Using RAM instead of disk for build servers

Bjarne D Mathiesen macintosh at
Mon Mar 15 17:03:22 UTC 2021

Steven Smith wrote:
> SSD RAID offers speed and fault tolerance.
> Simple options that are tolerant to a single disk failure are:
>   * Free/one extra SSD: Use macOS Disk Utility to RAID 1 together two
>     smaller, inexpensive SSD drives for 100% redundancy.
>   * OWC ThunderBay 4 Mini, $279: Use macOS Disk Utility to RAID 1
>     together four smaller, inexpensive SSD drives for 100% redundancy
>     and larger capacity.
>   * OWC ThunderBay 4 Mini with SoftRAID, $379: Use SoftRAID to RAID
>     4 together four smaller, inexpensive SSD drives for 100% redundancy
>     and even larger capacity. (Caveats: no encryption, no boot volumes.)

OWC ThunderBay is a bad solution for the hardware specified unless one
is able to get

- OpenCore
- GigaByte Titan Ridge

to work

The xServe only has
- USB      480 MBit
- FireWire 800 MBit
which is far slower than the internal bays

I'm presently trying to get this to work on my MacPro 2010.

As to SoftRaid I simply can't recommend it.
I've bought a full license, and after trying it out, I've had to
un-install it again, as it made my whole system x10 slower when
accessing my existing disks.

1) is fundamentally incompatible with any usage of APFS
   I had 2 x 18 TB HDs in AppleRAID-1 with APFS and several sub-volumes
   After installing SoftRaid, the read/write speed was reduced by a
   factor 10
2) only supports HFS+
   according to my correspondance with OWC, they've no present plans for
   supporting APFS

Presently, I'm using OpenZFS on Mac on 4 x 6 TB HDs in RAIDZ-1
#=> cat createZFS

diskutil unmountdisk force disk4
diskutil unmountdisk force disk5
diskutil unmountdisk force disk6
diskutil unmountdisk force disk7

# set ashift to 13 when using SSD
zpool create \
    -f \
    -o ashift=12 \
    -O casesensitivity=sensitive \
    -O normalization=formD \
    -O compression=lz4 \
    BjarneZFS raidz1 \
    /dev/disk3 /dev/disk4 /dev/disk5 /dev/disk6
zpool set feature at encryption=enabled BjarneZFS

zfs create \
    -o encryption=on \
    -o keylocation=prompt \
    -o keyformat=passphrase \

zfs create BjarneZFS/BDMdata
zfs create BjarneZFS/Bjarne
zfs create BjarneZFS/EyeTV

zfs create BjarneZFS/HomeMesterD
zfs set quota=1G BjarneZFS/HomeMesterD

# this is for the Guest account
# you'll have to modify the Guest user using dscl
zfs create BjarneZFS/HomeGuest
zfs set quota=1G BjarneZFS/HomeGuest

zfs create \
    -o recordsize=16k \

OpenZFS has a better read cache than macOS :

I've got 2 x 4 TB HDs in the DVD-bays

/dev/disk2 & /dev/disk3 (internal, physical):
   #:                  TYPE NAME                SIZE     IDENTIFIER
   0: GUID_partition_scheme                  *4.0 TB     disk2
   1:                   EFI EFI               209.7 MB   disk2s1
   2:            Apple_APFS Container disk10  500.0 GB   disk2s2
   3:            Apple_RAID                   3.5 TB     disk2s3
   4:            Apple_Boot Boot OS X         134.2 MB   disk2s4
/dev/disk10 (synthesized):
   #:                 TYPE NAME                 SIZE     IDENTIFIER
   0:APFS Container Scheme -                 +500.0 GB   disk10
                            Physical Store disk2s2
   1:          APFS Volume Mojave 001          91.0 GB   disk10s1
   2:          APFS Volume Catalina 011 - Data 88.7 GB   disk10s2
   3:          APFS Volume Catalina 011        12.6 GB   disk10s3
   4:          APFS Volume Preboot             182.3 MB  disk10s4
   5:          APFS Volume Recovery            1.6 GB    disk10s5
   6:          APFS Volume VM                  1.1 MB    disk10s6
   7:          APFS Volume Big Sur - Data      86.0 GB   disk10s7
   8:          APFS Volume Big Sur             12.5 GB   disk10s8
/dev/disk7 (internal, virtual):
   #:                 TYPE NAME                 SIZE     IDENTIFIER
   0:           Apple_APFS                     +3.5 TB   disk7
/dev/disk11 (synthesized):
   #:                 TYPE NAME                 SIZE     IDENTIFIER
   0:APFS Container Scheme -                   +3.5 TB   disk11
                           Physical Store disk7
   1:          APFS Volume VMs                  2.1 TB   disk11s1
   2:          APFS Volume NyProg               148.8 GB disk11s2
   3:          APFS Volume Buffer               197.7 MB disk11s3

I haven't trid zvol + APFS, but I might try that at a later date
I've got 4 x original MiniStack, that at present has 2.5" 250 GB HDs
that I'll upgrade to 1 TB HDs. When I get these, I'll try to see what
happens with zvol + APFS

Bjarne D Mathiesen
Korsør ; Danmark ; Europa
denne besked er skrevet i et totalt M$-frit miljø
OpenCore + macOS 10.15.7 Cataina
MacPro 2010 ; 2 x 3,46 GHz 6-Core Intel Xeon ; 128 GB 1333 MHz DDR3 ECC
ATI Radeon RX 590 8 GB

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