span online
0 200 0 200 100% OK -
197 Current Pending Sectors Count Life-span online
0 200 0 200 100% OK -
198 Offline Uncorrectable Sector Count Life-span offline
0 100 0 253 100% OK -
199 UDMA CRC Error Count Life-span online
0 200 0 200 100% OK -
200 Multi Zone Error Rate Life-span offline
0 100 0 253 100% OK -
=== DRIVE ERROR LOG ===
error log is empty
=== DRIVE SELF-TEST LOG ===
self-test log is empty
Regards,
John
> On Nov 29, 2015, at 1:42 PM, William Hermans <[email protected]> wrote:
>
> . . .the only purpose of a RAID backup is to prevent a single point of
> failure (like a disk failure) resulting in lost backups.
>
> You do not need a RAID array to prevent a single point of failure. You take
> those 3+ disks, put them in 3 different machines. Or even in the same machine
> as single drives. Same difference, only less wear and tear on the drives,
> more cost effective, and perhaps a small amount slower as singles.
>
> In the field you'll likely not run into any RAID 5/6 arrays. At least for
> corporate storage. You're more likely to see RAID10, or RAID0 + 1. Because
> there is nothing faster than striping disks, and RAID1 does not have an
> impact on performance if set up correctly. RAID5/6 is just a way for the home
> user to feel all warm and fuzzy . . and literally feed the companies who
> offer the hardware for such arrays. Be it controllers, or "special" hard
> drives . . . special software, chipsets with BS built in RAID( software ).
>
> I still use Seagate drives(nothing but), and have no issues. Why ? Probably
> because I do not run RAID. RAID is notorious for being hard on drives.
> Especially RAID 5/6. I will admit, that Seagate's reputation has gone into
> the toilette in the last 8 or so years. All their drives used to be lifetime
> warranty. Now days I think they give 3 years . . . not even as good as WD, or
> even Samsung SSDs . . .
>
> Anyway, seriously. Unless you're running a server that sees thousands+ of
> transactions a day. You don't need RAID. But hey, don't pay attention to me.
> . .
>
>
> On Sun, Nov 29, 2015 at 1:44 PM, John Syne <[email protected]
> <mailto:[email protected]>> wrote:
> That makes perfect sense. BTW, the only purpose of a RAID backup is to
> prevent a single point of failure (like a disk failure) resulting in lost
> backups.
>
> One thing to pay attention to is the MTBF numbers for disks. I was a firm
> believer in Seagate Barracuda disk until I had a whole number of them fail
> over a few months. Speaking Seagate tech support, they explained that the
> SMART data on these disks showed they had more than the 3,000 hours MTBF and
> hence I should have expected them to fail. I couldn’t believe what they told
> me; running their disks 24 hours/day, they expected failures in 1/3 of a
> year. They were right, look at the SMART data on Seagate disks and you will
> see read write errors in the 10’s of thousands or more.
>
> After that I use Western Digital RED disks which are designed for 24/7 NAS
> applications. Looking at the disk SMART data, I see 0 read/write errors.
>
> Regards,
> John
>
>
>
>
> > On Nov 29, 2015, at 3:37 AM, [email protected] <mailto:[email protected]> wrote:
> >
> > John Syne <[email protected] <mailto:[email protected]>> wrote:
> >> [-- text/plain, encoding quoted-printable, charset: UTF-8, 156 lines --]
> >>
> >> Yeah, but rsync only gives you a snapshot and not a history of your backup.
> >> When I really mess up, I want to go back to the state of my machine 15
> >> minutes ago, or two days ago. This has saved me a lot of head scratching,
> >> trying to find out where I messed up. I really like the way timemachine
> >
> > I use an rsync based incremental backup system (I wrote it myself
> > having used rsnapshot for a while, rsnapshot is OK but I think it's
> > too complex).
> >
> > I do hourly incremental backups locally to another disk on my main
> > machine and I do daily incremental backups to a remote machine. The
> > daily remote backups get thinned out as they get older so there are
> > daily backups for the last month, then monthly ones for 12 months,
> > then yearly ones.
> >
> > --
> > Chris Green
> > ·
> >
> > --
> > For more options, visit http://beagleboard.org/discuss
> > <http://beagleboard.org/discuss>
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