We have bbb based custom board containing eMMC.
And we have created partitions as follows,
parted --script -a minimal /dev/mmcblk0 mklabel gpt mkpart primary 131072B 262143B mkpart primary 262144B 393215B mkpart primary 393216B 524287B mkpart primary 524288B 1572863B mkpart primary 1572864B 2621439B mkpart primary 2621440B 3145727B mkpart primary 3145728B 3276799B mkpart primary 3276800B 8519679B mkpart primary 8519680B 13762559B mkpart primary 13762560B 19005439B mkpart primary 19005440B 19267583B mkpart primary 19267584B 19529727B mkpart primary 19529728B 19791871B mkpart primary 20MiB 31MiB mkpart primary ext4 32MiB 232MiB mkpart primary ext4 232MiB 432MiB mkpart primary ext4 432MiB 532MiB mkpart primary ext4 532MiB 592MiB mkpart primary ext4 592MiB 792MiB mkpart primary ext4 792MiB 827MiB mkpart primary ext4 827MiB 3650MiB
With above command we are able to partition eMMC but alignment is set to minimal. We wanted to check how can we achieve optimal alignment ?
Is there any advantage in achieving optimal alignment ?
I referred this link but solutions like parted -a opt /dev/sdb mkpart primary 0% 100% can not be used as we need following structure.
# parted --list Model: MMC MMC04G (sd/mmc) Disk /dev/mmcblk0: 3842MB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 131kB 262kB 131kB 2 262kB 393kB 131kB 3 393kB 524kB 131kB 4 524kB 1573kB 1049kB 5 1573kB 2621kB 1049kB 6 2621kB 3146kB 524kB 7 3146kB 3277kB 131kB 8 3277kB 8520kB 5243kB 9 8520kB 13.8MB 5243kB 10 13.8MB 19.0MB 5243kB 11 19.0MB 19.3MB 262kB 12 19.3MB 19.5MB 262kB 13 19.5MB 19.8MB 262kB 14 21.0MB 32.5MB 11.5MB 15 33.6MB 243MB 210MB ext4 16 243MB 453MB 210MB ext4 17 453MB 558MB 105MB ext4 18 558MB 621MB 62.9MB ext4 19 621MB 830MB 210MB ext4 20 830MB 867MB 36.7MB ext4 21 867MB 3827MB 2960MB ext4
With current command if we replace minimal with optimal we are seeing following messages from parted,
Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance. Warning: The resulting partition is not properly aligned for best performance.
Any pointers/suggestions/correction for achieving optimal alignment ?
as suggested in the this link I extracted following values,
# cat /sys/class/mmc_host/mmc1/mmc1:0001/block/mmcblk0/queue/optimal_io_size 0 # cat /sys/class/mmc_host/mmc1/mmc1:0001/block/mmcblk0/queue/minimum_io_size 512 # cat /sys/class/mmc_host/mmc1/mmc1:0001/block/mmcblk0/alignment_offset 0 # cat /sys/class/mmc_host/mmc1/mmc1:0001/block/mmcblk0/queue/physical_block_siz e 512
mmc utils give following output,
# ./mmc extcsd read /dev/mmcblk0 ============================================= Extended CSD rev 1.5 (MMC 4.41) ============================================= Card Supported Command sets [S_CMD_SET: 0x01] HPI Features [HPI_FEATURE: 0x03]: implementation based on CMD12 Background operations support [BKOPS_SUPPORT: 0x01] Background operations status [BKOPS_STATUS: 0x02] 1st Initialisation Time after programmed sector [INI_TIMEOUT_AP: 0x7a] Power class for 52MHz, DDR at 3.6V [PWR_CL_DDR_52_360: 0x00] Power class for 52MHz, DDR at 1.95V [PWR_CL_DDR_52_195: 0x00] Minimum Performance for 8bit at 52MHz in DDR mode: [MIN_PERF_DDR_W_8_52: 0x00] [MIN_PERF_DDR_R_8_52: 0x00] TRIM Multiplier [TRIM_MULT: 0x06] Secure Feature support [SEC_FEATURE_SUPPORT: 0x15] Secure Erase Multiplier [SEC_ERASE_MULT: 0x02] Secure TRIM Multiplier [SEC_TRIM_MULT: 0x03] Boot Information [BOOT_INFO: 0x07] Device supports alternative boot method Device supports dual data rate during boot Device supports high speed timing during boot Boot partition size [BOOT_SIZE_MULTI: 0x10] Access size [ACC_SIZE: 0x06] High-capacity erase unit size [HC_ERASE_GRP_SIZE: 0x08] i.e. 4096 KiB High-capacity erase timeout [ERASE_TIMEOUT_MULT: 0x01] Reliable write sector count [REL_WR_SEC_C: 0x01] High-capacity W protect group size [HC_WP_GRP_SIZE: 0x01] i.e. 4096 KiB Sleep current (VCC) [S_C_VCC: 0x08] Sleep current (VCCQ) [S_C_VCCQ: 0x08] Sleep/awake timeout [S_A_TIMEOUT: 0x10] Sector Count [SEC_COUNT: 0x00728000] Device is block-addressed Minimum Write Performance for 8bit: [MIN_PERF_W_8_52: 0x08] [MIN_PERF_R_8_52: 0x08] [MIN_PERF_W_8_26_4_52: 0x08] [MIN_PERF_R_8_26_4_52: 0x08] Minimum Write Performance for 4bit: [MIN_PERF_W_4_26: 0x08] [MIN_PERF_R_4_26: 0x08] Power classes registers: [PWR_CL_26_360: 0x00] [PWR_CL_52_360: 0x00] [PWR_CL_26_195: 0x00] [PWR_CL_52_195: 0x00] Partition switching timing [PARTITION_SWITCH_TIME: 0x01] Out-of-interrupt busy timing [OUT_OF_INTERRUPT_TIME: 0x02] Card Type [CARD_TYPE: 0x07] HS Dual Data Rate eMMC @52MHz 1.8V or 3VI/O HS eMMC @52MHz - at rated device voltage(s) HS eMMC @26MHz - at rated device voltage(s) CSD structure version [CSD_STRUCTURE: 0x02] Command set [CMD_SET: 0x00] Command set revision [CMD_SET_REV: 0x00] Power class [POWER_CLASS: 0x00] High-speed interface timing [HS_TIMING: 0x01] Erased memory content [ERASED_MEM_CONT: 0x00] Boot configuration bytes [PARTITION_CONFIG: 0x00] Not boot enable No access to boot partition Boot config protection [BOOT_CONFIG_PROT: 0x00] Boot bus Conditions [BOOT_BUS_CONDITIONS: 0x00] High-density erase group definition [ERASE_GROUP_DEF: 0x01] Boot write protection status registers [BOOT_WP_STATUS]: 0x00 Boot Area Write protection [BOOT_WP]: 0x00 Power ro locking: possible Permanent ro locking: possible ro lock status: not locked User area write protection register [USER_WP]: 0x00 FW configuration [FW_CONFIG]: 0x00 RPMB Size [RPMB_SIZE_MULT]: 0x01 Write reliability setting register [WR_REL_SET]: 0x00 user area: existing data is at risk if a power failure occurs during a write operation partition 1: existing data is at risk if a power failure occurs during a write operation partition 2: existing data is at risk if a power failure occurs during a write operation partition 3: existing data is at risk if a power failure occurs during a write operation partition 4: existing data is at risk if a power failure occurs during a write operation Write reliability parameter register [WR_REL_PARAM]: 0x05 Device supports writing EXT_CSD_WR_REL_SET Device supports the enhanced def. of reliable write Enable background operations handshake [BKOPS_EN]: 0x00 H/W reset function [RST_N_FUNCTION]: 0x00 HPI management [HPI_MGMT]: 0x01 Partitioning Support [PARTITIONING_SUPPORT]: 0x03 Device support partitioning feature Device can have enhanced tech. Max Enhanced Area Size [MAX_ENH_SIZE_MULT]: 0x0001ca i.e. 1875968 KiB Partitions attribute [PARTITIONS_ATTRIBUTE]: 0x00 Partitioning Setting [PARTITION_SETTING_COMPLETED]: 0x00 Device partition setting NOT complete General Purpose Partition Size [GP_SIZE_MULT_4]: 0x000000 [GP_SIZE_MULT_3]: 0x000000 [GP_SIZE_MULT_2]: 0x000000 [GP_SIZE_MULT_1]: 0x000000 Enhanced User Data Area Size [ENH_SIZE_MULT]: 0x000000 i.e. 0 KiB Enhanced User Data Start Address [ENH_START_ADDR]: 0x000000 i.e. 0 bytes offset Bad Block Management mode [SEC_BAD_BLK_MGMNT]: 0x00
EDIT: Achieved optimal alignment as suggested by “Глеб Майоров”, Except first 3 partition(which I can’t change) other small partitions are changed to minimum of 1MiB size. And except for 3 partitions, all other partitions seems to be aligned. Here is the latest partitioning script I used for eMMC.(Please note: In below script I have changed partition sizes w.r.t above script)
parted --script -a optimal /dev/mmcblk0 mklabel gpt mkpart primary 128KiB 255KiB mkpart primary 256KiB 383KiB mkpart primary 384KiB 511KiB mkpart primary 1MiB 2MiB mkpart primary 2MiB 3MiB mkpart primary 3MiB 4MiB mkpart primary 4MiB 5MiB mkpart primary 5MiB 10MiB mkpart primary 10MiB 15MiB mkpart primary 15MiB 20MiB mkpart primary 20MiB 21MiB mkpart primary 21MiB 22MiB mkpart primary 22MiB 23MiB mkpart primary 23MiB 30MiB mkpart primary ext4 30MiB 530MiB mkpart primary ext4 530MiB 1030MiB mkpart primary ext4 1030MiB 1130MiB mkpart primary ext4 1130MiB 1190MiB mkpart primary ext4 1190MiB 1720MiB mkpart primary ext4 1720MiB 1755MiB mkpart primary ext4 1755MiB 100%
Answers:
Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.
Method 1
Try to align to eMMC erasure block size. It usually equals 0.5, 1, 2, 4, 8 MiB depending on eMMC datasheet. If you find block size alignment too much memory wasting, then stick to the page size, generally found in the range of 4..16 KiB.
Try to make partition sizes and borders a multiple of erasure block size, so when file system writes to the first or last FS block, memory card doesn’t have to erase and rewrite beginning/end of next/previous partition.
Don’t rely on parted‘s features to align, just take a calculator, pen and a sheet of paper, and count up a correct borders in sectors or bytes.
Personally, I prefer aligning to 8 MiB border, because it isn’t waste too much memory, and any partition starts and ends on erasure block border regardless of specific erasure block size, so I don’t need to search for memory card documentation.
Optimal alignment reduces write amplification factor, so your memory could last longer.
Method 2
The answer depends on the disk. parted displayed the error message
not aligned: 2048s % 65535s != 0s
when I tried to partition a Kingston SA400M8120G. However,a Samsung 980 PRO 250GB could be partitioned arbitrarily without warnings. A hint comes from the dmesg log when plugging in the Kingston drive (via a USB → NVMe adapter):
[81602.009178] scsi 6:0:0:0: Direct-Access ASMT 2115 0 PQ: 0 ANSI: 6 [81602.010206] sd 6:0:0:0: Attached scsi generic sg1 type 0 [81602.021292] sd 6:0:0:0: [sda] 234441648 512-byte logical blocks: (120 GB/112 GiB) [81602.021390] sd 6:0:0:0: [sda] Write Protect is off [81602.021395] sd 6:0:0:0: [sda] Mode Sense: 43 00 00 00 [81602.021619] sd 6:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [81602.021903] sd 6:0:0:0: [sda] Optimal transfer size 33553920 bytes [81602.061285] sd 6:0:0:0: [sda] Attached SCSI disk
The most important information is the Optimal transfer size 33553920 bytes. I.e., for “optimal alignment” the partitions shall begin at integer multiples of 33553920 (= 65535 ⋅ 512) bytes.
Based on How to align partitions for best performance using parted I resolved the alignment problem by querying the sys filesystem. The disk to partition was /dev/sda, the system is a current (2020-12-22) Archlinux, kernel 5.9.14-arch1-1, parted is revision 3.3:
DISK="sda"
OPTIMAL_IO_SIZE=$(cat /sys/block/${DISK}/queue/optimal_io_size)
ALIGNMENT_OFFSET=$(cat /sys/block/${DISK}/alignment_offset)
PHYSICAL_BLOCK_SIZE=$(cat /sys/block/${DISK}/queue/physical_block_size)
With these variables I could calculate the start sectors of the partitions. Knowing the values of OPTIMAL_IO_SIZE and PHYSICAL_BLOCK_SIZE I adjusted the magic numbers to 11 and 128:
START_EFI=$(((OPTIMAL_IO_SIZE+ALIGNMENT_OFFSET)/PHYSICAL_BLOCK_SIZE)) START_SWAP=$((START_EFI+11*OPTIMAL_IO_SIZE/PHYSICAL_BLOCK_SIZE)) START_ROOT=$((START_SWAP+128*OPTIMAL_IO_SIZE/PHYSICAL_BLOCK_SIZE))
With this knowledge, invoking parted is straightforward:
parted -s -a optimal /dev/${DISK} mklabel gpt
mkpart "Efi" fat32 ${START_EFI}s $((START_SWAP-1))s
mkpart "Swap" linux-swap ${START_SWAP}s $((START_ROOT-1))s
mkpart "root" ext4 ${START_ROOT}s 100%
set 1 esp on
print
Verify that the alignment is correct:
parted /dev/sda align-check optimal 1 align-check optimal 2 align-check optimal 3
The output reads:
1 aligned 2 aligned 3 aligned
As already stated, the answer above is for a “Kingston SA400M8120G”. I must admit, I have not found any other device (SATA drive, SDCard, NVMe drive, USB stick) which reports an “Optimal transfer size” different from 0. From that I would conclude that the latter drives do not require a special alignment. And parted does not report alignment warnings for them.
All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0